Caffeine consumption has no significant impact on motor skills in patients with Parkinson’s disease, based on data from a double-blind, randomized, placebo-controlled trial of 121 adults. The findings were published online Sept. 27 in Neurology.
Data from previous studies have suggested a link between caffeine consumption and reduced risk of Parkinson’s disease, wrote Ronald B. Postuma, MD, of McGill University in Montreal, and his colleagues ( Neurology. 2017 Sep 27. doi: 10.1212/WNL.0000000000004568 ). In addition, Dr. Postuma and his coauthors found a small impact of caffeine on motor skills in patients with existing Parkinson’s as a secondary outcome in a 2012 study on the role of caffeine on daytime sleepiness. Based on these findings, they designed a multicenter, randomized, controlled trial of 121 adults with Parkinson’s to assess the impact of caffeine. The average age of the patients was 62 years and the average disease duration was 4 years.
In this study, 60 patients received 200 mg of caffeine in capsule form twice daily, in the morning and after lunch for 6 months; 61 received a placebo. The amount of caffeine was approximately equal to three cups of coffee.
Motor skills worsened in the caffeine group by an average of 0.16 points on the Movement Disorder Society–sponsored Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part III during patients’ “on” state and by 0.64 points in the placebo group; the difference was not significant.
The researchers found no differences between groups in the clinical global impression of change based on both patient and examiner assessment. In addition, no differences appeared in depression or anxiety, or in quality of life.
The study findings included long-term follow up data from 88 patients assessed at 12 months and 66 patients assessed at 18 months. The results were similar to the 6-month results, and the study was stopped, although the original design included a 4-year extension.
A total of 29 patients in the caffeine group and 31 patients in the placebo group reported adverse events, and 7 patients in the caffeine group and 5 in the placebo group discontinued the study because of side effects. A serious adverse event was reported by one patient in each group, but neither was deemed related to the interventions.
The findings contrast with the effects of caffeine in the 6-week study in 2012 that showed a significant, 3.2-point improvement in motor skills on the MDS-UPDRS part III with caffeine use, as well as reduced daytime sleepiness, the researchers said ( Neurology. 2012;79:651-8 ). Interpretations of the different findings between the trials may be constrained by factors including differences in the study populations, speed of dose escalation, and trial duration and the possible short-term nature of caffeine’s impact, they noted. “Regardless, our core finding is that caffeine cannot be recommended as symptomatic therapy for parkinsonism.” However, “since caffeine is safe and generally well tolerated, it seems reasonable to empirically try intermittent moderate doses of caffeine for somnolence, and repeat if improvement is seen,” they added.
Dr. Postuma disclosed grant funding from the Canadian Institute of Health Research, the Webster Foundation, and Fonds de Recherche du Québec-Santé for this study.