Neuroticism polygenic risk score is associated with 20-year average depressive symptoms for Whites but not Blacks

Background. Black-White differences are reported in social, psychological, behavioral, medical, and biological correlates of depression. This study was conducted to compare Black and White older adults for the association between neuroticism polygenic risk score (N-PRS) and chronicity of depressive symptoms over 20 years. Methods. Data came from the Health and Retirement Study (HRS), 1990 – 2012, a nationally representative sample of Americans above age 50. Current analysis followed 9,249 individuals (7,924 Whites and 1,325 Blacks) for up to 22 years. Depressive symptoms were measured every two years between 1992 and 2012 using the 8-item Center for Epidemiological Studies-Depression Scale (CES-D-8). The independent variable was N-PRS. The dependent variable was average depressive symptoms between 1992 and 2012. Linear regression was used for data analysis.
Results. In the pooled sample, higher N-PRS was associated with higher average depressive symptoms over the 20-year follow up period [b=0.01, 95%CI=0.00 to 0.04], net of all covariates. We also found an interaction between race and N-PRS [b=-0.02, 95%CI=-0.03 to 0.00], suggesting a stronger effect of N-PRS on 20-year average depressive symptoms for Whites than Blacks. Based on our race-specific linear regression models, higher N-PRS was associated with higher depressive symptoms from 1992 to 2012 for Whites [b=0.01, 95%CI=0.01 to 0.02] but not Blacks [b=0.00, 95%CI=-0.02 to 0.02].
Conclusion. Black and White older adults may differ in the salience of the existing N-PRS for depressive symptoms, which better reflects the burden of depression for Whites than Blacks. This may be because the existing PRSs are derived from mostly or exclusively White samples, limiting their applicability in other race groups. Racial variation in psychosocial, clinical, and biological correlates of depression needs further research.