In what researchers call a “groundbreaking discovery,” specific genes that cause addiction to marijuana have been identified, and it turns out that some of them can increase the risk for depression and schizophrenia. The discovery could help shed some light as to why up to 90% of people with marijuana addiction also suffer from psychiatric conditions or other addictions.
To come to this conclusion, researchers, led by Joel Gelernter, a Yale psychiatrist analyzed the genes of up to 15,000 individuals from three different groups in a bid to establish the connection between gene composition and various addictions. Between 18% and 36% people in each group had a cannabis dependence. The team concentrated on genetic variations known as single nucleotide polymorphisms (SNPs) that are associated with symptoms of marijuana addiction.
The researchers found three genetic variants in the subjects linked with addiction to marijuana. One of the variants was located in a gene that regulates the level of calcium in the body. Repeated studies have already established that fluctuation of calcium concentrations in the body is an indicator of substance use disorders such as opioid addiction.
Another genetic variation located in a gene known as CSMD1 was also found in participants with marijuana dependence. The variant is linked to the growth of the central nervous system. Surprisingly, genetic variations found in CSMD1 are associated with schizophrenia risk. Following the discovery, Gelernter said, “We were surprised to find a genetic risk overlap between cannabis dependence and major depression.”
“We were surprised to find a genetic risk overlap between cannabis dependence and major depression.” – Gelernter, following the discovery.
While previous studies have associated marijuana addiction and increase the risk of schizophrenia, this is the first study to show the specific genes that cause the addition and further explain why addicts tend to have psychiatric disorders. It is imperative to mention that this study only established the link between genetic variations and symptoms of marijuana addiction and cannot prove that these genetic variations lead to marijuana dependence.
Additionally, even though the study seems to point to the fact that marijuana addiction, depression, and schizophrenia may have common underlying genetic factors, there is also a likelihood that individuals sufferings from schizophrenia and depression tend to use marijuana because they feel the drug reduces the intensity of their symptoms. Nonetheless, the findings could help address marijuana and addiction and enable doctors to find a lasting treatment for the two conditions. At present, a comprehensive therapy to treat schizophrenia is yet to be found.
The findings of the study were published in the journal JAMA Psychiatry.