The Puzzle of Co-occurring Disorders

A large international team of⁢ scientists is shedding new light ​on a long-standing puzzle in mental health: why many people are diagnosed‌ with more than one psychiatric disorder over their lifetime. In research published December 10 in the journal Nature, the ​group presents ⁤the most extensive⁣ and⁤ detailed investigation so far into the shared genetic foundations of 14 psychiatric conditions.

The work was led by the Psychiatric Genomics‍ Consortium’s Cross-Disorder Working Group. The group is co-chaired by Kenneth Kendler, M.D., a professor in⁤ the Department‌ of Psychiatry ⁢at Virginia Commonwealth University’s School⁣ of Medicine, and Jordan Smoller, M.D., ⁣a professor‍ in the Department of Psychiatry at⁣ Harvard Medical School.

For most people diagnosed with a psychiatric disorder, that diagnosis is rarely the only one they‌ will recieve. Many go on too develop a second or even third condition,which complicates how mental illnesses are classified and‍ treated.Life experiences and environment clearly shape mental health risk, but genetics also‍ play⁢ an crucial role in determining why disorders so often overlap.

To better‌ understand those genetic influences, researchers⁢ analyzed⁢ data from more than⁢ 6 ‌million people. Their findings ⁤reveal that the​ 14⁣ psychiatric disorders studied are not genetically isolated. Rather, they fall into five broad groups‍ that share substantial genetic similarities. This clearer ‌picture of genetic overlap could eventually help clinicians tailor care more effectively for ‍patients with⁣ complex diagnoses.

Unraveling the ‌Genetic Landscape

“Psychiatry is‌ the only medical specialty​ with no definitive laboratory tests.​ We can’t give​ a blood test to ​tell weather someone has depression — we have to rely on symptoms and signs. And that’s true for almost every psychiatric disorder,” said Kendler, a world-renowned researcher for his ⁣pioneering studies in psychiatric genetics. “Genetics ⁢is a‌ developing tool that allows us to understand the relationships between disorders.” VCU News

The 14 disorders examined in the study were: attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, bipolar ⁢disorder,‌ major depressive disorder,⁣ eating disorders, intellectual disability, obsessive-compulsive ‍disorder, post-traumatic stress disorder (PTSD), ‌schizophrenia, and several other related conditions. Nature

Researchers used genome-wide association studies (GWAS) to identify common genetic variants associated with⁣ each disorder. ‍GWAS involves scanning the genomes of many⁣ people to look for genetic markers that appear more often ⁢in people with a particular condition⁤ than in people without it. The analysis ⁢revealed that these disorders aren’t entirely distinct at the genetic level.

The Five Genetic Groupings

The study identified five broad groupings based on shared genetic architecture: