Moderating effect of apolipoprotein genotype on loneliness leading to depressive symptoms in Chinese older adults

Objective: Depressive symptoms, which are both common and heritable, are important indicators of the extent of general well-being and health in old age. Identifying risk factors for depressive symptoms may lead to improved intervention and effective prevention. Both the presence of the apolipoprotein (APOE) genotype and loneliness are associated with later life symptoms of depression, and all three share a neuroendocrine signature, namely altered activity in the hypothalamic-pituitary-adrenal axis. The authors expected a positive association of loneliness with depressive symptoms, a negative link between APOE ɛ2 with depressive symptoms, and a significant genotype-environment interaction between loneliness (the social environment) and APOE ɛ2 on symptoms of depression. Design: This was a cross-sectional observational study. Setting and Participants: A population-based sample of 979 Chinese people from Taiwan aged 54 years and older was examined. Measurements: A short-form of the Center for Epidemiologic Studies of Depression Scale was used and the genotype of APOE was obtained. Results: The interaction between loneliness and APOE ɛ2 was found to be negatively associated with depressive symptoms in adjusted regression models. Loneliness was also positively correlated with symptoms of depression. Conclusions: These data suggest that the APOE ɛ2 genotype decreases vulnerability to symptoms of depression in the presence of a social stressor, namely loneliness in this case, and has implications for the enhancement of well-being among older adults. Future studies are needed to delineate the mechanism underlying this gene-environment interaction. Copyright © 2010 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.