Summary: Researchers have found shared genetic support for cannabis use and mental illnesses such as schizophrenia and bipolar disorder. Employing advanced statistical modeling, the study revealed complex genetic variants that increase or decrease susceptibility to these conditions.
These findings may contribute to personalized prevention measures and intervention strategies. Additionally, an improved understanding of this genetic overlap may aid in more specific treatment plans.
Key facts:
- The study identified shared genetic factors that increase risk for both cannabis use and certain mental disorders.
- Some genetic variants may have the opposite effect—increasing the likelihood of cannabis use while decreasing the risk of developing schizophrenia or bipolar disorder.
- These findings may improve prevention measures, intervention strategies, and more targeted treatments.
Source: University of Oslo
A new study from the University of Oslo Lancet Psychiatryreported a common genetic basis for cannabis use and psychiatric disorders, including schizophrenia and bipolar disorder.
These findings may indicate that segments of the population are at high risk for both cannabis use and mental illness based on their genetic predisposition.
There has been much debate about the relationship between cannabis use and mental illness. Cannabis is a psychoactive drug that sometimes produces psychotic-like symptoms.
Additionally, rates of cannabis use are high among patients with psychosis-related disorders such as schizophrenia and bipolar disorder.
Genetic factors play a large role in determining a person’s risk of developing mental disorders or using cannabis. Some genetic variants associated with cannabis use have been linked to psychiatric disorders.
This recent study by Dr. Weiqiu Cheng and Nadine Parker provide evidence that shared genetic factors underlie this relationship.
“This study shows that there is a common genetic basis for both cannabis use and susceptibility to certain psychiatric disorders. These findings may indicate that segments of the population are at high risk for both cannabis use and psychiatric disorders based on their genetic predisposition,” said lead author Weiqiu Cheng.
Using advanced statistical modeling, the study found that most shared variants increased the risk of both cannabis use and schizophrenia or bipolar disorder.
Still, there are some genetic variants with opposite effects, which increase the risk of cannabis use and decrease the risk of the two mental disorders, suggesting a complex relationship.
“These findings are important because the complex relationship between cannabis use and these diseases may be driven not only by cannabis use itself, but by shared genetic susceptibility,” said researcher Nadine Parker.
Cannabis is used medicinally for pain relief and in some regions of the world as an anti-depressant. Also, a component of cannabis is being considered as a potential treatment for psychosis.
“Genetic differences shared with opposite effects may suggest the existence of biological mechanisms that support the beneficial effects of cannabis,” the researchers said.
These new findings have several important clinical implications.
First, this information can lead to personalized care, including prevention and intervention measures for high-risk individuals. This may include reduced cannabis use among individuals with a high genetic risk for schizophrenia and bipolar disorder.
Second, future studies investigating the biological effects of shared genetic variants may contribute to the development of more targeted treatment efforts.
Finally, improved knowledge of genetic overlap may be used to guide patients toward more specific treatment plans.
So genetics and mental health research news
Author: Press office
Source: University of Oslo
Contact: Press Office – University of Oslo
Image: Image credited to Neuroscience News.
Preliminary study: Closed access.
“Association between Cannabis Use, Schizophrenia, and Bipolar Disorder: A Genetically Validated Study” by Weiqiu Cheng et al. Lancet Psychiatry
Draft
Association between Cannabis Use, Schizophrenia, and Bipolar Disorder: A Genetically Validated Study
Background
The relationship between psychotic disorders and cannabis use is controversial. An underlying genetic risk is one possible explanation. We investigated the genetic association between psychotic disorders (schizophrenia and bipolar disorder) and cannabis phenotypes (lifetime cannabis use and cannabis use disorder).
Methods
We used genome-wide association summary statistics from individuals of European ancestry from the Psychiatric Genomics Consortium, the UK Biobank, and the International Cannabis Consortium. We estimated the heritability, polygenicity, and detectability of each phenotype. We performed genome-wide and local genetic correlations. Shared loci were identified and mapped to genes, which were tested for functional enrichment. Common genetic liabilities for psychotic disorders and cannabis phenotypes were explored using causal analyzes and polygenic effects using the Norwegian Thematic Organized Psychosis Group.
Findings
Psychotic disorders were more heritable than cannabis phenotypes and more polygenic than cannabis use disorders. We observed positive genome-wide genetic associations with positive and negative local genetic associations between psychotic disorders and cannabis phenotypes (range 0·22–0·35). Between three and 27 common loci have been identified for psychotic disorder and cannabis phenotype pairs. Enrichment of map genes includes neurons and olfactory cells as well as drug-gene targets for nicotine, alcohol and duloxetine.
Psychotic disorder showed a causal effect on cannabis phenotypes, and lifetime cannabis use had a causal effect on bipolar disorder. Of 2181 European participants from the Norwegian Thematic Organized Psychosis Group who were included in polygenic risk score analyses, 1060 (48·6%) were women and 1121 (51·4%) were men (mean age 33·1 years). [SD 11·8]). 400 participants had bipolar disorder, 697 had schizophrenia, and 1044 were healthy controls.
In this sample, polygenic effects for cannabis phenotypes independently predicted psychotic disorders and improved prediction over and above polygenic effects for psychotic disorders.
Interpretation
A subgroup of individuals may have a higher genetic risk for developing psychotic disorders and using cannabis. This finding supports public health efforts to reduce cannabis use, particularly among high-risk individuals or those with mental illness. Identified common sites and functional implications may facilitate the development of new therapies.
Financial support
US National Institutes of Health, Research Council Norway, South-East Regional Health Authority, Stiftelsen Christian Gerhard Jebsen, EEA-RO-NO-2018–0535, EU Horizon 2020 Research and Innovation Program, Marie Sklodowska-Curie Actions, and Oslo Life Sciences University.