Introverts who tend to have fewer positive feelings, or to not be attracted to rewards in life, are more likely to abuse drugs than more extroverted people with positive emotions, a new study suggests.

Studying personality may help scientists better understand and treat substance use problems, according to the researchers from the National Institute on Drug Abuse. Researcher Dr. Sergi Ferré said people who are extroverted and have more positive emotions may be more open to rewards other than good feelings that come from using a drug. For instance, they may feel rewarded by certain social situations such as winning a game or receiving a promotion.

In contrast, people who are introverted and have fewer positive feelings may have less interest in these rewards, and instead be more influenced by pleasant sensations that come from using drugs.

The researchers found having a tendency to experience negative emotions, such as anxiety or depressed mood, is associated with substance use disorder. Having a difficult time stopping a behavior or action once it is started is also linked with an increased risk of substance abuse, The Huffington Post reports.

The researchers noted the likelihood a person will abuse drugs involves many factors, including genes, personality, environment and past drug use. The findings appear in the journal Trends in Cognitive Sciences.