In a groundbreaking study, researchers from the Centre for Precision Psychiatry at the University of Oslo and Oslo University Hospital have discovered extensive genetic links between neurological disorders like migraine, stroke and epilepsy, and psychiatric illnesses such as schizophrenia and depression. Published in Nature Neuroscience, this research challenges longstanding boundaries between neurology and psychiatry and points to the need for more integrated approaches to brain disorders.

"We found that psychiatric and neurological disorders share genetic risk factors to a greater extent than previously recognised. This suggests that they may partly arise from the same underlying biology, contrasting the traditional view that they are separate disease entities. Importantly, the genetic risk was closely linked to brain biology," states Olav Bjerkehagen Smeland, psychiatrist and first author.

Nearly one million cases analysed
The team analysed genetic data from close to one million individuals with a wide range of psychiatric or neurological conditions. This large dataset made it possible to map both shared and disorder-specific genetic signals. “The findings are consistent with what we see clinically: patients often present with overlapping symptoms across neurology and psychiatry”, says Professor Ole Andreassen, leader of the Centre for Precision Psychiatry. “Our results support a more unified view of neurological and psychiatric disorders».

Toward more holistic care
According to Smeland, the study suggests that patients could benefit from treatment strategies that take both biological and mental aspects into account. "We should ask whether patients receive the best care when neurology and psychiatry operate in parallel rather than together”, he says

Genes and their varied influence on brain biology
While the study found substantial genetic overlap, the disorders still displayed partly distinct biological signatures. "For instance, genetic susceptibility to stroke was associated with risk factors for thrombosis, while epilepsy was connected to neurons – the brain’s nerve cells. The genetic risk for Alzheimer's disease and multiple sclerosis, by contrast, was tied to the immune system, which also influences the nervous system. The genetic risk for psychiatric illnesses was consistently linked to neurons. “This tells us that neurological and psychiatric disorders are heterogeneous, but may still be connected within a common biological framework,” Smeland explains.

Future directions
While distinctions between neurological and psychiatric disorders do exist, this study paves the way for a more holistic understanding of brain disorders. "I believe that improved knowledge exchange and closer collaboration between psychiatry and neurology could substantially benefit patients, " Smeland states.

About Centre for Precision Psychiatry
The Centre for Precision Psychiatry at the University of Oslo uses large-scale data and advanced analytical methods to identify causes and risk factors in severe mental illness. The aim is to improve prevention and diagnostics, and to develop more targeted treatment.