Certain Genes Amplify Impact of Drugs on Brain

People with a specific genetic makeup experience greater loss of brain function when dependent on drugs, HealthDay reported March 8.

Researchers at Brookhaven National Laboratory used MRI scans and genotyping to study 40 men addicted to cocaine and compared them with 42 men who were not substance-dependent. They found that cocaine users with a specific genotype had fewer neurons in areas of the brain related to self-control, learning, memory, and decision-making.

In addition, they found that long-term concurrent use of alcohol contributed to further losses of gray matter. According to the study abstract, this was “likely to further impair executive function and learning in cocaine addiction.” Stopping substance use might stop such losses, the researchers said.

“This research shows that genes can influence the severity of addiction,” said Nelly Alia-Klein, Ph.D., who co-authored the study. “The results suggest that addicted individuals with low MAOA [monoamine oxidase A] genotype may need a different kind of treatment than other addicted individuals who carry the high MAOA genotype.”

According to Klein, it would be premature to change treatment approaches yet. “Only males were part of this study, and therefore it is important for future studies to examine these genetic and brain effects in females as well,” she said. “Also, further studies will have to be done to track these gene-brain behavior patterns throughout a life span that influence the volume of the brain's neurons.”

The study, titled “Gene x Disease Interaction on Orbitofrontal Gray Matter in Cocaine Addiction,” appeared in the March 2011 issue of the Archives of General Psychiatry.