Reaching out towards cannabis: approach‐bias in heavy cannabis users predicts changes in cannabis use

Aims  Repeated drug exposure can lead to an approach‐bias, i.e. the relatively automatically triggered tendencies to approach rather that avoid drug‐related stimuli. Our main aim was to study this approach‐bias in heavy cannabis users with the newly developed cannabis Approach Avoidance Task (cannabis‐AAT) and to investigate the predictive relationship between an approach‐bias for cannabis‐related materials and levels of cannabis use, craving, and the course of cannabis use. Design, settings and participants  Cross‐sectional assessment and six‐month follow‐up in 32 heavy cannabis users and 39 non‐using controls. Measurements  Approach and avoidance action‐tendencies towards cannabis and neutral images were assessed with the cannabis AAT. During the AAT, participants pulled or pushed a joystick in response to image orientation. To generate additional sense of approach or avoidance, pulling the joystick increased picture size while pushing decreased it. Craving was measured pre‐ and post‐test with the multi‐factorial Marijuana Craving Questionnaire (MCQ). Cannabis use frequencies and levels of dependence were measured at baseline and after a six‐month follow‐up. Findings  Heavy cannabis users demonstrated an approach‐bias for cannabis images, as compared to controls. The approach‐bias predicted changes in cannabis use at six‐month follow‐up. The pre‐test MCQ emotionality and expectancy factor were associated negatively with the approach‐bias. No effects were found on levels of cannabis dependence. Conclusions  Heavy cannabis users with a strong approach‐bias for cannabis are more likely to increase their cannabis use. This approach‐bias could be used as a predictor of the course of cannabis use to identify individuals at risk from increasing cannabis use.