A systematic review of the effects of cannabis on cognition in people with multiple sclerosis

Bessenyei, Kitti; Leitner, Damian; Yakovenko, Igor; Fisk, John D.; Prentice, Jennifer L.

doi:10.1016/j.msard.2021.103338

Cited by 7 publications

(7 citation statements)

References 52 publications

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“…In agreement with the systematic review by Landrigan et al [7], our results indicate that the impact of CBMs on cognitive functioning is minimal as long as the doses of THC are low to moderate. Unfortunately, the studies are too divergent to specify the maximum dose of THC tolerated before cognition is negatively affected.…”

Section: Discussionsupporting

confidence: 92%

“…It is important to differentiate between intoxication or withdrawal from prolonged abuse and controlled medical treatment without or with limited psychoactive effects. The former has been extensively studied and is known to affect cognitive functions, as also mentioned in the recent review by Landrigan et al [ 7 ] whereas the latter has not been studied as extensively and thus is the subject of this review. Basically, we want to know if we can treat patients with CBM without negatively affecting, or affecting to a minimal degree, their cognitive functions and hence their daily activities.…”

Section: Discussionmentioning

confidence: 99%

“…Importantly, the most common reported adverse event was ‘cognitive or attention disturbances’ with an odds ratio of 5.67 (95% CI 2.72–11.79) compared to placebo. While the findings by Stockings et al [ 6 ] rely on self-reported cognitive disturbances a recent systematic review by Landrigan et al [ 7 ] has assessed the effects of cannabis on cognition in people with multiple sclerosis by synthesising studies using a valid objective measure of cognitive functioning. Landrigan et al [ 7 ] concludes that studies of oral cannabis-based medicinal preparations such as Sativex in general do not affect cognitive functioning compared to controls/placebo treatments.…”

Section: Introductionmentioning

confidence: 99%

“…While the findings by Stockings et al [ 6 ] rely on self-reported cognitive disturbances a recent systematic review by Landrigan et al [ 7 ] has assessed the effects of cannabis on cognition in people with multiple sclerosis by synthesising studies using a valid objective measure of cognitive functioning. Landrigan et al [ 7 ] concludes that studies of oral cannabis-based medicinal preparations such as Sativex in general do not affect cognitive functioning compared to controls/placebo treatments. However, studies of whole-plant cannabis were more often associated with negative effects on cognitive functions.…”

Section: Introductionmentioning

confidence: 99%

“…It should be noted that the negative impact on cognition was based on self-reports and not recognised neuropsychological tests. Only, Landrigan et al [ 7 ] has assessed the impact on cognitive functioning by synthesising studies using valid cognitive tests, however only in patients with MS.…”

Section: Introductionmentioning

confidence: 99%

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The effect of medical cannabis on cognitive functions: a systematic review

2022

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Background 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. Methods 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. Findings 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. Conclusions 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.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%