Cannabidiol and cognitive functions/inflammatory markers in Parkinson's disease: A double-blind randomized controlled trial at Buriram Hospital (CBD-PD-BRH trial)

Introduction: Cannabidiol (CBD) may alleviate Parkinson's disease (PD) symptoms, but its cognitive and antiinflammatory effects remain unclear due to limited randomized trials. This study evaluates CBD's efficacy in PD patients. Methods: Sixty PD patients were randomized into CBD (n = 30) or placebo (n = 30) groups. The CBD group received a sublingual CBD-enriched product (101.9 mg/ml CBD, 4.8 mg/ml tetrahydrocannabinol [THC]). The primary outcome was improvement in the Montreal Cognitive Assessment (MoCA) delayed recall scores. Secondary outcome measures included other MoCA components, the total MoCA score, motor examination, anxiety/ depression, inflammatory markers, renal/liver function, and adverse events. CBD and THC levels were measured at 12 weeks. Results: Nine patients were lost to follow-up, leaving 51 participants (CBD: 27; placebo: 24) for analysis. The mean CBD dose was 26 mg/day, and THC was 1.2 mg/day. CBD was detected in 17 patients (mean: 2 ng/ml), with no THC found. Delayed recall scores showed no group differences. The CBD group improved naming scores (mean difference: 0.37, 95 % CI: 0.01 to 0.73). Language scores increased in the placebo group but remained unchanged in the CBD group. Inflammatory markers and other outcomes showed no differences, except for elevated alkaline phosphatase in the CBD group, with no serious side effects in either group. Conclusions: In this 12-week trial, 26 mg/day of sublingual CBD was safe, with no adverse effects on motor, cognitive, or affective symptoms in PD patients, and improved MoCA naming scores. Future studies should investigate higher doses and use targeted naming tests.