Some marijuana users develop problems associated with use of the drug — neglecting important work responsibilities or family relationships — while others do not. Researchers have reported associations that suggest potential links among certain measures of impulsive personality, variants in certain genes, and greater likelihood of problems among marijuana users. In a study this month in the Journal of Studies on Alcohol and Drugs, Cinnamon Bidwell, assistant professor (research) of psychiatry and human behavior, and co-authors measured these potential predictors in combination in 151 young adult marijuana users. What they found was that the highest likelihood of marijuana-related problems arose in people who scored high on a standardized questionnaire of “trait-level” impulsivity (a long-standing impulsive personality characteristic but not necessarily more transient impulsive behavior) and who had a particular variation of the gene CNR1. “Our findings support a role for trait impulsivity and endocannabinoid system genes in predicting risk for marijuana-related problems among regular users,” wrote the authors, many of whom are affiliated with Brown's Center for Alcohol and Addiction Studies.