Addicts’ Vulnerability to Drugs Linked to Family Ties in Study

The brains of addicts and their healthy siblings are different than those of unrelated, healthy volunteers, a study has found, suggesting vulnerability to drug dependency may be partly inherited.

The aberrations were found in brain scans on 150 subjects. They exist in areas thought to govern self-control and habit-formation, the researchers said. Having a family member with an addiction raised the odds of becoming dependent about eightfold, said Karen Ersche, a researcher at the University of Cambridge in the U.K. and the study’s lead author.

The results, reported today in the journal Science, may spur new testing to determine who is most at risk to develop addiction, said Nora Volkow, director of the National Institute on Drug Abuse in Bethesda, Maryland, who wrote an editorial accompanying the paper. The next thing to study might be why one sibling became addicted and another didn’t.

“We have the means now to develop a potential biomarker for determining poor self-control,” Volkow, who wasn’t involved in the research, said in a telephone interview today. “That could, for example, be used to identify those at greater risk and develop prevention.”

The brain scans show the addicted subjects and their siblings had less white matter tracts near the right inferior frontal cortex, a region known to be involved in self control, Ersche said. The siblings also showed more tissue volume in areas such as the putamen and amygdala that are associated with habit formation.

Determining Why

That makes sense, since most people who try drugs don’t get addicted, Ersche said. “Cocaine is a highly addictive drug but not everyone who uses it gets dependent. Only about 20 percent of people who use cocaine get dependent,” she said.

The data may also suggest that strategies for increasing self-control may help those at risk for addiction.

“What I have noticed is that siblings who don’t get addicted had other goals,” Ersche said. “They’d tried cannabis or ecstasy, but had other things they wanted to pursue, like education or sport. We need to follow up to see whether that’s significant.”

The study was funded by the U.K.’s Medical Research Council.