|Dr. Larry Seidman|
Studies of schizophrenia and related disorders:
The laboratory in clinical neuroscience and developmental neuropsychology is focused primarily on questions involving the developmental neuropsychological, neuroanatomical and brain functional precursors of subsequent psychotic disorder, and their links to genetic factors. Thus, understanding the etiology and pathophysiology of the psychoses, especially as measured by neuropsychological and magnetic resonance imaging (MRI) measures in schizophrenia, is a fundamental direction for this lab, particularly in relationship to neurodevelopment in adolescence. Because psychotic illnesses arise largely during adolescence and young adulthood (ages 18-30), the study of normal brain development during this period is also a focus of the laboratory.
In 1983, Dr. Seidman proposed one of the first neuropsychological "network" hypotheses of schizophrenia, suggesting that dysfunction in an attentional network involving the frontal lobe, limbic system, and deep sub-cortical regions including the thalamus and brain stem, was core to schizophrenia (Seidman, in the Psychological Bulletin, 1983). This hypothesis was subsequently applied to the vulnerability for schizophrenia (i.e., hypothesizing that abnormalities in this network would be present before the psychotic illness appeared). Over the past 2 decades, in collaboration with colleagues, post-docs and graduate students, Dr. Seidman has conducted structural MRI and functional MRI (fMRI) studies of attention, executive function (cognitive control), working and declarative memory, and the default network, in persons with different forms of psychosis (schizophrenia, bipolar disorder) and their family members. He later applied related strategies to the study of ADHD, another neurodevelopmental disorder involving a disorder of executive control.
Research subjects at different stages of psychotic illness (e.g., first-episode, chronic) are assessed, as are those with varying degrees of genetic or clinical risk for developing the illness. The latter include "clinical-high-risk' populations who exhibit "prodromal" (attenuated) symptoms of psychotic illness, such as unusual beliefs or suspiciousness, and social and functional problems, and "genetic high-risk' populations who are the non-psychotic first-degree relatives of persons with psychosis, who themselves are at elevated risk to develop a psychotic illness and also exhibit milder forms of cognitive deficits seen in psychotic illnesses. The long-term goal of this research program is the identification of stable, reliable and/or heritable biomarkers of illness ("endophenotypes") for use in both genetic studies and in early identification, treatment, cognitive remediation and prevention efforts.
Drs. Tsuang and Faraone, close collaborators of Dr. Seidman for more than 20 years, initiated the search for endophenotypes in our research group; these are genetically transmitted markers of illness that are putatively closer to the genes than clinical phenotypes. The study of abnormal psychobiological traits in first-degree relatives is largely unconfounded by medications or active psychosis. In this approach, it is assumed subtle cognitive or physiological abnormalities in relatives represent markers that are presumably more proximal to disease-risk genes than are clinical symptoms or psychiatric diagnosis (which represent complex interactions of genes with environmental factors and are limited by current diagnostic methods in psychiatry). Another major goal of this research is to characterize neurobiological events occurring just prior to and during psychosis onset, and to understand whether normal developmental changes during adolescence and early adulthood play a role in this process. An overarching hypothesis is that acute illness may arise from a combination of genetic and developmental factors at different phases, including the perinatal period and later events of adolescence, and that alterations in the normal development of prefrontal-hippocampal circuitry is central to the risk for schizophrenia.
The neuroimaging studies conducted in the laboratory employ a combination of imaging modalities, including structural MRI, functional MRI (fMRI), diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy (1H-MRS). The majority of data was collected on 1.5T scanners at the Athinoula A. Martinos Center, beginning in 1993 and were analyzed using Statistical Parametric Mapping (SPM) software and custom routines in MATLAB. However all current studies of the "prodromal" period for psychosis are being studied at 3T and will be analyzed using a combination of SPM8, FreeSurfer and FSFAST.
Click on the link below to learn more about the studies.
I. Studies of Persons with Psychosis and their First-Degree Relatives.
A. The Neuropsychological Family Study of Adult Relatives
B. The Adolescent High-Risk Study
C. The Birth Cohort Study
II. Studies of the Clinical High Risk "Prodromal" Period for Psychosis
A. The CIDAR Study
B. The NAPLS Project
III. Other Studies of Psychosis
A. Glucose enhancement of memory in schizophrenia: a Functional MRI study to determine neuroanatomical sites of action
IV. Other Studies of Neurodevelopment - ADHD
V. Other Studies of Aging
IV. Other Studies of Neurodevelopment - Attention Deficit/Hyperactivity Disorder (ADHD)
I. Studies of Persons with Psychosis and their First-Degree Relatives.
These studies had a number of phases: These included, 1). Clinical characterization of families including their psychotic and non-psychotic adult relatives (> age 17), 2). Neuroimaging of these participants, 3). Clinical characterization of non-psychotic relatives < age 30, 4). Neuroimaging of these participants, 5). Applying similar methods to a longitudinal birth cohort follow-up study in collaboration with Drs. Stephen Buka, Jill Goldstein and Ming Tsuang. These will be selectively described briefly below focusing on imaging studies.
A. The Neuropsychological Family Study of Adult Relatives
1986-1988 US Department of Veterans Affairs: "Neuropsychological Functioning and Genetic Risk Prediction in Schizophrenia" (Stephen Faraone, Ph.D., PI)
1987-1991 NIMH RO1 41874: "Drug Response and Genetic Factors in Schizophrenia" (Ming Tsuang, M.D., Ph.D., PI)
1988-1998 NIMH R18 43518: "Schizophrenia: Psychopathology and Heterogeneity" (Ming Tsuang, M.D., Ph.D., PI)
1994-1997 Theodore and Vada Stanley Foundation Award: "Functional MRI and Auditory Sustained Attention in First-Degree Relatives of Schizophrenic Patients" (Larry J. Seidman, Ph.D., PI)
We found that first-degree, non-psychotic relatives of persons with schizophrenia manifest a significant increase in negative symptoms, neuropsychological abnormalities (especially attention, executive and verbal memory difficulties), and structural and functional brain abnormalities compared to normal controls. We used fMRI to study performance of an auditory working memory version of the Continuous Performance Test (CPT) that requires interference resolution in non-psychotic relatives of persons with schizophrenia and comparable controls (matched on age, sex, ethnicity, handedness, parental education and reading ability). Subjects were recruited as part of a larger neuropsychological study of 430 persons recruited from the Boston metropolitan area. We hypothesized that non-psychotic first-degree relatives would exhibit alterations in different regions of the attention and interference control network, including the prefrontal and parietal cortices, thalamus, hippocampus and anterior cingulate. Compared to controls, relatives showed greater task-elicited activation in the PFC, and the anterior and dorsomedial thalamus (Thermenos et al., 2004). Findings in the dorsomedial thalamus were replicated in an independent sample using the same methods(Seidman et al., 2007). When fMRI signal change was modeled as a function of increasing working memory load, there was a significant group-by-load interaction, with relatives showing significantly greater task-elicited activation in the right dorsomedial thalamus compared to controls. Greater dorsomedial thalamic activation in the relatives remained significant when controlling for group differences in working memory performance, Vocabulary score and education. Results of this study suggest that altered dorsomedial thalamic activation is a feature of neurobiological risk for schizophrenia, independent of the psychotic state (Seidman et al., 2007).
