title: Gene-behavior interaction of depressive symptoms and the apolipoprotein E {varepsilon}4 allele on cognitive decline.
abstract: OBJECTIVE
  Depressive symptoms and the apolipoprotein E (APOE) ε4 allele are independent risk factors for cognitive decline. However, it is not clear whether the presence of both depressive symptoms and the APOE ε4 allele increases cognitive decline.
  
  
  METHODS
  A prospective study of a population-based sample of 4150 (70% African American and 63% women) participants 65 years and older who were interviewed at 3-year intervals was conducted. Depressive symptoms were measured using the 10-item version of the Center for Epidemiologic Studies Depression scale, with each item coded as presence or absence of a symptom. The APOE genotype was ascertained by DNA samples collected during follow-up. Cognitive function was assessed at the initial and follow-up interviews (average follow-up of 9.2 years), using a standardized global cognitive score.
  
  
  RESULTS
  There were 1405 (34%) participants with one or more copies of the APOE ε4 allele. In participants with no depressive symptoms, cognitive function decreased by 0.0412 unit per year among those with no copies and 0.0704 unit per year among those with one or more copies of the APOE ε4 allele. For each additional symptom of depression, cognitive decline increased by 0.0021 unit per year among those with no copies and 0.0051 unit per year among those with one or more copies of the APOE ε4 allele. The three-way interaction of depressive symptoms, APOE ε4 allele, and time was significant (p = .021).
  
  
  CONCLUSIONS
  The association of depressive symptoms on cognitive decline was increased among participants with one or more copies of the APOE ε4 allele compared with those without the allele.
authors.affiliation: Ph., 1645 W Jackson Blvd, Suite 675, Chicago IL 60612. kumar_rajan@rush.edu.
authors.forename: Kumar B
authors.initials: KB
authors.lastname: Rajan
authors.forename: Robert S
authors.initials: RS
authors.lastname: Wilson
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Skarupski
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Mendes de Leon
authors.forename: Denis A
authors.initials: DA
authors.lastname: Evans
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data; D000368:Aged; D000483:Alleles; D053327:Apolipoprotein E4 / Q000235:genetics*; D003072:Cognition Disorders / Q000453:epidemiology* / Q000235:genetics / Q000523:psychology; D003863:Depression / Q000453:epidemiology* / Q000523:psychology; D018450:Disease Progression; D005260:Female; D005838:Genotype; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006801:Humans; D007361:Intelligence Tests / Q000706:statistics & numerical data; D007406:Interview, Psychological; D008019:Life Style; D016014:Linear Models; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012307:Risk Factors; D013997:Time Factors; D044465:White People / Q000706:statistics & numerical data
chemical_list: D053327:Apolipoprotein E4
keywords: APOE gene; cognitive decline; depressive symptoms; gene-behavior interaction