Instrumental activities of daily living impairment is associated with increased amyloid burden

BACKGROUND/AIMS: Instrumental activities of daily living (IADL) impairment in Alzheimer's disease has been associated with global amyloid deposition in postmortem studies. We sought to determine whether IADL impairment is associated with increased cortical Pittsburgh Compound B (PiB) retention.
METHODS: Fifty-five subjects (19 normal older controls, NC, and 36 with mild cognitive impairment, MCI) underwent clinical assessments and dynamic PiB positron emission tomography imaging.
RESULTS: A linear multiple regression model showed that greater IADL impairment was associated with greater global PiB retention in all subjects (R(2) = 0.40; unstandardized partial regression coefficient, β = 5.8; p = 0.0002) and in MCI subjects only (R(2) = 0.28; β = 6.1; p = 0.003), but not in NC subjects only.
CONCLUSION: These results suggest that daily functional impairment is related to greater amyloid burden in MCI.