Coming off cannabis: a cognitive and functional MRI study in people with multiple sclerosis (pwMS)
ECTRIMS Online Library. Feinstein A. 09/11/19; 278902; P542
Anthony Feinstein
Anthony Feinstein

Abstract: P542

Type: Poster Sessions

Abstract Category: Pathology and pathogenesis of MS - MRI and PET

A. Feinstein1, C. Meza1, C. Stefan2, W.R. Staines3

1Psychiatry, University of Toronto, Sunnybrook Research Institute, 2Clinical Laboratory and Diagnostic Services, Centre for Addiction and Mental Health, Toronto, 3Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada

Background: Smoking cannabis may add to cognitive deficits in pwMS. It is unclear whether abstinence can lead to a reversal in these deficits.
Objectives: 1. To determine whether 28 days of cannabis abstinence in cognitively impaired pwMS can lead to cognitive improvement. 2. To ascertain the functional brain changes associated with improved information processing speed in pwMS off cannabis.
Methods: Forty cognitively impaired pwMS who had started smoking cannabis after the onset of their disease and who had used it for at least 4 days a week over many years were divided by odd-even number selection into cannabis continuation (CC) and withdrawal (CW) groups. Assessments at baseline and day 28 included urine analysis of cannabis metabolites, serial versions of the Brief Repeatable Neuropsychological Battery (BRNB) and fMRI while completing a modified SDMT task.
Results: The two groups were well matched demographically and neurologically at baseline. There were no baseline between group cognitive differences, but by day 28 the CW group (who by then had minimal cannabis-THC metabolites in their urine), performed significantly better on every BRNB index (p < .0001 for all). At baseline the two groups had similar performance on the fMRI-compatible SDMT and there were no between group differences in brain activation. By day 28, the CW group completed more trials correctly (p < .012) with a faster reaction time (p < .002) and this was associated with significantly increased activation in brain regions known to underpin performance (bilateral inferior frontal gyri, caudate, cerebellum, p < .001 for all). Coming off cannabis led to a mild increase in insomnia in two pwMS.
Conclusions: Cognitively impaired pwMS who are long-term heavy cannabis users can show significant improvement in processing speed, memory and executive function once off cannabis for at least 28 days. Improvements on the SDMT are matched by patterns of brain activation aligned with that seen in cannabis naïve pwMS and healthy drug free people.
Disclosure: Disclosure: This study was funded by the Multiple Sclerosis Society of Canada
Cecilia Meza: nothing to disclose
Cristiana Stefan: nothing to disclose
W. Richard Staines: nothing to disclose
Anthony Feinstein: Speaker's honoraria from Biogen Idec, Sanofi-Genzyme, Merck-Serono, book royalties from Cambridge University Press, consultancy fees from Akili Interactive.

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