Researchers have identified six regions of the human genome that are significantly linked to personality traits, and some show significant correlations to certain psychiatric disorders as well.
The study, conducted by researchers at the University of California San Diego School of Medicine, is based on a meta-analysis of genome-wide association studies (GWAS). The results are published in the journal Nature Genetics.
The findings show strong genetic correlations between attention-deficit hyperactivity disorder (ADHD) and the personality trait of extraversion. Schizophrenia and bipolar disorder were associated with having an openness to experience. Neuroticism was linked to internalized psychopathologies, such as depression and anxiety.
“Although personality traits are heritable, it has been difficult to characterize genetic variants associated with personality until recent, large-scale GWAS,” said senior author Chi-Hua Chen, Ph.D., assistant professor in the Department of Radiology at University of California, San Diego School of Medicine.
“We identified genetic variants linked to extraversion and neuroticism personality traits,” said Chen.
“Our study is in an early stage for genetic research in personality and many more genetic variants associated with personality traits are to be discovered. We found genetic correlations between personality traits and psychiatric disorders, but specific variants underlying the correlations are unknown.”
Past meta-analyses of twin and family studies have attributed approximately 40 percent of variance in personality to genetic factors. Researchers typically use five psychological factors to measure individual differences in personality. These include the following: extraversion, neuroticism, agreeableness, conscientiousness and openness to experience.
- Extraversion (versus introversion) reflects talkativeness, assertiveness, and a high activity level;
- Neuroticism (versus emotional stability) reflects negative affect, such as anxiety and depression;
- Agreeableness (versus antagonism) measures cooperativeness and compassion;
- Conscientiousness (versus undependability) indicates diligence and self-discipline;
- Openness to experience (versus being closed to experience) suggests intellectual curiosity and creativity.
Psychologists define personality phenotypes — sets of observable characteristics — based on quantitative scoring of these five factors. GWAS, which look for genetic variations across a large sampling of people, have discovered several variants associated with these traits.
For the new meta-analysis, the researchers analyzed genetic variations among the five personality traits and six psychiatric disorders, using data from 23andMe, a privately held personal genomics and biotechnology company.