|| Checking for direct PDF access through Ovid
We tested 3 hypotheses-social causation, social drift, and common cause-regarding the origin of socioeconomic disparities in major depression and determined whether the relationship between socioeconomic status (SES) and major depression varied by genetic liability for major depression.Data were from a sample of female twins in the baseline Virginia Adult Twin Study of Psychiatric and Substance Use Disorders interviewed between 1987 and 1989 (n = 2153). We used logistic regression and structural equation twin models to evaluate these 3 hypotheses.Consistent with the social causation hypothesis, education (odds ratio [OR] = 0.78; 95% confidence interval [CI] = 0.66, 0.93; P < .01) and income (OR = 0.93; 95% CI = 0.89, 0.98; P < .01) were significantly related to past-year major depression. Upward social mobility was associated with lower risk of depression. There was no evidence that childhood SES was related to development of major depression (OR = 0.98; 95% CI = 0.89, 1.09; P > .1). Consistent with a common genetic cause, there was a negative correlation between the genetic components of major depression and education (r2 = -0.22). Co-twin control analyses indicated a protective effect of education and income on major depression even after accounting for genetic liability.This study utilized a genetically informed design to address how social position relates to major depression. Results generally supported the social causation model.