(HealthDay News) – Caffeine has a limited effect on excessive daytime somnolence in patients with Parkinson’s disease (PD), but is associated with an improvement in objective motor measures.

Ronald B. Postuma, MD, of McGill University and Montreal General Hospital, and colleagues conducted a six-week randomized controlled trial involving 61 PD patients with daytime somnolence who received either 100mg caffeine twice daily for three weeks, then 200mg twice daily for three weeks (30 patients), or matching placebo (31 patients). Daytime somnolence was measured using the Epworth Sleepiness Scale score.

The researchers observed a nonsignificant reduction in the Epworth Sleepiness Scale score for patients randomized to caffeine, using a primary intent-to-treat analysis, and significant improvements on the Clinical Global Impression of Change and on the Epworth Sleepiness Scale score, on per-protocol analysis. Caffeine-treated patients experienced a reduction in the total Unified Parkinson’s Disease Rating Scale score and on the objective motor component. No change was noted in quality of life, depression, or sleep quality, but there was modest improvement in global health measures.

“Caffeine provided only equivocal borderline improvement in excessive somnolence in PD, but improved objective motor measures,” the authors write. “These potential motor benefits suggest that a larger long-term trial of caffeine is warranted.”

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