MEMORY PERFORMANCE OVER TIME IS MEDIATED BY SUBJECTIVE MEMORY COMPLAINT AND APOE-E4 CARRIAGE

Abstract

Possessing at least one APOE-e4 allele is a known risk factor for AD that has been associated with episodic memory decline. Subjective memory complaint (SMC) has also been proposed as a marker for early detection; however, no consistent relationship has been shown between SMC and objective cognitive decline. As SMC is considered in the diagnosis of MCI/AD, it is important to elucidate this association to increase its predictive value and diagnostic utility. This study hypothesizes that there is an interaction between SMC, APOE-e4 carriage and memory performance over time. Participants were from the Women's Healthy Ageing Project, a prospective longitudinal study of Australian women (n=165). The women were aged 64–77, and a follow up assessment was conducted approximately 2 years later. APOE-e4 genotype was determined from blood samples and treated as a dichotomous variable, and participants were asked about SMC. A three-way mixed ANOVA was conducted using 2 between-subjects factors (SMC, APOE-e4 status), 1 within-subjects factor (time point) and 3 covariates (age, education, HADS anxiety), with CVLT-II long-delay free recall score as the dependent measure. APOE-e4 carriers were not more likely to report SMC. There was a significant main effect of APOE-e4 status with SMC, which was non-significant with individuals reporting no SMC. SMC and APOE-e4 status showed a significant two-way interaction after adjustments (p<0.0001), and a 3-way interaction with time point was also observed (p<0.0001). Memory complainers with at least one APOE-e4 allele exhibit the greatest rate of decline between the two time points; the greatest increase was observed in non-carriers with no SMC. APOE-e4 carriers with no memory complaint maintained stable memory performance.