In structural MRI studies, we tested a number of hypotheses (Seidman et al., 2002): 1). Hippocampal volume is smaller in non-psychotic relatives than in controls, particularly in the left hemisphere. 2). Hippocampi will be smaller in multiplex, as compared to simplex relatives, and both will be smaller than in controls. 3). Hippocampal volumes and verbal declarative memory function will be positively correlated. 4). Hippocampi will be smaller in persons with schizophrenia than in their non-psychotic relatives, or than controls. Subjects were 45 non-psychotic adult first-degree relatives, from families with either two ("multiplex", n=17) or one ("simplex", n=28) person diagnosed with schizophrenia, 18 relatives with schizophrenia, and 48 normal controls. Sixty contiguous 3-millimeter coronal, T1-weighted 3D magnetic resonance images of the brain were acquired on a 1.5 Tesla magnet at Massachusetts General Hospital. Volumes of total cerebrum and the hippocampus were measured. Compared to controls, relatives, particularly from multiplex families, had significantly smaller left hippocampi. Verbal memory and left hippocampal volumes were significantly and positively correlated. Within families, hippocampal volumes did not differ between schizophrenia patients and their non-psychotic relatives. Results support the hypothesis that the vulnerability to schizophrenia includes smaller left hippocampi and verbal memory deficits. Findings suggest that smaller left hippocampi and verbal memory deficits are an expression of early neurodevelopmental compromise reflecting the degree of genetic liability to schizophrenia.
Utilizing the same dataset (Seidman et al., 2003), because verbal declarative memory (VDM) deficits are prominent, and the parahippocampal gyrus is considered to be centrally involved with the hippocampus in verbal declarative memory processing, we analyzed parahippocampal data from a family study of schizophrenia. Results provide some support for the hypothesis that the vulnerability to schizophrenia includes abnormal volumes of the parahippocampal gyrus. These data, while less robust than seen in studies of the hippocampus, provide further support for the hypothesis that some medial temporal lobe abnormalities in schizophrenia are associated with genetic risk for the disease and are independent of psychosis.
B. The Adolescent High-Risk Study ("Adolescent Development Study")
2002-2005 Mental Illness and Neuroscience Discovery (MIND) Institute Grant: "Towards the primary prevention of schizophrenia: Neurobiological studies of families with schizophrenia" (Larry J. Seidman, Ph.D., PI)
2003-2007 NIMH R18 MH 43518: "Schizophrenia: Psychopathology and Heterogeneity" (Larry J. Seidman Ph.D., PI).
2005-2008 NARSAD Independent Investigator Award: "Specificity of Pre-illness Vulnerability in Bipolar disorder versus Schizophrenia" (Larry J. Seidman Ph.D., PI).
2009-2011 NIMH R21 MH083205 "Language and Risk in Schizophrenia" (Delisi, PI), (Matcheri Keshavan, MD and Larry J. Seidman, Ph.D., Co-PIs)
Compared to the studies of adults described earlier, there is far less research evaluating these parameters in adolescent and young adult high risk subjects. Further, at the time this study began, there were no studies to date of brain activation during verbal memory in relatives (a robust neurocognitive deficit seen in schizophrenia), and no studies comparing young persons at genetic risk for schizophrenia to those at genetic risk for bipolar disorder.
We hypothesized that non-psychotic relatives of persons with schizophrenia are at higher risk for abnormalities in prefrontal-hippocampal circuitry compared to normal controls, manifest as smaller hippocampal volumes, reduced attention, verbal declarative memory, working memory and executive functions, as well as altered activity in the dorsolateral prefrontal cortex (DLPFC) during working memory and altered hippocampal activity during verbal encoding.
Working memory:Compared to controls, those at genetic risk for schizophrenia had significantly greater Phobic Anxiety, and marginally greater Psychoticism than controls on the Symptom Checklist-90-Revised, and showed significantly greater task-elicited activation in the right DLPFC (BA 46). Psychopathology, IQ, and in-scanner WM performance did not account for group differences. Data support a physiological difference in DLPFC in adolescents at genetic risk for schizophrenia, independent of psychosis (Seidman et al., 2006).
New analyses are ongoing to test the effects of risk for affective psychosis in relation to working memory. While preliminary, findings by Thermenos et al. suggest exaggerated activity in structures involved in emotion and reward processing, which, if replicated, may represent biomarkers of genetic risk for BD. Direct comparisons of those at-risk for the two psychotic disorders are planned.
Verbal Encoding:Using the same sample as used in the Working Memory experiment, compared to controls, those at genetic risk for schizophrenia had more psychopathology, reduced performance on a context memory test, and greater repetition suppression of activation in the left and right anterior parahippocampus (in entorhinal cortex region) during word-pair encoding, after controlling for possible confounders. This was the first study to demonstrate an alteration of brain activity in the parahippocampal gyrus in persons at genetic risk for schizophrenia (Thermenos et al., 2007).
Default Network (Whitfield-Gabrieli et al., 2009): We examined the status of the neural network mediating the default mode of brain function, which typically exhibits greater activation during rest than during task, in patients with early schizophrenia and young first-degree relatives of persons with schizophrenia. As expected, controls exhibited task-related suppression of activation in the default network including medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), lateral parietal cortex, and hippocampus, while patients and relatives exhibited reduced task-related suppression in all those regions, except in the PCC for the relatives. Task-related suppression in the MPFC correlated positively with working memory performance and negatively with psychopathology ratings in all three groups. Patients and relatives exhibited abnormally high functional connectivity between default network regions during rest, with the degree of connectivity correlating with psychopathalogy in the patients. Hyperactivation (reduced task-related suppression) of default regions and hyperconnectivity of the default network may contribute to disturbances of thought in schizophrenia and the risk for the illness. In contrast to the pattern seen in genetic-risk for schizophrenia, we predicted that genetic risk for bipolar disorder would be associated with greater abnormalities in emotion-regulation and reward circuitry (ventral PFC/ orbitofrontal gyrus, anterior insula and cingulate, basal ganglia and amygdala). Future studies can assess whether brain abnormalities observed in relatives can significantly contribute to psychosis-conversion prediction algorithms.
New Study: The "Language and Risk" neuroimaging study (DeLisi, PI) will be conducted at MIT and a number of Harvard Medical School affiliated sites. The neuroimaging portion of the study aims to determine 1) whether there are structural and functional changes in the brain white matter frontotemporal pathways (uncinate, arcuate, inferior longitudinal, inferior occipito-frontal fasciculi) in first-degree relatives of persons with schizophrenia, who are at genetic high risk for developing the disease, and 2) if white matter changes can predict which persons at high-risk will eventually develop symptoms of schizophrenia. We hypothesize that one of the neurodevelopmental bases for schizophrenia is a disturbance in the white matter pathways involved in processing language and related functions, and that these changes will be detectable by MRI in significantly more well individuals that are at genetic risk for developing the illness than in those who are not. To test these hypotheses, 60 genetic high-risk subjects and 30 age, sex, and social class proportionally matched controls (N=30) will be evaluated with DTI and fMRI using a lexical decision task previously shown to differentiate people with schizophrenia and people at high-risk for schizophrenia from controls. Deficits observed will identify high-risk individuals that may have a high risk for schizophrenia and thus be valuable for decisions about early intervention.
