New research from the Danish psychiatric project, iPSYCH, shows that a specific gene is associated with an increased risk of cannabis abuse. The gene is the source of the so-called nicotine receptor in the brain, and people with low amounts of this receptor have an increased risk of cannabis abuse.
Cannabis is the most commonly used illegal drug in Denmark and the world, and about one in ten users become addicted to the drug. Researchers at iPSYCH have discovered a gene that they associate with cannabis abuse.
We found that the disorder was associated with a genetic variant. This variant affects how much of a nicotine receptor is formed in the brain. "
Associate Professor Ditte Demontis of the University of Aarhus, who is behind the study
The genetic variant discovered by researchers affects how much of a particular nicotine receptor is formed. People who have less of this receptor in the brain are at greater risk of becoming cannabis abusers.
Ditte Demontis and his colleagues used a Danish national cohort to analyze the complete genome of more than 2,000 marijuana users and the genome of 50,000 controls. The researchers subsequently replicated these findings in an analysis of more than 5,500 marijuana users and more than 300,000 control subjects.
The researchers also included genetic data from studies in which researchers examined the underlying genetics for cognition, such as eg. the ability to complete an education.
Here, they found that people with a greater number of genetic variants associated with impaired cognition also have an increased risk of cannabis abuse.
"People who abuse marijuana often do worse in the education system, and our results show that this can be partially explained by genetics. This means that people with a problem of abuse have more genetic variations in the genome that increase the risk of abuse of marijuana ". , while at the same time negatively affecting their ability to get an education, "explains Ditte Demontis.
The study is the first of its kind on this scale and represents a step towards understanding the particular biological mechanisms behind cannabis abuse.
"We need to do even more research on how genetic differences in the genome contribute to the development of cannabis abuse, and we need to map the precise biological mechanisms that lead to a person at greater risk of becoming a drug user than another." Our hope is to be able to improve treatment and, perhaps, in the long run, to avoid such abuse, "says Ditte Demontis.
Demontis, D. et al. (2019) The study of broad genomic association implies CHRNA2 in the disorder of cannabis use. Neuroscience of nature. doi.org/10.1038/s41593-019-0416-1.