Marshall GA, Olson LE, Frey MT, Maye J, Rentz DM, Sperling RA, Johnson KA.
Instrumental activities of daily living impairment is associated with increased amyloid burden.
Human Amyloid Imaging 2011 Meeting Abstracts. 2011 Jan 15;
Background: Impairment in instrumental activities of daily living (IADL) greatly increases caregiver burden and
is a hallmark of Alzheimer's disease (AD). IADL impairment in AD has been associated with frontal and posterior
hypometabolism in vivo and with global amyloid deposition in post-mortem studies. With the advent of Pittsburgh
Compound B (PIB) PET imaging, it is now possible to visualize amyloid deposition in vivo much earlier in the
Objective: We sought to determine whether IADL impairment is associated with increased cortical PIB retention
in normal older control (NC) and mild cognitive impairment (MCI) subjects.
Methods: Fifty-six subjects (19 NC and 37 MCI) participating in ADNI or an investigator-initiated ADNI ancillary
study underwent clinical assessments and dynamic PIB PET imaging. Cortical PIB retention was evaluated using
the distribution volume ratio (DVR, cerebellar reference). Global PIB retention and then precuneus and superior
and middle frontal PIB retention were correlated with IADL using the Functional Activities Questionnaire (FAQ).
Linear multiple regression analyses were conducted with FAQ as the dependent variable and PIB retention, age,
education, AMNART IQ, and memory performance as predictors.
Results: Mean age was 74.6}7.2 years, 63% male, education 16.6}2.8 years, AMNART IQ 120.8}10.4, RAVLT
delayed recall 5.5}4.5, MMSE 28.4}1.6, and FAQ 2.4}3.7. In the linear regression model including all subjects,
greater IADL impairment was associated with greater global (R2 = 0.30, p = 0.003 for model; partial s = 4.9, p = 0.002),
precuneus (R2 = 0.33, p = 0.001 for model; partial s = 4.6, p = 0.001), and middle and superior frontal PIB retention
(R2 = 0.28, p = 0.004 for model; partial s = 3.9, p = 0.004). When looking at MCI subjects only, these associations
Conclusions: These results suggest that daily functional impairment is related to greater amyloid burden within
the spectrum of MCI. Future longitudinal studies will help determine whether early amyloid deposition will predict
rapid functional decline and progression to dementia.