C. The Birth Cohort (New England Family) Study of Persons with Schizophrenia, Affective Psychoses and their First-Degree Relatives
1997-2003 Theodore and Vada Stanley Foundation Award: "A Functional and Structural MRI study of Brain Abnormalities in Schizophrenic Persons and Their Siblings: Impact of Obstetric and Genetic Factors" (Larry J. Seidman, Ph.D., PI)
1998-2002 NARSAD (National Association for Research in Schizophrenia and Depression) Experienced Investigator Award: "Are Medial Limbic and Prefrontal Brain Abnormalities Unique to Schizophrenia? A Functional and Structural MRI Study Using a Bipolar Sib-pair Design" (Larry J. Seidman, Ph.D., PI)
2002-2008 NIMH R01 MH 63951: "Family Study of Psychosis: Brain, Genes, & Prenatal Risk" (Larry J. Seidman, Ph.D., PI)
In a large-scale, prospective, multi-site study of pregnant women receiving prenatal care and their offspring, we followed-up a subgroup of participants enrolled in the Providence and Boston cohorts of the National Collaborative Perinatal Project (NCPP; a two-generation community cohort which enrolled pregnant women and their offspring born between 1959-1966, followed from pregnancy through age seven) who had developed Schizophrenia or Bipolar disorder ("probands"). Probands, their non-psychotic siblings and healthy controls were studied using structural MRI, diffusion tensor imaging (DTI) and functional MRI during performance of the same sequential letter, "N-back" working memory task and a word pair encoding task which examined the effect of novelty used in the "Adolescent High-Risk" study. In addition, blood was collected for future studies of susceptibility genes for schizophrenia, and a pilot study of markers of neuronal function was collected using proton magnetic resonance spectroscopy in a smaller sub-group of first-degree relatives of persons with schizophrenia and in controls. This study provides a rare opportunity to 1) examine the impact of both Pre-and-Perinatal Complications (PPCs) and genetic factors on brain abnormalities in two major psychotic disorders, 2) test hypotheses about the specificity of brain abnormalities in the two disorders, and 3) potentially identify unique and common endophenotypic traits in first-degree relatives of persons with a major psychotic disorder.
Based on our previous work, we hypothesized that 1) DLPFC, the parietal lobe, thalamus, amygdala-hippocampal region and parahippocampal gyrus are altered in first degree relatives of schizophrenia patients compared to controls, 2) structural and functional brain abnormalities are related to neuropsychological deficits and a higher-incidence of PPCs in patients and relatives, and 3) both psychotic groups will exhibit abnormalities in the medial prefrontal cortex, while bipolar subjects and their first degree relatives will exhibit unique abnormalities in emotion-processing and reward networks (ventral PFC, orbitofrontal cortex, amygdala, insula, anterior cingulate, basal ganglia and subregions of the cerebellum).
Thermenos et al., (2005) investigated the effect of working memory performance on brain activation in persons with schizophrenia and controls. Persons with schizophrenia showed significantly greater activation than controls in the right medial frontal gyrus and left inferior parietal lobule/medial temporal gyrus region (BA 39/40), and a trend toward greater activation in the left ventrolateral PFC after statistical adjustment for performance differences. Data are consistent with findings of studies showing increased PFC and parietal activation in schizophrenia when the effects of reduced WM task performance in patients with schizophrenia are addressed.
Thermenos et al., (2009), showed that persons with bipolar disorder and their first-degree relatives failed to suppress activation in the left anterior insula (BA 13) during working memory, whereas controls suppressed activation. Compared to controls, relatives also failed to suppress activation in the orbitofrontal cortex (OFC) and superior parietal cortex. Controls and relatives exhibited greater activation than BD individuals in the left frontopolar cortex (BA10) during WM. Results remained significant after controlling for confounders except for mild attenuation of OFC findings. Significant correlations between brain activity, mood and working memory suggested that activity in working memory circuits was affected by activity in emotion-regulatory circuits. We concluded that persons with bipolar disorder and their relatives exhibit altered activity in the frontopolar cortex and insula, which may represent biomarkers of genetic risk for BD. Analyses of data directly comparing persons with schizophrenia vs. bipolar disorder and their first-degree relatives are ongoing (Milanovic et al).
II. Studies of the Clinical High Risk "Prodromal" Period for Psychosis
The prodromal phase leading to psychosis is a pre-psychotic stage when the earliest attenuated symptoms of psychosis appear (i.e., unusual beliefs or suspiciousness, and signs of social withdrawal and/or functional deterioration). It is believed this period may be a critical window of opportunity for preventative intervention, as preliminary studies in prodromal and first-episode schizophrenia subjects suggest that cognitive and brain changes occur early, during the prodromal phase, and could be the future targets of drug or psychosocial preventative interventions. Second generation antipsychotic medications, for example, which have fewer neurological side effects than the previous drugs may be "neuroprotective" and may, if administered early, prevent or delay the onset of or attenuate illness symptoms and prevent or lessen cognitive decline. The general goal of this research program is to identify 1) predictors and mechanisms of conversion to psychosis (including development of a psychosis risk prediction algorithm), and 2) targets for early intervention and preventative treatment.
A. The CIDAR (Centers for Intervention Development and Applied Research) Study:
2007-2012 P50 MH080272 (CIDAR); "Vulnerability to Progression Schizophrenia" (Robert McCarley, MD, PI): "Project 1: Functional Anatomy of Neurocognitive Deterioration in Schizophrenia" (Project PI, MGH sub-contract: Larry J. Seidman, Ph.D.)
The purpose of this study is to further characterize the pre-psychotic, symptomatic phase of psychotic disorders ("prodrome") using MRI. The overaching hypothesis of this MRI study is that schizophrenia is characterized by a decline in neuropsychological and brain function, much of it occurring before the first episode in the prodromal period prior to onset of psychosis and to the formal diagnosis of schizophrenia. We will map brain structural changes as well as the functional neuroanatomy of neurocognitive decline during the prodromal period (PRO-SZ) at baseline and at one-year follow-up. We hypothesize that deterioration in executive functions during the prodromal period is associated with increasing cortical and cortical-limbic abnormalities in gray and white matter. To evaluate these hypotheses, we will assess 75 PRO-SZ and 60 comparable healthy controls (HC), who will be assessed twice: at baseline and one-year follow-up. We expect 1) abnormal brain volumes and functioning of the hippocampus, parahippocampal gyrus (PHG), insula, orbital frontal cortex (OFC), anterior cingulate cortex (ACC), and superior temporal gyrus (STG); 2) a decrease in overall cortical (especially DLPFC and STG) and paralimbic (PHG, ACC, OFC) gray matter volumes, an increase in lateral ventricular size, and reduced DLPFC and PHG activity from baseline assessment over time. These changes will be associated with other variables collected at other study sites, including familial genetic loading, clinical symptoms, conversion to first-episode schizophrenia, gamma oscillations/other ERP measures, levels of stress, trauma, and cortisol, and genetic variation in specific candidate genes.
