Poster B23, Sunday, March 25, 8:00-10:00 am, Exhibit Hall C
Functional segregation loss over time is moderated by APOE genotype in healthy elderly
Eric Kwun Kei Ng1, Yingwei Qiu1,2, June C Lo1, Evelyn SC Koay3,4, Woon-Puay Koh1,5, Michael WL Chee1, Juan Zhou1,6; 1Duke-NUS Medical School Singapore, 2Third Affiliated Hospital of Guangzhou Medical University, China, 3Yong Loo Lin School of Medicine, National University of Singapore, 4National University Hospital Singapore, 5Saw Swee Hock School of Public Health, National University of Singapore, 6Clinical Imaging Research Centre, A*Star-NUS
Evidence from cross-sectional functional connectivity (FC) studies on the effects of the apolipoprotein E-e4 allele (APOE-e4) on the brain functional organization in cognitively normal elderly is mixed. The possible synergistic effect of brain ageing and genetic risk factor on cognitive decline is also largely unknown. To investigate the longitudinal influence of APOE-e4 allele on age-related changes in brain FC and cognitive decline, 122 healthy older adults (aged 58-79; 42 APOE-e4 carriers) underwent task-free fMRI at baseline. 78 of them (16 carriers) had follow-ups every two years (over 2-4 years). Intra- and inter-network FCs were evaluated in the default mode network (DMN), the executive control network (ECN), and the salience network (SN). Linear mixed models were used to estimate the cross-sectional and longitudinal changes in brain function and cognition. Cross-sectionally, FC or cognitive did not differ significantly between APOE-e4 carriers and non-carriers. In contrast, longitudinally, APOE-e4 carriers had greater loss of functional segregation than non-carriers, evidenced by a steeper increase in FC between the DMN and the ECN. The brain-cognition association was also affected by APOE genotype. In younger elderly, higher FC between the DMN and the ECN was associated with greater decline in processing speed in both carriers and non-carriers. In contrast, in older elderly, the non-carriers continued to have the same negative correlation but carriers had the opposite trend. Therefore, APOE-e4 may alter biological ageing by accelerating the reduction of the segregation between high-level cognitive functional systems. The brain-cognition relationship is modulated by APOE genotype in an age-dependent manner.
Topic Area: EXECUTIVE PROCESSES: Development & aging