Prominent Genetic Study Finds Lots of Links Between Various Psychiatric Disorders
Psychiatric disorders share many genetic variants, while neurological disorders appear more distinct, according to a new study from the Brainstorm Consortium, that represents 600 institutions worldwide.
Published last week, in Science, the study takes the broadest look yet at how genetic variation relates to brain disorders.
The results indicate that psychiatric disorders may have important molecular similarities that are not reflected in current diagnostic categories.
“This work is starting to reshape how we think about disorders in the brain,” said Dr. Ben Neale, Director of Population Genetics at Broad Institute of MIT and Harvard.
“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,” Neale added.
Dr. Neale led the study together with Dr. Aiden Corvin, Professor at Trinity College Dublin. Verneri Anttila, a Postdoc Research Fellow in Neale’s lab is first author.
Exploring these biological connections is challenging. The brain is a tricky organ to study directly, difficult to scan in detail, or ethically biopsy. And, because brain disorders often co-occur, it’s hard to untangle when one might be affecting the development of another.
To examine the biological overlap between these disorders, researchers must rely on genetics. For the current study, the team pooled their data to uncover genetic patterns across 25 psychiatric and neurological diseases. Because each genetic variant only contributes a tiny percentage of the risk for developing a given disorder, huge sample sizes are needed to separate reliable signals from noise.
The researchers 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 dataset ultimately included all GWAS consortia studying common brain disorders that the team could identify with sufficient sample sizes.
“We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine,” the scientists wrote.
Additionally, within the cognitive measures, the researchers were surprised to note 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. Neurological disorders, however, particularly Alzheimer’s and stroke, were negatively correlated with those same cognitive measures.
“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,” Anttila remarked.
“It was also surprising that the genetic factors related to many psychiatric disorders were positively correlated with educational attainment. We’ll need more work and even larger sample sizes to understand these connections,” he added.
The high degree of genetic correlation among many of the psychiatric disorders suggests that the current clinical categories do not accurately reflect the underlying biology, concluded the researchers.
The consortia have made their GWAS data accessible online, either freely available for download or by application.
They plan to examine additional traits and genetic variants to explore these patterns further, aiming to discover the relevant mechanisms and pathways that underlie and potentially link these disorders.