Differences in heart rate among recent marijuana use groups.

BACKGROUND Marijuana use increases cardiac sympathetic activity within minutes of its use and this effect may begin to decrease as soon as one hour after marijuana use. However, the cardiovascular effects of marijuana use more than an hour after use is poorly characterized. The purpose of the current study is to compare heart rate, a marker of cardiac sympathetic activity, across recent marijuana use groups (never used=63; recent use [in the past 24 hours; subacute] = 13; in the past 7 days, but not in the past 24 hours = 17). Overall, the current sample included 93 African American/Black college students, with a mean age of 20.03 (SD = 2.21). METHODS Participants completed a demographic form, a brief battery of psychological questionnaires, and had their heart rate assessed at baseline. RESULTS Analysis of covariance showed that heart rate was statistically significantly lower in the recent use group (M = 62.38) compared with the non-users group (M = 73.92). This difference persisted before and after statistically adjusting for demographic covariates. CONCLUSIONS These results suggest that there may be a cardiovascular process that occurs when using marijuana that results in a compensatory, reduced heart rate.