B. The NAPLS (North American Prodrome Longitudinal Studies) Project:
2008-2013 NIMH 1 U01 MH081928-01A1; "3/8- Predictors and Mechanisms of Conversion to Psychosis" (PI, Harvard/Beth Israel Deaconess Medical Center [BIDMC] and MGH subcontract: Larry J. Seidman Ph.D.). This is one of 8 sites in this "U01" study. Others are at Emory, UCLA, UCSD, UNC, University of Calgary, Yale, and Zucker Hillside Hospital (New York)
This is a prospective, longitudinal study of 90 prodromal patients and 30 healthy controls at the BIDMC/Harvard site (ages 13-30 of any sex, race or ethnicity, as part of a multisite study of 720 prodromal patients and 240 matched healthy controls across all 8 NAPLS sites). Participants will be assessed clinically every six months over a two-year follow-up period, and tested on laboratory procedures at baseline, 12- and 24-months. For participants who develop frank psychosis or a psychotic disorder, a clinical assessment will be conducted at that time (assuming clinical stability). Procedures will include commonly used and standardized clinical, psychosocial, and neurocognitive assessment protocols, and neuroimaging, electrophysiological, hormonal and genomics assessments that will enable elucidation of predictive biomarkers and changes associated with onset of psychotic illness. Based on the previously collected NAPLS phase I data (that was merged into an NIMH-initiated federated database in 2005), a conversion to psychosis (e.g., a threshold level of psychosis that typically meets diagnostic criteria for a psychiatric disorder like schizophrenia) rate of just over 30% is expected with follow-up. This will generate the largest prodromal sample and highest number of "converted" subjects within the field and will provide statistical power and scientific scope that cannot be duplicated by any single study. Once subjects are clinically rated as "converted" to psychosis, regardless of where they are in the two-year study, they will be assessed one more time (assuming clinical stability), and their participation in this study will end (i.e., study participants are followed for two years or to "conversion" to psychosis, whichever comes first). The aims of the study are: 1) to replicate and further develop a clinical psychosis risk prediction algorithm, (which includes genetic risk recent deterioration in functioning, higher levels of unusual thought content, higher levels of suspicion-paranoia, and greater social impairment at baseline; 2) to determine whether neuroanatomical, neurophysiological, neurocognitive, and neurohormonal abnormalities that precede psychosis represent stable vulnerability markers or markers of progression during the prodromal phase; 3) to determine whether prefrontal and medial temporal lobe (MTL) volume, P300 and mismatch negativity amplitudes, markers of memory and executive function and cortisol secretion predict conversion; 4) to determine whether biological markers independently predict conversion, or if they significantly enhance the predictive power and sensitivity of the clinical prediction algorithm, and 5) to develop a repository of DNA and RNA from subjects meeting diagnostic criteria for a clinical high risk state and from demographically similar healthy subjects for future genetic association studies.
III. Other Studies of Psychosis:
A. 2000-2002 NARSAD Young Investigator Award: "Glucose enhancement of memory in schizophrenia: a Functional MRI study to determine neuroanatomical sites of action" (William Stone, Ph.D., PI).
Verbal declarative memory is one of the most reliably impaired cognitive functions in schizophrenia. Important issues are whether the problem is reversible, and which brain regions underlie improvement. We showed previously that glucose administration improved declarative memory in patients with schizophrenia, and sought in this pilot study to identify whether glucose affects the location or degree of activation of brain regions involved in a verbal encoding task. Seven clinically stable and medicated patients with schizophrenia or schizoaffective disorder, who showed deficits on a clinical test of memory, participated in the study. Subjects served as their own controls in a double-blind, crossover protocol that consisted of two sessions about a week apart. In each session, subjects ingested a beverage flavored with lemonade that contained 50 grams of glucose on one occasion, and saccharin on the other. Blood glucose was measured before and 15, 50 and 75 minutes after ingestion. After ingesting the beverage, they performed a verbal encoding task while undergoing brain fMRI. The results showed significantly greater activation of the left parahippocampus during novel sentence encoding in the glucose condition, compared to the saccharin condition, despite no change in memory performance. A trend towards greater activation of the left DLPFC (p < 0.07) was also evident in the glucose condition. These pilot findings emphasize the sensitivity of both the medial temporal and prefrontal regions to effects of glucose administration during encoding, and are consistent with the hypothesis that these regions also participate in declarative memory improvements following glucose administration.
B. 2008-2009 Glaxo Smith-Kline GT1-111777 "Neural Correlates of Cognitive Change in Response to the Brain Fitness Program in Schizophrenia." (Matcheri Keshavan, MD, Co-PI, Larry J. Seidman, Ph.D., Co-PI)
This study aims to understand the effects of adding supervised training on a Brain Fitness Programô (BFP, Posit Science Corp, San Francisco, CA), a game-like computer program, to existing antipsychotic medication in patients with deteriorated schizophrenia to determine if there are any quantifiable changes in cognition, independent functioning, brain structure and function. In this prospective study, patients with chronic schizophrenia who are stabilized on atypical antipsychotics will be recruited and undergo baseline neuropsychological, psychological and functional assessments at the BIDMC. Once enrolled in the BIDMC study, a portion of those subjects will be recruited for a neuroimaging study. Subjects will undergo baseline cognitive, functional, neuroimaging assessments, followed by a 21-week supervised training on the BFP. Post-treatment, all assessments will be repeated. The neuroimaging protocol includes structural and DTI scans, as well as fMRI during performance of 2 tasks: a sequential letter 'N-back' working memory task (described above), and a verbal subsequent memory task which probes source memory for context (thought to be dependent on the PFC) and structures in the medial temporal lobe. In the memory test, subjects first undergo a learning phase during scanning. In this phase, subjects memorize words while prompted to perform deep vs. shallow encoding (i.e., shallow: ("Is this object bigger or smaller than a shoebox?"; deep: "Is this a living or not-living object?") After scanning, subjects complete a self-paced recognition memory test comprising all of the previously studied words and additional foil words. Subjects are tested on 1) how well they remember both the words (is the word 'old' or 'new') and the source information (which of the two questions, animacy or size, was associated with a word). Further, if they answer 'old', they are prompted to determine whether they "Remember" specific information about the word or whether the word is "Familiar" (they cannot recall any specific information about the word). We predict that improved post-BFP working memory will be associated with changes in PFC and posterior parietal cortex activity, while improved memory will be associated with changes in PFC and MTL activity.
2002-2008 NIMH RO1 MH/HD 62152: The Neuroanatomy of Adult ADHD: An MRI Morphometric Study” (Larry J. Seidman, Ph.D., PI).
2002-2005 March of Dimes Foundation (MOD): “Brain Function and Structure in Adults with
Dyslexia and Attention Deficit/Hyperactivity Disorder: Relationship to Obstetric Factors” (Larry J. Seidman, Ph.D., PI).
