a1 Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA, USA
a2 Department of Psychiatry, Virginia Commonwealth University, Richmond, VA, USA
a3 Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA, USA
Background Certain personality traits have long been suspected to reflect an enduring vulnerability to major depression (MD) in part because of shared genetic risk factors. Although many have agreed that normative personality is well captured by the ‘Big-Five’ personality traits of Openness (O), Conscientiousness (C), Extraversion (E), Agreeableness (A) and Neuroticism (N), to date genetically informative studies have only examined the relationship between MD and N and E.
Method Questionnaires were completed on a website, yielding a sample of 44 112 subjects including both members of 542 same-sex twin pairs. Personality was measured by the Big Five Inventory. Structural modeling was performed by Mx.
Results Three of the big-five personality traits – O, E and A – had small phenotypic associations with risk for MD and small genetic correlations. Two traits – N and C – had stronger phenotypic associations (positive for N and negative for C) with the following estimates of the genetic correlation with MD: +0.43 for N and −0.36 for C. N and C were moderately negatively correlated. Controlling for N reduced the genetic correlation between C and MD more than controlling for C reduced the genetic correlation between N and MD.
Conclusions A large proportion of the genetic risk for MD that is expressed via personality is captured by N, with a modest amount due to C, and small amounts from O, E and A.
(Received October 23 2008)
(Revised June 16 2009)
(Accepted June 24 2009)
(Online publication September 07 2009)
c1 Author for correspondence: K. S. Kendler, M.D., Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Box 980126, Richmond, VA 23298-0126, USA. (Email: firstname.lastname@example.org)