Background: Previous research has yielded conflicting results regarding the long term consequences of cannabis use on cognitive functioning. Although in the cannabis literature, there is a commonly held belief associated with cannabis use called, “amotivational syndrome” the authors were unable to find any studies of neuropsychological performance that attempted to manipulate motivation.
Methods: Fifty-five undergraduates (34 cannabis users and 21 non-users) participated in an extensive neuropsychological battery. The experimenter read a statement at the beginning of the battery designed to induce motivation. Group differences on test performance were calculated with a one-way analysis of variance (ANOVA) for tests that did not differ in gender, and a 2 x 2 ANOVA (user by gender) for tests that did differ in gender.
Results: Significant group differences were found on four measures in the battery. Rey Complex Figure (RCF) Copy yielded a significant negative effect for cannabis use. California Verbal Learning Test-II (CVLT-II) Short Delay Free Recall, CVLT-II Short Delay Forced Choice, and CVLT-II Long Delay Cued Recall yielded significant positive effect for cannabis use in males. The groups did not significantly differ (p >.05) on any other tests in the battery.