The specific aims of this project, defining the neuroanatomical basis of ADHD, have been supported primarily by two grants funded from 2002-2008 (see below). The goals of these studies are to examine brain structure and functioning in children and adults with and without ADHD using neuropsychological tests, functional magnetic resonance imaging (fMRI) and structural MRI. We: 1) examined the neuroanatomic bases of ADHD in children and adults; 2) measured the relationship of brain structure, function, and neuropsychological dysfunctions in ADHD; 3) studied the heterogeneity of brain abnormalities in ADHD; 4) evaluated the effects of gender and age on brain abnormalities in ADHD; 5) created a resource for brain-gene studies of adult ADHD; and 6) will relate measures of brain function, structure and neuropsychological function to obstetric factors.
In the first (NIMH funded) study, a total of 285 subjects have been brain imaged under this and other related protocols (see below) and after a number of subjects were excluded for bad scans, a final sample of 279 was formed. This includes 96 controls, 151 persons with ADHD (36 with comorbid bipolar disorder), 18 persons with bipolar disorder, 10 relatives of persons with ADHD, and 4 persons with ADHD NOS due to later age of onset. 79 participants were between ages 10-19 (31 controls) and 43 persons with ADHD, and 200 were twenty years of age or older. Thirty-three persons with ADHD were psychotropically naïve at the time of brain imaging. These include participants imaged in collaboration with Dr. Valera when she carried out her NRSA post-doctoral fellowship (Dr. Seidman, mentor: F32 MH065040: “A Functional MRI Study of Working Memory in ADHD Adults), in collaboration with Dr. Biederman, who was supported by NARSAD, and the rest collected solely under this grant. All 279 subjects brains have had comprehensive morphometric analyses carried out at the MGH Center for Morphometric Analysis including general segmentation and cortical parcellation and an additional 137 had specialized cerebellar parcellation analyses. Although not originally part of the grant aims, a pilot study of 76 participants received diffusion tensor imaging (DTI) scans including 56 controls and 17 persons with ADHD. In addition, functional MRI data was collected on 235 of the 279 participants 12 and older using the n-back (2-back task) and multi-source interference (MSIT) task. In addition to support from this grant, patients and controls were sampled from the "Testing the Validity of Adult Attention Deficit Hyperactivity Disorder" (Faraone, MH 57934-05) study, the “A Genetic Linkage Study of Children with Attention Deficit Hyperactivity Disorder” (Faraone, HD 37694) study, the “Adult Outcome of Attention Deficit Hyperactivity Disorder” (Biederman, HD 36317-07) study, the “Long Term Outcome of ADHD in Girls” (Biederman, MH 50657-08) study, the NARSAD Distinguished Investigator Award to Dr. Beiderman (“Neuropsychology and Neuroimaging Study of Mania”), the “Open Label Phase I/II Study of the Safety and Dopamine Transporter Binding Properties of C-11 Altropane in Normal Human Subjects and in Patients with ADHD” (Spencer, MH 064019), and the “Open-Label Phase I/II Study of Dopamine Transporter Receptor Occupancy with OROS Methylphenidate and Immediate Release Methylphenidate as Measured with C-11 Altropane in Human Subjects” (Spencer, 2003-P-002058). Dr. Faraone’s, Dr. Biederman’s, and Dr. Spencer’s studies include structured psychiatric interviews, diagnostic procedures, neuropsychological tests, and blood draws for genetic analyses. All were IRB approved at MGH Participants were also recruited from the community and received the same clinical measures as subjects from Dr. Faraone’s, Dr. Biederman’s, Dr. Spencer’s studies.
Aim 1. Identifying the neuroanatomic bases of ADHD in children and adults:
To this date, we have completed a number of publications examining this aim. These studies are summarized below:
Many investigators have hypothesized that attention-deficit/hyperactivity disorder (ADHD) involves structural and functional brain abnormalities in frontal–striatal circuitry. Although our review suggests that there is substantial support for this hypothesis, a growing literature demonstrates widespread abnormalities affecting other cortical regions and the cerebellum. Because there is only one report studying adults with ADHD, this summary is based on children. A key limitation of the literature is that most of the studies until recently have been underpowered, using samples of fewer than 20 subjects per group. Nevertheless, these studies are largely consistent with the most comprehensive and definitive study (Castellanos et al 2002). Moreover, studies differ in the degree to which they address the influence of medications, comorbidities, or gender, and most have not addressed potentially important sources of heterogeneity such as family history of ADHD, subtype, or perinatal complications. Despite these limitations, a relatively consistent picture has emerged. The most replicated alterations in ADHD in childhood include significantly smaller volumes in the dorsolateral prefrontal cortex (DLPFC), caudate, pallidum, corpus callosum, and cerebellum. These results suggest that the brain is altered in a more widespread manner than has been previously hypothesized. Developmental studies are needed to address the evolution of this brain disorder into adulthood (Seidman et al., 2005).
Convergent data from neuroimaging, neuropsychological, genetic, and neurochemical studies in ADHD have implicated dysfunction of DLPFC and dorsal anterior cingulate (dACC) cortical structures, which form the cortical arm of the frontostriatal network supporting executive functions. Furthermore, besides the DLPFC and dACC, structural and functional imaging studies have shown abnormalities in key brain regions within distributed cortical networks supporting attention. The conceptualization of neural systems biology in ADHD aims at the understanding of what organizing principles have been altered during development within the brain of a person with ADHD. Characterizing these neural systems using neuroimaging could be critical for the description of structural endophenotypes and may provide the capability of in vivo categorization and correlation with behavior and genes (Makris et al., 2009).
Although there are many structural neuroimaging studies of ADHD in children, there are inconsistencies across studies and no consensus regarding which brain regions show the most robust area or volumetric reductions relative to control subjects. Our goal was to statistically analyze structural imaging data via a meta-analysis to help resolve these issues. We searched the MEDLINE and PsycINFO databases through January 2005. Studies must have been written in English, used MRI, and presented the means and standard deviations of regions assessed. Data were extracted by one of the authors and verified independently by another author. Analyses were performed using STATA with metan, metabias, and metainf programs. A meta-analysis including all regions across all studies indicated global reductions for ADHD subjects compared with control subjects, standardized mean difference =.408, p < .001. Regions most frequently assessed and showing the largest differences included cerebellar regions, the splenium of the corpus callosum, total and right cerebral volume, and right caudate. Several frontal regions assessed in only two studies also showed large significant differences. This meta-analysis provides a quantitative analysis of neuroanatomical abnormalities in ADHD and information that can be used to guide future studies (Valera et al., 2007).
