title: Prospective associations of exercise and depressive symptoms in older adults: the role of apolipoprotein E4.
abstract: Exercise is associated with reduced risk of depressive symptoms at older ages, while recent work suggests that the apolipoprotein E type 4 allele (APOE-e4) may increase risk. There are no studies of whether APOE-e4 moderates the relationship between exercise and later life depressive symptoms. This study aimed to explore whether the prospective associations between exercise and subsequent depressive symptoms were distinct between APOE-e4 carriers and non-carriers using nationwide data.
  
  
  
  Data from 639 participants (mean age = 66.14, SD = 7.26) in 2000 with 6 years of follow-up were studied. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression Scale. Exercise and the APOE genotype were also assessed at baseline. Negative binomial regression models were conducted to examine the combined effects of exercise and APOE-e4 status on subsequent depressive symptoms when controlling for baseline depressive symptoms and other covariates. Sensitivity analyses to test for confounding, reverse causality, and attrition were conducted.
  
  
  
  Among APOE-e4 carriers, there was no significant difference in depressive symptoms between high active and low active groups. In contrast, high active APOE-e4 non-carriers had fewer depressive symptoms than low active APOE-e4 non-carriers. The beneficial effect of exercise on depressive symptoms is restricted to APOE-e4 non-carriers. Sensitivity analyses provided further support for the robustness of these findings.
  
  
  
  This is the first prospective study investigating whether APOE-e4 moderates the association between exercise and depressive symptoms. It proposes that genetic variation in APOE may influence the effect of exercise on depressive symptoms.
authors.affiliation: Graduate Institute of Sports and Health, National Changhua University of Education, Changhua, Taiwan, Republic of China.|Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Po-Wen
authors.initials: PW
authors.lastname: Ku
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Steptoe
authors.affiliation: Department of Epidemiology and Public Health, University College London, London, UK. ljchen@ntupes.edu.tw.|Department of Exercise Health Science, National Taiwan University of Sport, No. 271, Lixing Road, Taichung, 404, Taiwan, Republic of China. ljchen@ntupes.edu.tw.
authors.forename: Li-Jung
authors.initials: LJ
authors.lastname: Chen
mesh_terms: D000368:Aged; D000375:Aging; D053327:Apolipoprotein E4 / Q000378:metabolism*; D003863:Depression / Q000628:therapy*; D015444:Exercise / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011788:Quality of Life / Q000523:psychology*; D012307:Risk Factors
chemical_list: D053327:Apolipoprotein E4
keywords: Aging; Depression; Mental health; Moderation; Physical activity