A new study has provided new insights into the the genetic overlap among some psychiatric disorders, and can help explain why it’s not uncommon for several of these disorders to arise in the same individual. Most people who are diagnosed with some psychiatric disorder will also eventually be diagnosed with another one (or more) in their lifetime. Although the causes of mental health problems can be complex and involve environmental influences, genetic factors also play a significant role. This work, which was reported in Nature, has revealed more about the genetic underpinnings of fourteen mental health issues.
In this study, the researchers analyzed genetic and health data from more than 6 million people to look for genetic overlap among psychiatric disorders; about one million had a mental health issue while the remaining 5 million were unaffected. The investigators also focused on five families in which there was significant diagnostic overlap among mental health issues.
Small changes in the sequence of genes can have a biological effect, and many genetic variations have been associated with specific disorders. This work identified 428 genetic variants that are linked to more than one mental health disorder, and 101 chromosomal regions that were found to be variation ‘hotspots.’
The fourteen mental health issues could be grouped into five categories based on genetic commonalities. The compulsive disorder group included obsessive-compulsive disorder, anorexia nervosa and, to a lesser degree, Tourette disorder and anxiety disorders. The internalizing disorder group included anxiety, major depression, and post-traumatic stress disorder (PTSD). The neurodevelopmental disorders consisted of autism spectrum disorder, attention-deficit/hyperactivity disorder and Tourette disorder to a lesser degree. Another group was made up of various substance use or dependency disorders, and the final group included schizophrenia and bipolar disorder.
The highest degree of genetic overlap was seen among anxiety, depression, and PTSD–about 90% of the genetic risk for these disorders is thought to be shared. There was a 66% overlap among the genetic markers for schizophrenia and bipolar disorder.
There aren’t easy diagnostic tests for mental health problems, such as a blood or antigen test. So clinicians have to assess symptoms and patient characteristics, noted Kenneth Kendler, MD, a professor at Virginia Commonwealth University. But genetics may help us to understand how some of these disorders are connected.
Now, these findings could improve the classification or diagnostic standards for these disorders. The genes that were identified in this work can also reveal more about the cell types and functions that are related to mental health problems. It may also help scientists find better treatments.
Sources: Virginia Commonwealth University, Nature
