International research group finds genetic link among five major psychiatric diseases

A study published in The Lancet on Thursday reveals that a common genetic thread links five well-known psychiatric diseases: autism, attention deficit-hyperactivity disorder, bipolar disorder, major depressive disorder and schizophrenia.

The study was conducted by an international research collaboration, looking at the genomes of more than 60,000 patients of European ancestry. Scientists hope the findings will clear up how these diseases are classified, moving from describing symptoms to identifying underlying causes. And once other scientists dig into the data, there may be some progress made on treating these five diseases.

Dr. Jordan Smoller, one of the lead researchers on the study and associate vice chair in the department of psychiatry at Massachusetts General Hospital, said the researchers were surprised to find several regions of the genome common to all five diseases.

There’s very little information as yet about what these genetic triggers might actually do, though.

“This points us to some leads that really need to be followed up,” Smoller said. “One thing we might think of is there is some early, very basic alteration in some of the brain circuitry or these channels that give us a susceptibility to a broad range of psychiatric difficulties.”

To be sure, though, not everyone who has these genetic risk factors develops a mental illness, leading Smoller to wonder if they might just make the brain more susceptible to other environmental or physical influences.

“They only account for a small fraction of risk. One could have all of these genetic variances we identify in the paper and still not develop a disorder. But they do point us to new biology we hope one day will point us to opportunities for treatment,” he added.