A new study published in the journal Cell has found new evidence to a genetic map of psychiatric disorders.
Researchers from the University of Barcelona, Spain, looked at nearly 230,000 patients and identified 109 genetic variants that are linked to eight mental health disorders, including autism, ADHD, depression, bipolar disorder, schizophrenia, obsessive-compulsive disorder (OCD), and Tourette Syndrome.
Dr. Bru Cormand from the University of Barcelona said, “Those disorders listed in the same group tend to share more risk genetic factors between them than with other groups. Moreover, we saw that these groups built on the basis of genetic criteria match with the clinical output.”
“However, the new study does not put emphasis on the genes shared by members of a particular group but on the genes shared by the highest number of disorders,” continued Dr. Cormand.
He added, “That is, those factors that would somehow give way to a ‘sensitive’ brain, more likely to suffer from any psychiatric disorder. And the fact that this could be one or another disorder would depend on specific genetic factors, not forgetting about the environmental factors.”
The study findings showed that a gene related to the development of the nervous system, called the DCC gene, is one of the risk factors of all eight psychiatric disorders. The study also found that another gene called RBOX1 is associated with seven out of eight mental health disorders.
The researchers found that depression and ADHD share 44 percent of those genetic risk factors, while schizophrenia and bipolar disorder share 70 percent each.
Researcher Dr. Joseph Antoni Ramos-Quiroga said, “These results help people with ADHD so they can understand the disorder and also why they can suffer from depression more frequently.”
“Furthermore, this is new scientific evidence that ADHD can persist over life, and be present in adults. We hope this helps to reduce the social stigma regarding ADHD and other mental illnesses,” he added.
Apart from genetic variants, the researchers also looked at the impact of gene expression.
Another researcher Dr. Raquel Rabionet said, “In the study, we identified eleven areas of the genome in which the effects are opposed in different pairs of disorders; that is, protection in one case, and susceptibility in the other.”
“This could make sense in some instances in which there would be a genetic variant with contrary effects in ADHD — a disorder usually related to obesity — and anorexia,” Dr. Rabionet continued. “However, regarding the neurodevelopmental disorders such as autism and schizophrenia, there are genetic variants with opposite effects and others that work in the same direction,” he added. “This suggests that the genetics of psychiatric disorders is more complex than we thought, and we are still far from solving this puzzle.”