LAUSR

Background The apolipoprotein E ε4 allele (APOE*ε4) is indicated as a risk for Alzheimer's disease and other age-related diseases. The risk attributable to APOE*ε4 for depression is less clear and may be because of confounding of the relationship between dementia and depression. Aims We examined the risk of APOE* ε4 for incident depression and depressive symptomology over a 12-year period across the adult lifespan. Method Participants were from the Personality and Total Health Through Life study, aged 20 to 24 (n = 1420), 40 to 44 (n = 1592) or 60–64 (n = 1768) at baseline, and interviewed every 4 years since 1999. Ethnicities other than White, those without genotyping and those with depression at baseline, or who reported strokes and scores on the Mini-Mental State Examination <27 at any observation, were excluded. Results Over the study period, there was no evidence that APOE*ε4+ was a risk factor for depression, including any depression (odds ratio (OR) = 0.94, 95% CI 0.77–1.16, P = 0.573), major depression (OR = 0.96, 95% CI 0.60–1.53, P = 0.860), minor depression (OR = 0.94, 95% CI 0.67–1.30, P = 0.695) or depressive symptomology (incidence rate ratio (IRR) = 1.02, 95% CI 0.97–1.08, P = 0.451). APOE*ε4 was unrelated to incident depression. Findings were consistent for all age cohorts. Conclusions Among cognitively intact Australian adults who were free of depression at baseline, there was little evidence that APOE*ε4+ carriers are at increased risk for depression over a 12-year period among those who are cognitively intact.