Cannabis use is frequent in PD, despite limited data regarding its effects. 

Between 09/2018 and 04/2020, 51 persons enrolled, and 41 (66% men) took study drug: mean age 69.2 (SD 7.4), H&Y 2.6 (0.6). Mean final dose was 2.3 (0.4) mg/kg/day, i.e., 189 (55) mg CBD and 6.3 (1.8) mg THC, and participants were on study drug for 17.3 (7.0) days.

Unblinded study staff assigned participant data to two groups according to treatment randomization, which were matched in age, sex and H&Y. Group A (n=22), reported AEs 206 times, and 19 (86%) reported an AE: dizziness (56%); fatigue, feeling of relaxation, headache, decreased concentration, (36%); feeling abnormal, feeling drunk, nausea, somnolence (27%); confusion, (23%); dry mouth, fall, increased appetite (18%); agitation, disorientation, increased concentration, thinking abnormal, weakness (14%). Group B (n=19) reported AEs 93 times, and 17 (89%) reported an AE: headache (37%); somnolence (28%); feeling of relaxation (21%); cold, cough, diarrhea, fatigue, insomnia, nausea, (16%); anorexia, decreased concentration, depression, dizziness, elevated mood, feeling drunk (11%). Most AEs were mild; in Group A they occurred more at 1.25 mg/kg/day, in Group B at 2.5 mg/kg/day. Two serious AEs occurred in Group A, none in Group B. No significant changes in physical exam, safety labs and EKG occurred. One participant withdrew due to intolerance.