Department of Psychology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
Danish Hospital for Rheumatic Diseases, University Hospital of Southern Denmark, Sonderborg, Denmark.
Syst Rev. 2022 Oct 3;11(1):210. doi: 10.1186/s13643-022-02073-5.
Cannabis-based medicines are widely used in the treatment of a number of medical conditions. Unfortunately, cognitive disturbances are often reported as adverse events, although conversely, cognitive improvements have been reported. Hence, the objective of the present study was to identify, critically appraise and synthesise research findings on the potential impact of cannabis-based medicines on cognitive functioning.
Four databases (EMBASE, PsycINFO, PubMed and Scopus) were systematically searched. Studies were included if they provided findings on the impact of cannabis-based medicines in controlled settings on cognitive functioning measured by recognised cognitive tests in human adults. Study participants were required to be their own case-control, and neither studies on abuse, abstinences, patients with severe neurodegenerative diseases nor cancer-related pain conditions were included. Screening, risk of bias assessment and data extraction were conducted independently by two researchers. Findings were tabulated and synthesised by outcome.
Twenty-three studies were included, comprising a total of N = 917. Eight studies used Sativex as the cannabis-based medicine two used Epidiolex, two other studies used sprays, three studies used gelatine capsules, five smoked cannabis, two other and finally one studied cannabis withdrawal. Fifteen studies reported non-significant findings; six reported cognitive impairments; one study found cognitive improvement and a single study found improvement following withdrawal. Thirteen studies had cognitive or neuropsychological functioning as the primary outcome.
Due to a large heterogeneity and methodological limitations across studies, it is not possible to make any definite conclusions about the impact of cannabis-based medicines on cognitive functioning. However, the majority of high-quality evidence points in the direction that the negative impact of cannabis-based medicines on cognitive functioning is minor, provided that the doses of THC are low to moderate. On the other hand, long-term use of cannabis based medicines may still adversely affect cognitive functioning. In the studies that found impaired cognitive functioning to be significant, all of the test scores were either within the normal range or below what would be characterised as a neuropsychologically cognitive impairment.
基于大麻的药物被广泛用于治疗多种医疗条件。不幸的是，经常报告认知障碍作为不良事件，尽管相反，也有报道称认知改善。因此，本研究的目的是确定、批判性评价和综合研究结果，以确定基于大麻的药物对认知功能的潜在影响。
系统地搜索了四个数据库（EMBASE、PsycINFO、PubMed 和 Scopus）。如果研究提供了在受控环境下基于大麻的药物对认知功能的影响的发现，这些研究通过人类成年人的公认认知测试进行测量，则纳入研究。研究参与者必须是他们自己的病例对照，并且不包括滥用、禁欲、患有严重神经退行性疾病或癌症相关疼痛状况的患者的研究。筛选、偏倚风险评估和数据提取由两名研究人员独立进行。研究结果按结果进行制表和综合。
纳入了 23 项研究，共包括 N = 917 人。八项研究使用 Sativex 作为基于大麻的药物，两项研究使用 Epidiolex，两项研究使用喷雾剂，三项研究使用凝胶胶囊，五人吸食大麻，两项研究使用其他方法，最后一项研究研究了大麻戒断。十五项研究报告无显著发现；六项研究报告认知障碍；一项研究发现认知改善，一项研究发现戒断后改善。十三项研究将认知或神经心理学功能作为主要结果。
由于研究之间存在很大的异质性和方法学限制，因此无法就基于大麻的药物对认知功能的影响得出任何明确的结论。然而，大多数高质量证据表明，基于大麻的药物对认知功能的负面影响较小，前提是 THC 剂量低至中等。另一方面，长期使用基于大麻的药物仍可能对认知功能产生不利影响。在发现认知功能受损具有显著意义的研究中，所有测试分数都在正常范围内或低于被认为是神经认知功能障碍的范围。
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