A single oral dose of cannabidiol did not reduce upper limb tremor in patients with essential tremor

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Abstract
Essential tremor (ET) is a common clinical syndrome characterized by action tremors affecting both upper limbs that can compromise manual tasks’ execution and impair functional and social performance. The primary pharmacological treatment is symptomatic, but effective medicines are somewhat limited. There is a clear need to find new effective therapies for the treatment of ET. Cannabidiol (CBD) is a modulator of CB1 receptor and CB1 agonists can reduce tremors in experimental models. We hypothesized that a single acute CBD intake would reduce tremors in ET patients. We performed a randomized, controlled, double-blind, crossover study on 19 patients with ET. They were 10 males and 9 females, had mean 63 years of age, and mean 23 years of disease duration and had insufficient control of their tremors with the usual pharmacological treatment. They ingested a single oral dose of CBD (300 mg) or placebo in two experimental sessions performed 2-weeks apart. Patients were evaluated immediately before and after oral ingestion (60 min and 210 min), using the Fahn-Tolosa-Marin clinical scale. There was no carryover effect. There were no significant differences in upper limb tremors score, specific motor task tremor scores (writing and drawing/pouring) or clinical impression of change after treatment with placebo or CBD. In conclusion, a single 300 mg oral dose of CBD had no significant effect on the severity of upper limb tremors of ET patients. Our findings did not exclude the possibility that chronic treatment with CBD could have a symptomatic effect.