Bourque Josiane, Potvin Stéphane
Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
Department of Psychiatry and Addiction, Faculty of Medicine, University of Montreal, Montreal, QC, Canada.
Front Psychiatry. 2021 Jun 10;12:596601. doi: 10.3389/fpsyt.2021.596601. eCollection 2021.
In recent years, several jurisdictions have revised their regulation policy toward both medical and recreational use of cannabis. These changes have elicited concerns regarding how legalization impacts academic achievement and work performance. This review evaluates the acute and long-term (residual) association between cannabis use and cognitive functioning that underlies poor academic and work performance. Relative to other reviews, this article focuses on cross-over randomized controlled trials and prospective designs given that they allow to test the impairing effects of cannabis exposure at the within-subject level. Acute cannabis cognitive effects are discussed separately for known confounding factors such as levels of delta-9-tetrahydrocannabinol (Δ-THC), Δ-THC:cannabidiol ratio, previous cannabis use and, comorbidity with psychosis-spectrum disorders. The cognitive residual effects of cannabis are detailed in relation to duration of abstinence, frequency of use, comorbidity with psychosis-spectrum disorders, types of cognitive domains assessed, and age of cannabis use initiation. Moreover, considering the fact that adequate longitudinal studies can make inferences about causality between cannabis use and impaired cognitive functioning when disentangling between-subject from within-subject variation, proofs for the three main non-mutually exclusive hypotheses about this relationship will be presented: i) the cognitive vulnerability hypothesis as part of the more general common antecedent hypothesis, ii) the concurrent cannabis impairing hypothesis, and iii) the neurotoxic hypothesis of cannabis. Current research provides evidence for mild to moderate acute cannabis effects on episodic and working memory, processing speed, and executive functions. Mild residual impairing effects were also observed in these exact same cognitive domains, suggesting that adverse effects following cannabis intoxication persist at least days or weeks following cannabis abstinence. Relative to adult-onset, adolescent-onset cannabis use seems to explain the dose-response relationship and is associated with longer lasting residual effects even in mild users (<weekly). The association between cannabis and cognition is likely explained by common antecedents, such that genetic and shared environment factors predispose individuals to both cannabis use and cognitive deficits, and to a lesser degree, neurotoxic effects.
近年来，一些司法管辖区已修订其对大麻医疗和娱乐用途的监管政策。这些变化引发了人们对合法化如何影响学业成绩和工作表现的担忧。本综述评估了大麻使用与认知功能之间的急性和长期（残留）关联，而认知功能是学业和工作表现不佳的基础。与其他综述相比，本文侧重于交叉随机对照试验和前瞻性设计，因为它们能够在个体内部层面测试大麻暴露的损害作用。对于已知的混杂因素，如Δ-9-四氢大麻酚（Δ-THC）水平、Δ-THC与大麻二酚的比例、既往大麻使用情况以及与精神病谱系障碍的共病情况，将分别讨论急性大麻对认知的影响。大麻的认知残留效应将根据戒断持续时间、使用频率、与精神病谱系障碍的共病情况、所评估的认知领域类型以及开始使用大麻的年龄进行详细阐述。此外，考虑到充分的纵向研究在区分个体间差异和个体内差异时能够对大麻使用与认知功能受损之间的因果关系进行推断，将提出关于这种关系的三个主要且并非相互排斥的假设的证据：i）作为更一般的共同先因假设一部分的认知易感性假设，ii）并发大麻损害假设，以及iii）大麻的神经毒性假设。当前研究为大麻对情景记忆和工作记忆、处理速度及执行功能产生轻度至中度的急性影响提供了证据。在这些完全相同的认知领域也观察到了轻度的残留损害效应，这表明大麻中毒后的不良影响在戒断大麻后至少持续数天或数周。相对于成年后开始使用大麻，青少年期开始使用大麻似乎可以解释剂量反应关系，并且即使在轻度使用者（<每周使用）中也与持续时间更长的残留效应相关。大麻与认知之间的关联可能由共同先因来解释，即遗传和共享环境因素使个体既易于使用大麻又易于出现认知缺陷，并且在较小程度上还存在神经毒性作用。
