Objective: As the perceived risk of cannabis use continues to decline among youths and access continues to increase, it becomes more important to synthesize the rapidly growing literature on the effects of cannabis on neurocognition. Hundreds of studies examining associations between cannabis use and neurocognitive functioning have been published in recent decades. However, results often differ across individual studies, particularly when sample sizes are small. Metaanalytic methods help to make sense of this literature and have been increasingly applied to studies on cannabis use and neurocognition.Methods: A systematic literature search using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted to identify peer-reviewed metaanalyses of neurocognitive or functional neuroimaging data that examined associations between cannabis use and non-acute effects on neurocognitive functioning (n = 8).Results: Current findings suggest that regular healthy cannabis users, regardless of age, display poorer neurocognitive functioning relative to nonusers of small to medium effect sizes across many neurocognitive domains, as well as functional brain alterations when compared to non-users. Adverse effects are not uniform across neurocognitive domains and evidence for adolescent-onset users having poorer neurocognitive outcomes remains equivocal based on these studies. However, less is known about cannabis effects on neurocognition among clinical samples, as findings from specific clinical samples revealed mixed results.Conclusions: Meta-analyses have played an important role in helping to grasp the totality of results from a large body of literature on cannabis effects on neurocognition, yet more research (particularly large-scale longitudinal studies) is needed to identify critical periods or patterns of use that are more likely to result in negative outcomes.

Background and aims Although poor decision‐making (DM) has been correlated with problematic cannabis use (CU), cross‐sectional designs make it difficult to determine whether poor DM represents an antecedent and/or consequence of CU. The current study measured bidirectional associations between CU and DM among adolescents over 2 years and compared these findings to those observed with episodic memory, which is consistently reported as a consequence of CU. We also measured the role of DM as a risk factor for cannabis use disorder (CUD) onset. Design Two‐year longitudinal study with five bi‐annual assessments. Participants Participants were 401 adolescents aged 14–17 years at baseline. Setting Miami, Florida, USA. Measurements CU frequency and CUDs were assessed at each time‐point through the Drug Use History Questionnaire and Structured Clinical Interview for DSM‐IV, respectively. Neurocognition was assessed at odd time‐points throughout the Iowa Gambling Task, Game of Dice Task and Cups Task [decision‐making (DM)] and the Wechsler Memory Scale IV and California Verbal Learning Test II (episodic memory). We used latent growth curve modeling to examine bidirectional influences between CU and neurocognition over time. We applied discrete time survival analyses to determine whether baseline DM predicted CUD onset. Findings Greater lifetime CU frequency was associated with poorer episodic memory at baseline (bs = −14.84, −16.44, Ps = 0.038, 0.021). Greater CU escalation predicted lesser gains in immediate episodic memory (b = −0.05, P = 0.020). Baseline DM did not predict CU escalation (b = 0.07, P = 0.421), nor did escalation in CU predict changes in DM (b = 0.02, P = 0.352). Baseline DM also did not predict CUD onset (adjusted OR = 1.01, 95% confidence interval = 0.98–1.06). Conclusions This study replicates findings that poorer episodic memory in adolescents appears to be a consequence of cannabis use, even among adolescents at earlier stages of use. Poor decision‐making does not appear to be either a consequence of or a risk factor for escalating cannabis use or onset of cannabis use disorder among adolescents.