A multilevel analysis of the influence of Apolipoprotein E genotypes on depressive symptoms in late-life moderated by the environment

Objective: This study aimed to clarify the relationship between the APOE alleles and depressive symptoms of older adults, considering individual characteristics and the effect of neighborhood environment. Methods: Using a multilevel, stratified sampling strategy, 500 elders were recruited from official household records. Depressive symptoms were assessed using the Taiwanese Depression Questionnaire [TDQ]. Cognitive function was assessed by the Short Portable Mental Status Questionnaire [SPMSQ]. Blood samples were collected for the determination of the Apolipoprotein E [APOE] polymorphism. Perceived neighborhood experience was brought together using the Neighborhood Quality Index [NQI]. Results: Three hundred and three subjects (58.8% male, with a mean age of 69.2 [SD=2.7] years) completed all questionnaires and the collection of blood samples. Risk factors for depressive symptoms of elders included lower educational level, cognitive impairment, having 2 or more chronic diseases, and having the APOE epsilon 4 allele. In the 2-level model with individual characteristics and neighborhood environmental factors, the effect of the APOE e4 allele on depressive symptoms was significantly attenuated. Conclusions: The APOE epsilon 4 allele is correlated with depressive symptoms among older adults, but moderated by neighborhood environmental factors. (c) 2007 Elsevier Inc. All rights reserved.