Interactions between the apolipoprotein E ε4 allele status and adverse childhood experiences on depressive symptoms in older adults

Background: The influence of childhood adversity on depression is modulated by genetic vulnerability. The apolipoprotein E epsilon 4 (APOE-epsilon 4) allele is a strong genetic risk factor for Alzheimer's disease (AD). Because late-life depressive symptoms could be a part of the preclinical course of AD, the APOE-epsilon 4 allele may contribute to depression in old age. Objective: The aim of this study was to evaluate whether an APOE-epsilon 4 carrier status was associated with depressive symptoms in older adults and to detect the gene-environment interaction between APOE-epsilon 4 status and childhood adversity in relation to depressive symptoms in old age. Method: The participants consisted of 137 older adults (age range 50-70) without any psychiatric history or clinically significant cognitive impairment. APOE genotypes and measures of childhood adversity and depressive symptoms were obtained. Results: There was a significant positive association between adverse childhood experiences (ACE) scores and depressive symptoms (B = 0.60; 95% CI = 0.26, 0.93 for a 1 score increase in ACE scores; p = 0.001). Although APOE-epsilon 4 status per se was not associated with depressive symptoms, there was a significant interaction of the ACE scores with the APOE genotype in relation to depressive symptoms (B = 0.78; 95% CI = 0.02, 1.55; p = 0.044). There was a significantly higher effect of childhood adversity on depressive symptoms in APOE-epsilon 4 carriers than non-carriers (t = 2.13, p = 0.035). Conclusions: Our results suggest that the APOE-epsilon 4 may modulate the association between childhood adversity and depressive symptoms in older adults. However, more research in a larger sample is needed to gain a better understanding of the relationship between the APOE-epsilon 4, childhood adversity, and depression.