Gray and white matter volume deficits have been reported in a number of studies of children with ADHD; however, there is a paucity of structural MRI studies of adults with ADHD. This structural MRI study used an a priori region of interest approach. Twenty-four adults with DSM-IV ADHD and 18 healthy controls comparable on age, socioeconomic status, sex, handedness, education, IQ, and achievement test performance had an MRI on a 1.5T Siemens scanner. Cortical and sub-cortical gray and white matter were segmented. Image parcellation divided the neocortex into 48 gyral-based units per hemisphere. Based on a priori hypotheses we focused on prefrontal, anterior cingulate cortex (ACC) and overall gray matter volumes. General linear analyses of the volumes of brain regions, adjusting for age, sex, and total cerebral volumes, were used to compare groups. Relative to controls, ADHD adults had significantly smaller overall cortical gray matter, prefrontal and ACC volumes. Adults with ADHD have volume differences in brain regions in areas involved in attention and executive control. These data, largely consistent with studies of children, support the idea that adults with ADHD have a valid disorder with persistent biological features (Seidman at al., 2006).
ADHD has been associated with structural alterations in brain networks influencing cognitive and motor behavior. Volumetric studies in children identify abnormalities in cortical, striatal, callosal, and cerebellar regions. In a prior volumetric study we found that ADHD adults had significantly smaller overall cortical gray matter, prefrontal and anterior cingulate volumes than matched controls. Thickness and surface area are additional indicators of integrity of cytoarchitecture in the cortex. To expand upon our earlier results and further refine the regions of structural abnormality, we carried out a structural MRI study of cortical thickness in the same sample of adults with ADHD (n = 24) and controls (n = 18), hypothesizing that the cortical networks underlying attention and executive function (EF) would be most affected. Compared to healthy adults, adults with ADHD showed selective thinning of cerebral cortex in the networks that subserve attention and EF. In the present study we found significant cortical thinning in ADHD in a distinct cortical network supporting attention especially in the right hemisphere involving the inferior parietal lobule, the dorsolateral prefrontal and the anterior cingulate cortex. This is the first documentation that ADHD in adults is associated with thinner cortex in the cortical network that modulates attention (Makris et al., 2007).
ADHD has been hypothesized to be due, in part, to structural defects in brain networks influencing cognitive, affective and motor behaviors. Although the current literature on fiber tracts is very limited in ADHD, gray matter abnormalities suggest that white matter connections may be altered selectively in neural systems. A prior study (Ashtari and others, 2005), using DT-MRI showed alterations to be present within the frontal and cerebellar white matter in children and adolescents with ADHD. In this study of DT-MRI in adults with childhood ADHD (funded by the March of Dimes Foundation), we hypothesized that the fiber pathways subserving attention and executive functions would be altered. To this end, the cingulum bundle and the superior longitudinal fascicle II (SLF II) were investigated in vivo in 12 adults with childhood onset ADHD and 17 demographically comparable unaffected controls using DT-MRI. Relative to the controls, the fractional anisotropy (FA) values were significantly smaller in both regions of interest in the right hemisphere, indicating an alteration of anatomical connections within the attention and executive function cerebral systems in adults with childhood ADHD. The demonstration of FA abnormalities in the cingulum bundle and SLF II in adults with childhood ADHD provides further support for persistent structural abnormalities into adulthood (Makris et al., 2008).
Although ADHD and bipolar disorder (BPD) frequently co-occur and represent a particularly morbid clinical form of both disorders, neuroimaging research addressing this comorbidity is scarce. Our aim was to evaluate the morphometric MRI underpinnings of the comorbidity of ADHD with BPD testing the hypothesis that subjects with this comorbidity would have neuroanatomical correlates of both disorders. Morphometric MRI findings were compared between 31 adults with ADHD and BPD with those of 18 with BPD, 26 with ADHD, and 23 healthy controls. The volumes (cm3) of our regions of interest were estimated as a function of ADHD status, BPD status, age, sex, and omnibus brain volume using linear regression models. When BPD was associated with a significantly smaller orbital prefrontal cortex and larger right thalamus, this pattern was found in comorbid subjects with ADHD plus BPD. Likewise, when ADHD was associated with significantly less neocortical gray matter, less overall frontal lobe and superior prefrontal cortex volumes, a smaller right anterior cingulate cortex, and less cerebellar gray matter, so did comorbid ADHD plus BPD subjects. Results support the hypothesis that ADHD and BPD independently contribute to volumetric alterations of selective and distinct brain structures. In the comorbid state of ADHD plus BPD, the profile of brain volumetric abnormalities consists of structures that are altered in both disorders individually. Attention to comorbidity is necessary to help clarify the heterogeneous neuroanatomy of both BPD and ADHD (Biederman et al., 2008).
Summary of Results of analyses: Volumetric and surface area (i.e., thickness) measures indicate that adults with ADHD have structural brain abnormalities (reductions) in overall gray matter, DLPFC, cerebellum, anterior cingulate cortex and the inferior parietal lobule, consistent with a network that regulates attention and executive control. The abnormalities are largely bilateral, but greater involvement of the right hemisphere is suggested by abnormalities in white matter, thus far measured in the cingulum bundle and right superior longitudinal fascicle (SLF) II. In contrast to results reported in the literature on children with ADHD, no significant differences were noted in the basal ganglia (i.e., caudate, pallidum and putamen), consistent, in part, with the Castellanos finding of “normalization” of caudate volume by late teenage years. Areas that we had proposed to be abnormal in ADHD based on theoretical reasons, such as thalamus and nucleus accumbens, were not significantly different than controls. While the abnormalities are not accounted for by comorbidity, some findings are observed in patients with ADHD+BP, such as volume reductions in orbital PFC. Thus, careful attention to the nature of comorbidity is necessary to understand neuroanatomical deviations in persons with ADHD+ comorbid disorders. We have yet to test for differences in corpus callosum, and also to directly test child and adult samples to determine if the results are comparable using the same methods. These results strongly support the validity of adult ADHD from the point of view of the presence of anatomical abnormalities in networks subserving attention and executive control.
Aim 2. Relating brain structure, function and neuropsychological dysfunctions:
We hypothesized that ADHD symptoms can be accounted for by structural and functional abnormalities in fronto-subcortical networks. Our specific hypotheses involve response inhibition and working memory. We predict that response inhibition deficits will be associated with a smaller anterior cingulate, caudate and pallidum, and altered blood flow in the ACC and DLPFC. We also predict that working memory deficits will be associated with smaller DLPFC and with reduced blood flow in DLPFC, ACC and parietal cortex.
The objective of this first analysis was to identify the neural correlates of ADHD adults during performance on a verbal working memory task. A sample of un-medicated adults with ADHD (N=20) and controls (N=20) group matched on age, sex, and estimated IQ was assessed. A 2-back task of working memory was used to examine neural function, and the blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) response was used as a measure of neural activity during working memory performance. Working memory performance on the 2-back task did not differ significantly between ADHD adults and controls. However, compared to controls, ADHD adults showed significantly decreased activity in cerebellar and occipital regions, and a trend toward decreased activation in an a priori region of the prefrontal cortex (p < .07). In conclusion, ADHD adults showed altered patterns of neural activity despite comparable task performance. These findings suggest that the cerebellum is involved in the pathophysiology of at least some cognitive deficits associated with ADHD, and emphasize the need for additional research aimed at elucidating the role of the cerebellum in ADHD symptomatology (Valera et al., 2005).
