The present study examined whether recreational use of cannabis affected prospective memory ability in teenagers and young adults.

An independent measures design utilising pre-existing groups of cannabis users and non-users was employed in which an opportunity sample of 90 undergraduates studying at universities in the north east of England completed an objective video-based prospective memory task and a series of self-report questionnaires assessing failures in prospective memory, levels of anxiety and depression, use of strategies to assist remembering and recreational drug use.

Analysis of covariance (ANCOVA) revealed no significant differences in the number of self-reported failures in prospective memory. Cannabis users, however, correctly recalled significantly fewer location-action combinations during the video-based prospective memory task than non-users. These findings were observed after controlling for age, level of anxiety and depression, use of strategies to assist remembering, and the use of other recreational drugs including alcohol, nicotine and ecstasy.

The findings from the objective prospective memory task in the present study suggest that recreational cannabis use has a detrimental effect on prospective memory ability in teenagers and young adults.