08 Jan Overlapping Genetic Loci Between BMI and Mental Health Disorders

MedicalResearch.com Interview with:

Dr. Bahrami

Shahram Bahrami, PhD
NORMENT Centre, Institute of Clinical Medicine
Division of Mental Health and Addiction
Oslo University Hospital
Oslo, Norway 

MedicalResearch.com: What is the background for this study?

Response: We know that patients with severe mental disorders such as schizophrenia, bipolar disorder and major depression have shorter life span than the rest of the population, largely due to comorbid cardiovascular diseases. The increased risk seems related to lifestyle including diet and physical activity and medicines, while the mechanisms are not fully understood. Different studies have shown increased weight (high body mass index) in many people with mental disorders. Yet very little is known about genetic variants jointly in influencing major psychiatric disorders and body mass index. Thus, we investigated if there are overlapping genetic risk variants between body mass index and the mental disorders schizophrenia, bipolar disorders and major depression. 

 MedicalResearch.com: What are the main findings? 

Response:  The main finding from our study is that we identified overlapping genetic risk variants between body mass index and the severe mental disorders schizophrenia, bipolar disorders and major depression.

Patients with bipolar disorders 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. In schizophrenia, on the other hand, the large problem many patients are experiencing with weight gain seems to be due to non-genetic effects, such as life style and medication. In fact, people with schizophrenia have a genetic susceptibility to be thinner, which is in line with observations from non-treated patients

MedicalResearch.com: What should readers take away from your report?

•  There are many overlapping genetic risk variants between body mass index and the severe mental disorders schizophrenia, bipolar disorders and major depression. However, while the risk variants for major depression and bipolar disorder mostly lead to increased weight, in schizophrenia most of the shared genetic variants are associated with reduced weight.
• People with bipolar disorders 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. This is important information in a clinical setting.

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: Further studies are required to determine the true causal variants underlying the shared associations detected here, and whether the same causal variants are involved in body mass index and severe mental disorders. Furthermore, due to the inherent case control design of the GWASs, selection bias with effects on the associations cannot be fully ruled out. However, the risk seems to be low for single genetic variants. it is also challenging to evaluate small effect sizes and to speculate about molecular mechanisms behind the effective variants when examining such potentially overlapping phenotypes.

MedicalResearch.com: Is there anything else you would like to add?

Response: We are currently working to disentangle genetic susceptibility and environmental risk factors for comorbid cardiovascular risk factors in large Nordic registry and biobank samples.

Citation:

Bahrami S, Steen NE, Shadrin A, et al. Shared Genetic Loci Between Body Mass Index and Major Psychiatric Disorders: A Genome-wide Association Study. JAMA Psychiatry. Published online January 08, 2020. doi:https://doi.org/10.1001/jamapsychiatry.2019.4188

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Last Updated on January 8, 2020 by Marie Benz MD FAAD