Genetic overlap between body weight and mental disorders

In a new study published in JAMA Psychiatry, researchers from NORMENT discovered a number of genetic variants that are linked to both body weight and severe mental illness. 

First authors Shahram Bahrami and Nils Eiel Steen and their team analyzed genetic data from more than 600.000 people with major depression, bipolar disorder, and schizophrenia from large study cohorts around the world. Using advanced statistical methods, genetic variants involved in increased body weight (high body mass index) and severe mental disorders were examined and compared.  

The study showed extensive genetic overlap between body mass index and psychiatric disorders, including 111 shared genetic variants. This finding suggests shared molecular mechanisms between weight regulation and mental illness, but there was also a striking difference between disorders. While the genetic risk variants for major depression and bipolar disorder mainly were associated with increased weight, most of the genetic variants in schizophrenia were related to reduced weight.

The results suggest that people with bipolar disorder and major depression have a genetic risk for increased body mass which together with diet, lifestyle and medication can explain the increased weight that many patients experience. The genetic architecture of schizophrenia, on the other hand, may be largely protective against weight gain. The large problem that many schizophrenia patients experience with weight gain seems to be due to non-genetic effects, such as life style and medication. These patients may have a genetic susceptibility to be thinner, which is in line with observations from studies of non-treated patients.

The study provides new insight into the link between body and brain, and identifies a high number of overlapping genetic variants. The findings also suggest that it is possible to develop prediction tools that can inform treatment choice based on metabolic risk in people with severe mental disorders.

Read about the paper on Overlapping genetic loci between BMI and mental health disorders


Bahrami S, Steen NE, Shadrin A, O’Connell K, Frei O, Bettella F, Wirgenes KV, Krull F, Fan CC, Dale AM, Smeland OB, Djurovic S, Andreassen OA. Shared genetic loci between body mass index and major psychiatric disorders. JAMA Psychiatry. Published online January 08, 2020. doi:10.1001/jamapsychiatry.2019.4188

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Shahram Bahrami. Photo: Kirsten Sjøwall


Nils Eiel Steen.
Photo: Kirsten Sjøwall


Published Jan. 13, 2020 10:21 AM - Last modified Jan. 13, 2020 10:21 AM