The effects of recreational drug use on prospective memory

Recreational drug use is thought to harm the neurotransmitter communication systems that are important for cognitive processes. This study aimed to investigate the effects of recreational drug use on prospective memory (PM), using multiple research methods. The study consists of three interrelated studies. In the first study, 27 studies were systematically reviewed. The studies were divided into two broad categories based on testing methods used: self-report and lab-based testing methods. The quality of the included studies was assessed across five categories: sample type, sample size, abstinence period, testing methods, and control for confounding factors. The overall quality of evidence was good for six studies, moderate for sixteen studies, and low for five studies. Self-report studies showed inconsistent results, while lab-based methods consistently found that illegal drug users performed worse than non-users on various PM tests. In the second study, 53 drug users and 47 non-users were recruited and examined on PM, using questionnaire- and lab-based measures. The results revealed that drug users displayed PM deficits, but only in the lab-based measure. In the third study, seven drug users were interviewed on different components of PM (e.g., executive functions, attention) to understand how they manage to remember and execute delayed intentions in everyday life from their point of view to unfold the observed discrepancy between the questionnaire- and lab-based PM measures in the first and second studies. It was evident that retrospective memory, cues availability at retrieval, time awareness, and attention play a crucial role in PM, thus impairments in such domains might be associated with poor PM performance in drug users. The study also uncovered the cognitive factors (i.e., metacognition and motivation) that explain the observed discrepancy. In summary, this comprehensive investigation underscores the consistent PM impairments identified through lab-based measures. The study also sheds light on critical cognitive factors and their role in understanding the observed differences between questionnaire- and lab-based PM measures.