Associations between Verbal Memory Performance and Regional Brain Volumes Differ by APOE4 Carrier Status in Midlife Women

Abstract

AbstractBackgroundAPOE4 genotype is a stronger risk factor for Alzheimer’s disease (AD) in women than men, and its influence on memory and AD biomarkers differs by disease stage. Among cognitively normal older APOE4 carriers, APOE4 status influences memory similarly in males and females but adversely influences hippocampal volume in males. The effect of APOE4 status on regional brain volumes earlier in life, and in relation to memory, are less well understood. We examined whether associations between verbal memory performance and regional brain volumes differed by APOE4 status in cognitively normal midlife women. We hypothesized that APOE4 carriers would show weaker associations between memory performance and brain volumes than non‐carriers, particularly in the temporal lobe.MethodParticipants were enrolled in MsBrain, a cohort study of midlife women. Verbal memory was assessed with the California Verbal Learning Test (CVLT‐II). Cortical thickness was measured and segmented by FreeSurfer using individual T1w MPRAGE images. Multiple regressions were conducted to determine associations between memory (learning, free recall) and regional brain volumes by APOE4 status (carriers versus non‐carriers), controlling for age, education, and race.ResultIn 148 cognitively normal postmenopausal women (mean age = 59.17 years, 84.4% white, n = 37 APOE4 carriers), APOE4 status had no main effect on CVLT‐II measures or brain volumes, except the volume of the left supramarginal gyrus. However, APOE4 status modified the magnitude of association between verbal memory and brain volumes, specifically the association between: a) verbal learning and volume in the left caudal middle frontal gyrus (CMFG), left isthmus cingulate gyrus, left parahippocampal gyrus, left insula, right precuneus, right lateral orbitofrontal gyrus (LOG), and right temporal pole (TP); and b) free recall and volume in the left CMFG, right LOG, right posterior cingulate gyrus, and right TP. The direction of the associations between verbal memory and brain volumes was positive in non‐carriers and negative in carriers.ConclusionIn cognitively normal midlife women, APOE4 carrier status may influence the extent to which the hippocampal, temporal, and frontal lobe structures support verbal memory performance. This subtle effect may emerge before the main effect of this genetic risk factor on brain volume and memory.