Relationship Between Brain Amyloid Deposition and Instrumental Activities of Daily Living in Older Adults : a Longitudinal Study from the Multidomain Alzheimer Prevention Trial

Objectives: To examine the evolution of instrumental activity of daily living (IADL) performance according to the presence of brain amyloid deposition. Design: Longitudinal analysis of a randomized controlled trial. Setting: Neuroimaging ancillary study from the Multidomain Alzheimer Prevention Trial (MAPT). Participants: Community-dwelling individuals aged 70 and older without dementia (N = 269; 60% female, mean age 75±4). Measurements: Linear mixed models were used to assess the 36-month evolution of the performance of an IADL questionnaire for primary prevention studies in dementia, the Activity of Daily Living Prevention Instrument (ADL-PI), according to the presence of amyloid deposition using florbetapir positron emission tomography (PET) (standardized uptake value≥1.17). Additional analyses were also conducted to examine the changes in specific domains of daily functioning with and without adjustment for age, sex, apolipoprotein E, randomization group, and time between baseline and PET examination. Results: One hundred two (37.9%) participants were amyloid positive. Amyloid-negative participants had statistically significant improvement in ADL-PI total score between baseline and 36 months (p=.04). The difference after 3 years between amyloid-positive and -negative participants was not significant (β=–0.95±0.53 at 36 months, p=.08; adjusted models: β=–1.07±0.56, p=.06). Amyloid-negative participants also improved in memory-related IADLs (p<.001) throughout the study, unlike amyloid-positive participants. Conclusion: Amyloid-positive and -negative older adults are likely to have different trajectories in IADL performance. Future research is needed to better understand the relationship between amyloid plaques and functional limitations.