The risk of psychosis associated with cannabis use by people with attention-deficit hyperactivity disorder: A systematic review

BackgroundGiven that both attention-deficit hyperactivity disorder (ADHD) and cannabis use are known independent risk factors for psychosis, people with ADHD who consume cannabis may be especially vulnerable. The main objective of the current study was to explore the links between ADHD, cannabis use and psychosis outcomes.MethodsA systematic review was conducted to examine the risk of psychosis among people with ADHD who are exposed to cannabis. Literature searches were conducted using four electronic bibliographic databases. The findings were synthesised following the synthesis without meta-analysis reporting guideline.ResultsThree studies meeting the inclusion criteria were identified. These studies were heterogeneous in design, and the assessment of the risk of bias found one study to be fair quality and two to be good quality. Two included studies indirectly suggested that cannabis use does not impact the risk of psychosis among people with ADHD, and one study supported cannabis having a similar impact on the risk of psychosis for people with and without ADHD.ConclusionThere have been very few studies examining the relationship between ADHD, cannabis use, and psychosis. Currently, there is very little evidence to suggest that the risk of psychosis associated with cannabis use is heightened for people diagnosed with ADHD. However, limitations in existing evidence highlight the need for further research on this topic.