Poster B96, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
Older adults with one vs. no apolipoprotein E type 4 allele display different patterns of fMRI activity related to recognition, but not to spatial context
E. H. Yu1,2, M-E Lafaille-Magnan1,2, S. Pasvanis2, S. Rajagopal2, M.N. Rajah1,2, PREVENT-AD Research Group3; 1McGill University, 2Douglas Mental Health University Institute, Montreal, Quebec, Canada, 3https://preventad.loris.ca/team_2016_09_16.pdf
Episodic memory decline is characteristic of Alzheimer’s disease. The apolipoprotein E type 4 allele (APOE4) increases risk for such dementia. We used fMRI technique to examine the relation of APOE4 status to brain responses in object recognition & spatial-context recall in healthy elderly with a family history of Alzheimer’s. Some 25 APOE4-positive (mean age = 62 years) and 44 APOE4-negative (mean age = 64 years) older adults were recruited by the PREVENT-AD program (Montreal, Canada). Participants were instructed to memorize 48 coloured objects in their spatial context (left/right) during encoding. Following a 20-minute delay, participants were asked to recognize these old objects and to recall their spatial context among 48 new objects during retrieval. No group difference was found on test accuracy or reaction time. Multivariate Partial Least Square (PLS) analysis assessed group similarities and differences with this task on brain responses during encoding and retrieval. We observed a group*phase interaction for objects recognized without correct spatial context. Specifically, APOE4-positive adults activated the left medial temporal, inferior parietal, superior-middle temporal, posterior cingulate and fusiform cortices to a greater degree at encoding than at retrieval, whereas APOE4-negative adults activated these regions more at retrieval than at encoding. We conclude that APOE4 status affects recognition-related brain responses in older adults at high risk for Alzheimer’s, even though such an effect is not apparent on behavioural levels.
Topic Area: LONG-TERM MEMORY: Episodic