Although ADHD in adults is associated with significant morbidity and dysfunction and afflicts both sexes, relatively few imaging studies have examined females and none have had sufficient power to adequately examine sex differences. We sought to examine sex differences in neural functioning of ADHD adults during performance on a verbal working memory task. Participants were 44 adults with ADHD matched on age, sex, and estimated IQ to 49 controls. Accuracy and reaction time on an n-back task were measures of working memory performance. The blood-oxygenation-level dependent functional magnetic resonance imaging response was used as a measure of neural activity. A group by sex ANOVA showed no between-group differences in either reaction time or percent correct for the working memory task. For imaging data, with both sexes combined, ADHD adults showed less activity than controls in prefrontal regions. However, sex-by-group analyses revealed an interaction, such that male ADHD adults showed significantly less activity lateralized to right frontal, temporal and subcortical regions, as well as left occipital and cerebellar regions relative to male controls, whereas female ADHD adults showed no differences from female controls. Exploratory correlation analyses revealed negative associations between working memory related activation and number of hyperactive symptoms for males and number of inattentive symptoms for females. Male but not female adults with ADHD showed significantly altered patterns of neural activity during performance on a verbal working memory task. Males and females showed different associations between neural activity and ADHD symptoms (Valera et al., in Press).
Previous studies have reported hypofunction and structural abnormalities of the dorsal anterior midcingulate cortex (daMCC) in ADHD. Stimulant medications are effective treatments for ADHD, but their mechanism-of-action has not been established. We hypothesized that, compared to placebo, the extended-action osmotic-release oral system of methylphenidate (MPH-OROS, Concerta®) would increase functional MRI activation in daMCC and other fronto-parietal regions that subserve attention during the Multi-Source Interference Task (MSIT). Twenty-one adults with ADHD were randomized to six weeks of treatment with either MPH-OROS (n = 11) or placebo (n = 10). Subjects underwent fMRI twice while performing the MSIT (Baseline Scan 1, t = 0, and Scan 2, t = 6 weeks). Random effects, repeated measures, general linear model (GLM) analyses were used to compare daMCC (and whole-brain) fMRI activation during the MSIT via standard group-averaged methods. Additional individual-based daMCC volume-of-interest (VOI) confirmatory analyses and behavioral data are also presented. Performance (reaction times and accuracy) and baseline fMRI measures in daMCC and other a priori brain regions did not differ between groups. At treatment completion, a stringent random effects comparison of daMCC activation during the MSIT showed ADHD subjects on MPH-OROS had significantly higher daMCC fMRI activation than did those given placebo (P < .05, corrected for multiple comparisons). Activity in daMCC was related to clinical response at six weeks, with MPH-responders showing higher daMCC activation than placebo failures (P < .01). Individual-based daMCC VOI analyses confirmed the group-averaged findings. MPH-OROS increased activation of daMCC during the MSIT, and thus may act, in part, by normalizing hypofunction of daMCC and fronto-parietal regions in ADHD (Bush et al., 2008).
Although ADHD is associated both with brain alterations in attention and EF circuitry and with genetic variations within the dopamine system (including the dopamine transporter gene [SLC6A3]), few studies have directly investigated how genetic variations are linked to brain alterations. We sought to examine how a polymorphism in the 3’ untranslated region (UTR) of SLC6A3, associated with ADHD in meta-analysis, might contribute to variation in dorsal anterior cingulate cortex (dACC) function in subjects with ADHD. We collected fMRI scans of 42 individuals with ADHD, all of European descent and over the age of 17, while they performed the Multi-Source Interference Task (MSIT), a cognitive task shown to activate dACC. SLC6A3 3’ UTR variable number tandem repeat (VNTR) polymorphisms were genotyped and brain activity was compared for groups based on allele status. ADHD individuals homozygous for the 10R allele showed significant hypoactivation in the left dACC compared to 9R-carriers. Exploratory analysis also showed trends toward hypoactivation in the 10R homozygotes in left cerebellar vermis and right lateral prefrontal cortex. Further breakdown of genotype groups showed similar activation in individuals heterozygous and homozygous for the 9R allele. Alterations in activation of attention and EF networks found previously to be involved in ADHD are likely influenced by SLC6A3 genotype. This genotype may contribute to heterogeneity of brain alterations found within ADHD samples (Brown et al., In Press).
Summary of Results for Aim 2: Our results thus far strongly support the presence of dysfunction in DLPFC, dACC, and the cerebellum in ADHD, again supporting the validity of adult ADHD from a biological point of view. In general, despite normal performance that is statistically indistinguishable from controls on both the 2-back and MSIT, there is clear evidence of hypofunction of these regions in persons unmedicated at the time of scanning, especially in males with ADHD. To some extent, this disturbance can be ameliorated in dACC by classic ADHD medications such as Concerta. Of interest is that the dACC hypoactivation is at least partly influenced in the 10R homozygotes of the dopamine transporter gene [SLC6A3]. To this date, analyses have not supported the hypothesis of striatal involvement, consistent with the absence of structural alterations in the striatum in our adult subjects. Ongoing analyses are designed to test structure-function associations.
Aim 3. Assessing the heterogeneity of brain abnormalities in ADHD:
Because a familial subgroup (with at least one first degree relative with ADHD) may index a more biologically robust entity, we predicted that adults with a family history of ADHD will have a higher frequency of individuals with structural abnormalities in the ACC, caudate and pallidum, and with functional abnormalities in the ACC and DLPFC, than those without a family history. Considering that neuroanatomical abnormalities have been associated with both ADHD and LD, we hypothesize that persons with ADHD+LD will demonstrate structural brain abnormalities associated with both disorders. We also predict that a subgroup of persons with ADHD will be identified as impaired on executive functions, and that they will have more evidence of structural and functional brain abnormalities in prefrontal cortex, caudate, pallidum and ACC.
To this date, our focus on heterogeneity has addressed a few important issues involving the presence or absence of learning disabilities on neuropsychological performance (Seidman et al., 2006), the effect of dopamine D4 receptor on PFC volumes (Monuteaux et al., 2008), and the role of medications on ACC volumes (Makris et al., In Press).
The authors’ goal was to assess neuropsychological performance in girls with ADHD and evaluate the role of comorbid learning disabilities (LDs). Participants were 140 girls with ADHD and 122 girls without ADHD, ages 6–17 years. Neuropsychological performance was measured in a standardized manner, blind to clinical status. LD was defined by a combined regression-based and low-achievement classification. ADHD was associated with modest, but significant, neuropsychological impairment, as measured by an aggregate measure of performance and on the Stroop Color–Word Test, independent of age, social class, IQ, and psychiatric comorbidity. Neuropsychological deficits were most impaired in girls with both ADHD and an LD and in those without medications. These results extend to females the previously documented association of LDs with neuropsychological functioning in males with ADHD.
