A genetic variant discovered by researchers from the Danish psychiatric project iPSYCH affects how much of a specific nicotine receptor is formed. People who have less of this receptor in the brain are at greater risk of becoming cannabis abusers.
Associate Professor Ditte Demontis from Aarhus University, who led the study, used a nationwide Danish cohort to analyze the complete genome of more than 2,000 cannabis abusers and the genome of 50,000 control subjects. The researchers subsequently repeated these findings in an analysis of an additional 5,500 cannabis abusers and more than 300,000 control subjects.
The team also included genetic data from studies in which researchers examined the underlying genetics for cognition such as the ability to complete an education. In this case they found that people with a higher number of genetic variants associated with impaired cognition also have an increased risk of cannabis abuse.
The study is a major step forward in understanding the particular biological mechanisms that lie behind the abuse of cannabis.