The role of genetics in personality and schizophrenia

Researchers have identified genes that influence both the risk for schizophrenia and the development of certain personality traits.

The work published late last month in the journal Scientific Reports, a Nature Research publication, follows on a study published late last year by the same group of scientists that identified six loci associated with personality traits.

That study found correlations between those traits and psychiatric disorders, but the work published this week confirms that there is more than just a correlation between certain personality traits and schizophrenia. There are genetic variants that influence both.

The findings also provide new insights into the genetic processes underlying schizophrenia and personality traits, according to the researchers.

And the research is consistent with what scientists have suspected all along, that certain personality traits and psychological disorders are related and share some genetic influences. Studies in recent years have shown correlations between psychiatric disorders and personality traits — measured on a spectrum known as the “Big Five” that includes neuroticism, extraversion, openness, agreeableness and conscientiousness.

While scientists have long believed that genetics plays a role in both personality and in the risk for mental illness, pinpointing which genes are involved has been difficult. In the past the limited size of genome wide association studies have stymied efforts to identify specific genetic variants associated with these conditions.

The breakthrough with these most recent studies is that researchers have been able to use what is called a meta-analysis to combine data from numerous sources and power their research with very large data sets. In this case researchers used data from about 60,000 23andMe customers who consented to participate in research as well as data from more than 80,000 individuals who are part of the Psychiatric Genomics Consortium (PGC) cohort.  The PGC unites investigators from around the world studying the genetics around psychiatric conditions such as bipolar disorder, major depressive disorder, and schizophrenia. The group has also become a sort of repository for data that can be used for these studies.

The researchers working on this latest study found six genetic variants shared between schizophrenia and openness to new experiences. They found three variants that influence both schizophrenia and the personality trait of neuroticism. Although these associations were found using a meta-analysis of the combined 23andMe and PGC data, the researchers also demonstrated that these results could be replicated in the individual cohorts..

“Altogether, our study provides new insights into the genetic architecture of schizophrenia and personality traits,” the researchers said in the paper. “The findings comply with accumulating evidence from genetics and neuroscience suggesting that mental disorders are not discontinuous with normal variation in neurobiological and behavioral dimensions.”

You can read the paper at Scientific Reports here.