An emerging literature has demonstrated an association between the dopamine D4 receptor (DRD4) gene and volumetric brain abnormalities in children with ADHD. However, these results have not been extended to adults and have not addressed the impact of comorbidity. Our objective was to examine the DRD4 7R gene and volumetric brain abnormalities in adults with ADHD while accounting for comorbidity with bipolar disorder. Subjects were male and female adult outpatient referrals stratified into two diagnostic groups: 24 with ADHD, 19 with ADHD and bipolar disorder (BPD), as well as 20 male and female adult community controls without ADHD or BPD. We measured volumes (cm3) of a priori selected brain regions (superior frontal, middle frontal, anterior cingulate, and cerebellum cortices) by structural MRI. Among adults with ADHD, subjects with the 7-repeat allele of the DRD4 gene had a significantly smaller mean volume in the superior frontal cortex and cerebellum cortex compared to subjects without this allele. In contrast, no such effects were detected in the adults with ADHD+BPD or controls. Our findings suggest that volumetric abnormalities in the DLPFC and cerebellum may represent an intermediate neuroanatomical phenotype between DRD4 genotype and the clinical expression of ADHD in adults, but only in ADHD subjects without comorbid BPD. These result support the heterogeneity of ADHD and provides insights as to its underlying pathophysiology.
We sought to examine preliminary results of brain alterations in anterior cingulate cortex (ACC) in treatment-naïve adults with ADHD. The ACC is a central brain node for the integration of cognitive control and allocation of attention, affect and drive. Thus its anatomical alteration may give rise to impulsivity, hyperactivity and inattention, which are cardinal behavioral manifestations of ADHD. Segmentation and parcellation of the ACC was performed on controls (n=22) and treatment-naïve adults with ADHD (n=13). There was a 21% volume reduction in the left ACC of the treatment-naïve group. These results raise the possibility that in ADHD there are volumetric deficits persistent into adulthood, that are independent of medical treatment.
Summary of Results for Aim 3: Our results suggest that structural brain alterations in ADHD may be selectively found in persons with specific genotypes such as those mediated by the DRD4 7R gene. The role of medication was explored in a pilot study, and neuropsychological data was reported to demonstrate the important of comorbid LD. Ongoing analyses are designed to test heterogeneity of brain abnormalities.
Aim 4. Exploring the effects of gender on brain abnormalities in ADHD:
Because there is no structural brain imaging data available for adult ADHD, virtually nothing is known about whether the predicted effects will be similar for males and females with the disorder. We will determine whether results found in preliminary structural MRI studies of girls and functional imaging studies of women will be replicated: more left lateralized abnormalities in females than males with ADHD.
ADHD is known to have neuropsychological correlates, characterized mainly by
executive function deficits. However, most available data are based on studies of boys through age 12. Our goal was to assess whether girls with ADHD express neuropsychological features similar to those found in boys, and whether these impairments are found in both pre-teen and teen samples. Subjects were 101 girls and 103 boys with DSM-III-R ADHD, and 109 comparison girls and 70 boys without ADHD, ages 9 to 17 years. Information on neuropsychological performance was obtained in a standardized manner blind to clinical status. Primary regression analyses controlled for age, SES, learning disability and psychiatric co-morbidity. Girls and boys with ADHD were significantly more impaired on some measures of executive functions than healthy comparisons, but did not differ significantly from each other. With the exception of one test score there were no significant sex by diagnosis interactions. Moreover, there were no more significant interactions between age, gender and diagnosis than would be expected by chance. Neuropsychological measures of executive functions were comparably impaired in girls compared to boys with ADHD, and these impairments are found at ages 9-12 and ages 13-17. These findings suggest that executive dysfunctions are correlates of ADHD regardless of gender and age, at least through the late teen years (Seidman et al., 2005, Valera et al., In Press).
Summary of Results for Aim 4: Our results suggest that structural brain alterations in the PFC in ADHD may be selectively found in persons with specific genotypes such as those mediated by the DRD4 7R gene. The role of medication was explored in a pilot study, and neuropsychological data was reported to demonstrate the important role of comorbid LD. Ongoing analyses are designed to test heterogeneity of brain abnormalities.
Aim 5. Creating a resource for future studies of brain abnormalities in ADHD including associations with genetic anomalies:
The proposed work will provide a resource for future studies of brain abnormalities in ADHD. This resource will consist of the clinical data and DNA samples being collected. Although it would be premature to propose a study of the association between gene variants and brain abnormalities in ADHD, we believe that when ADHD susceptibility genes have been discovered and confirmed, our DNA-imaging resource will provide a useful means of testing hypotheses about gene-brain associations.
One hundred twenty four people with ADHD and 68 controls have brain imaging data as well as genetic data collected under a number of protocols in Dr. Biederman’s lab. We have carried out two pilot studies of imaging genetics with these datasets.
As noted above, we measured volumes (cm3) of a priori selected brain regions (superior frontal, middle frontal, anterior cingulate, and cerebellum cortices) by structural MRI. Among adults with ADHD, subjects with the 7-repeat allele of the DRD4 gene had a significantly smaller mean volume in the superior frontal cortex and cerebellum cortex compared to subjects without this allele. In contrast, no such effects were detected in the adults with ADHD+BPD or controls. Our findings suggest that volumetric abnormalities in the DLPFC and cerebellum may represent an intermediate neuroanatomical phenotype between DRD4 genotype and the clinical expression of ADHD in adults, but only in ADHD subjects without comorbid BPD (Monuteaux et al., 2008).
As noted above, ADHD individuals homozygous for the 10R allele showed significant hypoactivation in the left dACC compared to 9R-carriers. Exploratory analysis also showed trends toward hypoactivation in the 10R homozygotes in left cerebellar vermis and right lateral prefrontal cortex. Further breakdown of genotype groups showed similar activation in individuals heterozygous and homozygous for the 9R allele. Alterations in activation of attention and EF networks found previously to be involved in ADHD are likely influenced by SLC6A3 genotype (Brown et al., In Press).
Summary of Results for Aim 5: Our results suggest that structural and functional brain alterations in ADHD may be selectively found in persons with specific genotypes such as those mediated by the DRD4 7R and the DAT1 SLC6A3 genotype. These data are quite promising and novel. As noted below in “D” (Plans), we intend to seek additional funding to analyze these data in full.
V. Studies of Aging:
A. 2003-2008 NIA RO1 AG 022381 (Kremen, PI, UCSD), "The VETSA Longitudinal MRI Twin Study of Aging" (PI, Harvard/MGH site sub-contract: Larry J. Seidman, Ph.D.)
Neuroanatomical data was collected from 600 men at midlife to create a normative library of high-resolution MRIs and to identify genetic and environmental determinants of individual differences in neuroanatomy during midlife using the classical twin method. Analyses of regional gray, white, and ventricular volumes, cortical thickness, CBV and T2*-weighted maps of hippocampal formation, WMH volumes, and DTI, as well as their relationship other variables (cognitive functioning, alcohol, drug, and cigarette consumption, medical illness, cardiovascular risk factors, dietary habits, and physical activity) are underway. We predict that the some brain structures may be more influenced by genetic factors and others more by environmental factors. Additional funding has been obtained for follow-up MRIs for 5 additional years, yoked to subsequent waves of cognitive, personality and health data collection in the larger VETSA study. We will prospectively examine differential rates of regional brain change, and determine the extent to which genetic and environmental factors contribute to both stability and change over time. We will also use the MRI data for risk identification by examining associations of regional brain changes with cognitive and health/medical measures over time.
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