Effects of cannabis on cognitive function in patients with multiple sclerosis

Honarmand, Kimia; Tierney, Mary C.; O’Connor, Paul; Feinstein, Anthony

doi:10.1212/wnl.0b013e318212ab0c

Cited by 82 publications

(46 citation statements)

References 352 publications

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“…Similarly, frontal activation appeared more prominently in the cannabis group across tasks (see figure 2). 3 Furthermore, we have shown that more extensive working memory problems in the cannabis group were associated with a different pattern of cerebral activation observed on fMRI. Significantly, no structural differences, be they lesion volume, global atrophy, or DTI metrics, were discernible between the groups, a finding that overlaps with results from numerous cannabis imaging studies in healthy subjects (see Martin-Santos et al 17 for a review).…”

Section: E14mentioning

confidence: 85%

“…findings of greater cognitive problems in patients with MS who smoke cannabis 2,3 and in keeping with what we know of cognition-MRI correlates from the MS literature in general, 5 we hypothesized that these deficits would be associated with the following: (1) greater cerebral atrophy; (2) more subtle indices of brain pathology derived from diffusion tensor imaging (DTI); and (3) a more dysfunctional pattern of cerebral activation during an fMRIbased working memory task, namely the N-Back. Our choice of the latter as a marker of working memory was based on the fact that there is an available N-Back fMRI literature in subjects with MS, [6][7][8] albeit small, and a much larger one in healthy controls.…”

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confidence: 99%

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Effects of cannabis on cognition in patients with MS

et al. 2014

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Objective: To determine functional and structural neuroimaging correlates of cognitive dysfunction associated with cannabis use in multiple sclerosis (MS). Methods:In a cross-sectional study, 20 subjects with MS who smoked cannabis and 19 noncannabis users with MS, matched on demographic and neurologic variables, underwent fMRI while completing a test of working memory, the N-Back. Resting-state fMRI and structural MRI data (lesion and normal-appearing brain tissue volumes, diffusion tensor imaging metrics) were also collected. Neuropsychological data pertaining to verbal (Selective Reminding Test Revised) and visual (10/36 Spatial Recall Test) memory, information processing speed (Paced Auditory Serial Addition Test [2-and 3-second versions] and Symbol Digit Modalities Test), and attention (Word List Generation) were obtained. Results:The cannabis group performed more poorly on the more demanding of the Paced Auditory Serial Addition Test tasks (i.e., 2-second version) (p , 0.02) and the 10/36 Spatial Recall Test (p , 0.03). Cannabis users had more diffuse cerebral activation across all N-Back trials and made more errors on the 2-Back task (p , 0.006), during which they displayed increased activation relative to nonusers in parietal (p , 0.007) and anterior cingulate (p , 0.001) regions implicated in working memory. No group differences in resting-state networks or structural MRI variables were found. Conclusions:Patients with MS who smoke cannabis are more cognitively impaired than nonusers.Cannabis further compromises cerebral compensatory mechanisms, already faulty in MS. These imaging data boost the construct validity of the neuropsychological findings and act as a cautionary note to cannabis users and prescribers. Cognitive dysfunction affects 40% to 60% of patients with multiple sclerosis (MS).1 Data suggest that patients with MS who smoke cannabis have more extensive cognitive difficulties than those who do not. In particular, problems with working memory, 2 information processing speed, and executive dysfunction 3 appear to be exacerbated by the use of cannabis. Given that cognitive deficits in patients with MS are known to adversely affect the ability to sustain employment, maintain relationships, continue recreational pursuits, and attend to activities of daily living, 4 a better understanding of how smoking cannabis may impair brain function in MS is needed.To date, there have been no imaging-cognition studies of patients with MS who smoke cannabis. This contrasts with an extensive MRI literature of patients with MS in general in which cognitive deficits have been linked to numerous structural and functional brain metrics.

