The impact of methamphetamine use and dependence: A systematic review on the cognitive-behavioural implications for road safety

Abstract

Methamphetamine (MA) users are over-represented in vehicle crash statistics but under-represented in the road safety research literature. This systematic review evaluates the current research base relating to MA use and its associated cognitive-behavioural outcomes; and aims to discuss the implications that these findings may have towards driving and future road safety research directions. Following PRISMA guidelines, a literature search was conducted on research studies using six different databases. Inclusion criteria were acute and chronic MA use in humans, with outcome variables relating to cognitive performance, behavioural tendencies, or psychopathology. Primary exclusion criteria included outcomes that were not directly translatable to road safety outcomes (e.g., health) or very specific samples that may have confounded the effects of MA use (e.g., prisoners). In total, 101 publications met the criteria for inclusion in the review. The literature showed that firstly, acute use (but not abuse) of MA may lead to cognitive enhancements, although these findings are not likely translatable to real-world use. Secondly, evidence suggested that chronic MA use is associated with cognitive impairments, self-regulatory difficulties, and increased aggression, suggesting that MA users may be at a significantly increased risk on the road, in a variety of domains. In addition, chronic MA use has been linked to a range of psychological issues (e.g., psychosis; anxiety; depression), which may exacerbate the negative cognitive-behavioural effects of MA. Finally, abstinence from MA was shown to reduce the aversive impacts of chronic MA use, although cognitive improvements have been demonstrated to take much longer, compared to behavioural and psychopathology conditions. The limitations associated with the current MA literature base were evaluated and methodological suggestions were made for future research to better understand the effect of MA use patterns on driving performance and behaviour.