Integrating social science and behavioral genetics: testing the origin of socioeconomic disparities in depression using a genetically informed design.
OBJECTIVE
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.


METHODS
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.


RESULTS
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 (r(2) = -0.22). Co-twin control analyses indicated a protective effect of education and income on major depression even after accounting for genetic liability.


CONCLUSIONS
This study utilized a genetically informed design to address how social position relates to major depression. Results generally supported the social causation model.
Briana Mezuk is with the Division of Epidemiology, Department of Family Medicine and Population Health, and the Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, and the Research Center for Group Dynamics, Institute for Social Research, University of Michigan, Ann Arbor. John M. Myers is with the Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University. Kenneth S. Kendler is with the Department of Psychiatry and the Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University.
Briana
B
Mezuk
John M
JM
Myers
Kenneth S
KS
Kendler
D000328:Adult; D003865:Major Depressive Disorder / Q000191:economics / Q000453:epidemiology / Q000235:genetics*; D004522:Educational Status; D005260:Female; D059647:Gene-Environment Interaction; D036281:Genetic Research; D005824:Genetics, Behavioral; D006801:Humans; D007182:Income; D012107:Research Design; D012307:Risk Factors; D012937:Social Mobility; D012942:Social Sciences; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D014430:Twins, Monozygotic