Study links genetics to cannabis dependence in adolescent females

A study conducted on mice by a team of researchers have identified important implications for understanding the influence of genetics on cannabis dependence in adolescent females.

The brain's endocannabinoid system regulates the activity of cannabinoids that are normally produced by the body to influence brain development and regulate mood, as well as those from external sources, such as the psychoactive ingredient THC, also known as D9-tetrahydrocannabinol, which is found in cannabis.

An enzyme called fatty acid amide hydrolase (FAAH) breaks down a cannabinoid called anandamide that is naturally found in the brain and is most closely related to THC, helping to remove it from circulation.

In the study which was published in Science Advances, the researchers examined mice harbouring a human gene variant that causes FAAH to degrade more easily, increasing overall anandamide levels in the brain.

From the preclinical research by Weill Cornell Medicine investigators, they discovered that the variant resulted in an overactive reward circuit in female--but not male adolescent mice--that resulted in a higher preference for THC in females.

Dr. Caitlin Burgdorf, recent doctoral graduate from the Weill Cornell Graduate School of Medical Sciences, and the lead author said: "Our study shows that a variant in the FAAH gene, which is found in about one-third of people, increases vulnerability to THC in females and has large-scale impact on brain regions and pathways responsible for processing reward."

"Our findings suggest that genetics can be a contributing factor for increased susceptibility to cannabis dependence in select populations," Caitlin added.

The result showcased that female mouse with the FAAH variant showed an increased preference for the environment in which they'd been exposed to THC over a neutral environment when they were exposed to the substance during adolescence, and the effect persisted into adulthood.