The Institute of Medical Sciences (IMS), University of Toronto, Toronto, ON, Canada.
Addictions Division, Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada.
Neuropsychopharmacology. 2017 Oct;42(11):2259-2271. doi: 10.1038/npp.2017.85. Epub 2017 Apr 26.
Cross-sectional studies of the effects of cannabis on cognition in schizophrenia have produced mixed results. Heavy and persistent cannabis use in schizophrenia is a common clinical problem, and effects of controlled abstinence from cannabis in these patients have not been carefully evaluated. The present study sought to determine the effects of cannabis abstinence on cognition in patients with schizophrenia and co-occurring cannabis dependence. We utilized a 28-day cannabis abstinence paradigm to investigate the state-dependent effects of cannabis on select cognitive outcomes in cannabis-dependent patients with schizophrenia and non-psychiatric controls. Nineteen patients and 20 non-psychiatric male cannabis-dependent participants underwent 28 days of cannabis abstinence. Cognition was assessed on day 0, 14, and 28 using a comprehensive neuropsychological battery. Clinical symptoms were assessed weekly. Abstinence was facilitated by contingency reinforcement confirmed by twice weekly urinalysis. Forty-two percent of patients and 55% of controls achieved end-point abstinence (p=0.53), which was biochemically-verified (day 28 urinary THC-COOH <20 ng/ml). In this preliminary study, schizophrenia-abstainers demonstrated improvements in Hopkins Verbal Learning Test-Revised (HVLT-R) performance over time [F(2,14)=4.73, p<0.03] (d=1.07). Lesser improvements on HVLT-R were observed in non-psychiatric control abstainers (d=0.66), and with abstinence on other cognitive test measures, in both patients and controls. Verbal memory and learning may improve in schizophrenia and control subjects with cannabis abstinence, but larger more definitive studies are needed. Our findings underscore the importance of developing effective interventions for cannabis use disorders in schizophrenia.
横断面研究表明，大麻对精神分裂症认知的影响结果不一。精神分裂症患者中重度且持续的大麻使用是一个常见的临床问题，但尚未仔细评估这些患者中对大麻的受控戒断的影响。本研究旨在确定大麻戒断对精神分裂症合并大麻依赖患者认知的影响。我们采用 28 天的大麻戒断范式，研究大麻依赖的精神分裂症患者和非精神病对照者中，大麻的状态依赖性对特定认知结果的影响。19 名患者和 20 名非精神病男性大麻依赖参与者接受了 28 天的大麻戒断。在第 0、14 和 28 天使用综合神经心理学测试对认知进行评估。每周评估临床症状。通过每周两次的尿液分析确认的条件强化来促进戒断。42%的患者和 55%的对照组达到了终点戒断（p=0.53），这是通过生物化学验证的（第 28 天尿液 THC-COOH <20ng/ml）。在这项初步研究中，精神分裂症戒断者在霍普金斯言语学习测试修订版（HVLT-R）上的表现随着时间的推移有所提高[F(2,14)=4.73，p<0.03]（d=1.07）。非精神病对照组的戒断者（d=0.66）HVLT-R 的改善较小，患者和对照组的其他认知测试指标的戒断也是如此。言语记忆和学习可能会在精神分裂症和对照组的大麻戒断中得到改善，但需要进行更大、更明确的研究。我们的研究结果强调了在精神分裂症中开发有效的大麻使用障碍干预措施的重要性。