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Section: E14mentioning

confidence: 85%

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Effects of cannabis on cognition in patients with MS

et al. 2014

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“…Thus, it is possible that the QST parameters do not reflect the varied central psychotropic effects of cannabis. Additionally, the possibility that cannabis might cause cognitive dysfunction, as shown in patients with other neurological diseases (Ghaffar and Feinstein, 2008; Honarmand et al, 2011), should also be considered. Therefore, the benefits of its use should be weighed against its potential harm.…”

Section: Discussionmentioning

confidence: 99%

Effect of medical cannabis on thermal quantitative measurements of pain in patients with Parkinson's disease

Shohet

Khlebtovsky

Roizen

et al. 2016

European Journal of Pain

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Background: Cannabis can alleviate pain of various etiologies. This study assessed the effect of cannabis on motor symptoms and pain parameters in patients with Parkinson's disease (PD). Methods: Twenty patients with PD who were licensed to use cannabis underwent evaluation before and 30 min after cannabis consumption and again after long-term use. Motor function was assessed with the Unified PD Rating scale (UPDRS) by two raters, one blinded. Pain was assessed with the Pain Rating Index (PRI) and Visual Analogue Scale (VAS) of the short-form McGill Pain Questionnaire. Thermal quantitative sensory testing (QST) was performed in 18 patients. The two consecutive QST measurements were validated in 12 cannabis-na€ ıve patients with PD. Results: There was a significant decrease from baseline to 30 min after cannabis consumption in mean motor UPDRS score (38.1 AE 18 to 30.4 AE 15.6, p < 0.0001), total PRI (27 AE 13.5 to 9.7 AE 11, p = 0.001), and VAS score (6.4 AE 2.8 to 3.6 AE 3.1, p = 0.0005). Mean cold pain threshold decreased significantly in the more affected limb, but only after exclusion of two patients who consumed cannabis by vaporizer rather than smoking (19.5 AE 5.2 to 15.6 AE 8.7°C, p = 0.02). After longterm (median 14 weeks) exposure, mean heat pain threshold decreased significantly in the more affected limb in all treated patients (43.6 AE 3.5 to 40.9 AE 3.3°C, p = 0.05) and in cannabis smokers (43.7 AE 3.6 to 40.3 AE 2.5°C, p = 0.008). Conclusions: Cannabis improved motor scores and pain symptoms in PD patients, together with a dissociate effect on heat and cold pain thresholds. Peripheral and central pathways are probably modulated by cannabis. Significance: Quantitative sensory test results are significantly altered following cannabis consumption in patients with PD. Cannabis probably acts on pain in PD via peripheral and central pathways.

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“…Re cently, concerns have been cited regarding the potential long-term cognitive effects of cannabis use in patients with multiple sclerosis. 26,27 Although these studies have had small samples and other limitations, 28,29 the issue warrants further attention.…”

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Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial

Corey–Bloom

Wolfson

Gamst

et al. 2012

CMAJ

170

141

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Research CMAJBackground: Spasticity is a common and poorly controlled symptom of multiple sclerosis. Our objective was to determine the short-term effect of smoked cannabis on this symptom. Methods:We conducted a placebo-controlled, crossover trial involving adult patients with multiple sclerosis and spasticity. We re cruited participants from a regional clinic or by referral from specialists. We randomly assigned participants to either the intervention (smoked cannabis, once daily for three days) or control (identical placebo cigarettes, once daily for three days). Each participant was assessed daily before and after treatment. After a washout interval of 11 days, participants crossed over to the op posite group. Our primary outcome was change in spasticity as measured by patient score on the modified Ashworth scale. Our secondary outcomes included patients' perception of pain (as measured using a visual analogue scale), a timed walk and changes in cognitive function (as measured by patient performance on the Paced Auditory Serial Addition Test), in addition to ratings of fatigue.Results: Thirty-seven participants were randomized at the start of the study, 30 of whom completed the trial. Treatment with smoked cannabis resulted in a reduction in patient scores on the modified Ashworth scale by an average of 2.74 points more than placebo (p < 0.0001). In addition, treatment reduced pain scores on a visual analogue scale by an average of 5.28 points more than placebo (p = 0.008). Scores for the timed walk did not differ significantly between treatment and placebo (p = 0.2). Scores on the Paced Auditory Serial Addition Test decreased by 8.67 points more with treatment than with placebo (p = 0.003). No serious adverse events occurred during the trial. Interpretation:Smoked cannabis was superior to placebo in symptom and pain reduction in participants with treatment-resistant spasticity. Future studies should examine whether different doses can result in similar beneficial effects with less cognitive impact. Abstract

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Effects of cannabis on cognitive function in patients with multiple sclerosis

Cited by 82 publications

References 352 publications

Effects of cannabis on cognition in patients with MS

Effects of cannabis on cognition in patients with MS

Effect of medical cannabis on thermal quantitative measurements of pain in patients with Parkinson's disease

Smoked cannabis for spasticity in multiple sclerosis: a randomized, placebo-controlled trial

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