Regular cannabis use is associated with cognitive impairments, including impaired decision making measured by the Iowa Gambling Task. The question remains whether the impulsivity measured in regular cannabis users may participate to impaired decision making. Interestingly, the Cambridge Gambling Task (CGT) is a computerized gambling task allows to differentiate risk taking and impulsivity when making a decision.

This study aims at separately exploring the impact of regular cannabis use on risk taking and impulsivity during decision making process.

To do so, we compared the performance of regular cannabis users and healthy controls during the CGT.

Forty-three regular cannabis users (> 7 units/week) with a cannabis use disorder (CUD), 8 non-CUD regular cannabis users and 30 healthy controls were recruited. Decision-making was assessed using the CGT. The following outcomes were considered: Delay aversion score, Overall proportion bet, quality of decision making, risk taking and risk adjustment.

The analysis on delay aversion score showed a group effect (F = 3.839, P = 0.026) but no effect on other CGT variables. This effect was explained by the fact that cannabis CUD users had a higher delay aversion score than healthy controls and non-CUD cannabis users.

In this study, CUD cannabis users had an increased impulsivity but no increase of risk taking and quality of decision-making. Future work should include the CGT with a clinical scale to evaluate impulsivity and a motor inhibition task to understand if the impairment observed relates to cognitive or motor abilities.

The authors have not supplied their declaration of competing interest.