Effectiveness of Cannabinoids for Treatment of Dementia: A Systematic Review of Randomized Controlled Trials

Objective: In the last decade, research has focused on developing novel medications for the treatment of dementia. Cannabinoids are one of the potential agents under investigation. The present study aimed to examine the evidence concerning the effectiveness of cannabinoids for the treatment of dementia. Methods: We undertook a systematic review complying to PRISMA guidelines. Four databases were searched including Medline, Embase, Cochrane Library, and PsychINFO. Results: Five studies evaluated the use of cannabinoids for anorexia and agitation in dementia. One study used dronabinol 5 mg/day to target anorexic symptoms of dementia which positively impacted on weight. Results of two trials investigating the effectiveness of tetrahydrocannabinol (THC) 1.5-4.5 mg/day for the treatment of agitation indicated no significant differences between THC and placebo. The most recent trial reported significant improvement in agitation using nabilone at 1-2 mg/day. However, levels of evidence of these agents were rated as low and very low because of low sample size and methodology issues. No studies were available that investigated the use of cannabinoids to moderate cognitive symptoms in dementia. Conclusions: Findings from a few robust randomized controlled trials suggest that nabilone might be useful for the treatment of agitation in patients with dementia, but there is no convincing evidence for THC. Additional studies are needed to further clarify and assess the benefits of these treatments. Clinical Implications: There were no randomized controlled trials investigating the use of cannabinoids for the treatment of cognitive decline in dementia. Studies on THC reported no significant improvement in agitation. It may be too early to postulate that cannabinoids have any effect on dementia symptoms or their progression.