Schizophenia, bipolar disorder may be genetic: Study

Scientists have found that some psychiatric disorders like schizophrenia, bipolar disorder may be genetic, whereas neurological disorders like Parkinson's or Alzheimer's, appeared more distinct.

The study indicated that psychiatric disorders are likely to have important similarities at a molecular level, which current diagnostic categories do not reflect.

"This work is starting to re-shape how we think about disorders of the brain. If we can uncover the genetic influences and patterns of overlap between different disorders, then we might be able to better understand the root causes of these conditions -- and potentially identify specific mechanisms appropriate for tailored treatments," said lead co-senior author, Ben Neale from Stanley Centre at Broad Institute of MIT and Harvard in Massachusetts.

In the study published in the journal Science, the team measured the amount of genetic overlap across the disorders using genome-wide association studies (GWAS) of 265,218 patients and 784,643 controls.

They also examined the relationships between brain disorders and 17 physical or cognitive measures, such as years of education, from 1,191,588 individuals.

The results showed widespread genetic overlap across different types of psychiatric disorders, particularly between attention-deficit/hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder and schizophrenia. 

The data also indicated strong overlap between anorexia nervosa and obsessive-compulsive disorder (OCD), as well as between OCD and Tourette syndrome.

Conversely, neurological disorders except migraine, which was genetically correlated to ADHD, major depressive disorder, and Tourette syndrome, appeared to be distinct.

Further, they noted that genetic factors predisposing individuals to certain psychiatric disorders -- namely anorexia, autism, bipolar, and OCD -- were significantly correlated with factors associated with higher childhood cognitive measures, including more years of education and college attainment.

"We were surprised that genetic factors of some neurological diseases, normally associated with the elderly, were negatively linked to genetic factors affecting early cognitive measures. It was also surprising that the genetic factors related to many psychiatric disorders were positively correlated with educational attainment," said first author, Verneri Anttila from the varsity.