What does research show about cannabis for Huntington's disease?

Huntington's disease (HD) is a neurodegenerative disorder caused by CAG repeat expansion in the HTT gene, leading to progressive striatal and cortical neurodegeneration. The ECS connection is particularly strong: CB1 receptor loss in the striatum is one of the earliest and most consistent findings in HD — preceding symptom onset by years and correlating with disease progression. This makes CB1 receptor loss both a potential biomarker and therapeutic target. Preclinical evidence: cannabinoids (particularly CBD and CBG) showed neuroprotective effects in HD mouse models, reducing striatal neurodegeneration and improving motor function. Clinical evidence: a 2016 RCT (López-Sendón Moreno et al., n=26) found Sativex (nabiximols) did not significantly improve motor function vs. placebo over 12 weeks — the primary endpoint was not met. However, secondary outcomes (total motor score, neuropsychiatric symptoms) showed trends toward improvement. A 2023 observational study found cannabis users with HD reported improved mood and sleep. The disconnect between strong preclinical rationale and modest clinical results is a recurring theme in HD research broadly.