The psychological effects of cannabis in MS: impact on cognition, pain, mood and fatigue [abstract]

There is increasing interest in the therapeutic potential of cannabinoids in multiple sclerosis (MS), but also reservations about their effects on psychological variables, which are largely unexplored. Studies of community samples of cannabis users indicate fairly subtle cognitive changes, even after many years of significant use. However, there are suggestions that cannabinoids may have greater effects in vulnerable groups. The research question addressed by this substudy of the cannabis (CAMS) trial was: do cannabinoids in an MS population affect memory and attention, fatigue, pain or mood? A subset of patients was recruited from the 660 patients in the MRC-funded CAMS study, a double-blind randomized controlled trial of cannabinoids for spasticity in MS. Patients received either THC, natural cannabis oil with equivalent THC, or placebo (all via capsules containing oil), for thirteen weeks. Eighty-nine patients from the two largest centers completed a psychological battery before, during and after the medication period. The battery assessed cognition, focusing on memory and attention (California Verbal Learning Test, Paced Auditory Serial Addition Task, Digit Span, Digit Symbol, and the self report Dysexecutive Questionnaire); fatigue (Fatigue Impact Scale); pain (McGill Pain Questionnaire 78 adjectives); and mood (Chicago Multiscale Depression Inventory, Hospital Anxiety and Depression Scale). There were also visual analogue scaled for cognition, fatigue, pain and mood to help validate the standardized measures in a cannabinoid-medicated MS population. Initial findings from preliminary statistical analysis will be given and their likely impact on potential use of cannabis in MS will be discussed.