Poster B90, Sunday, March 26, 8:00 – 10:00 am, Pacific Concourse
The neural correlates of functional compensation in high performing older adults
Abdelhalim Elshiekh1, Sricharana Rajagopal2, Stamatoula Pasvanis2, Elizabeth Ankudowich1, Natasha M Rajah1,2; 1Department of Neuroscience, McGill University, 2Douglas Mental Health University Institute and Department of Psychiatry, McGill University
Despite the common belief that cognitive decline is inevitable in older adulthood, recent evidence suggest that some older adults perform similarly to younger adults (YA) in a variety of cognitive tasks, including episodic memory tasks. Prior fMRI studies revealed that these “high”-performing older adults (HOA) exhibit increased PFC activity compared to lower-performing older adults (LOA), which may reflect functional compensation in the aging brain. However, this assumes that these groups only differ in brain activation patterns and performance, when in fact they may represent distinct subsamples in the population. In this fMRI study, we compared performance-related brain activity in YA, LOA and HOA during successful encoding and retrieval of spatial context memory tasks. The goal was to determine the patterns of functional compensation in HOA vs LOA compared to YA. We tested 24 LOA, and 20 HOA who were split based on performance on a separate temporal context memory task, and 45YA. Multivariate behaviour partial least square analysis (B-PLS) was used to identify patterns of whole-brain activity that correlate with performance across groups. Behaviourally, independent samples t-tests show that YA performed better than LOA but not HOA, while HOA scored higher than LOA. The B-PLS analysis indicated that compared to LOA, activity in medial PFC and ventral visual areas in HOA was predictive of successful encoding and retrieval. Interestingly, activity in those same areas was predictive of successful encoding and retrieval in HOA vs YA despite the comparable performance in both groups. Theoretical implications of these findings will be discussed.
Topic Area: LONG-TERM MEMORY: Development & aging