Predicting beneficial response to a protein-redistribution diet in fluctuating Parkinson's disease.

To identify factors that might help in predicting the benefit to be gained from a protein-redistribution diet (PRD) we subjected 26 parkinsonian patients with motor fluctuations refractory to optimal timing and dosage of levodopa plus bromocriptine to a 2,000-2,500 Kcal., 65-80 g/d protein containing diet maintained for 8-12 weeks. Fifteen patients were eligible for evaluation, 10 of whom being benefited by the PRD (79 percent reduction in the mean "off" time in "on-off" charts). When the duration and pattern of the fluctuations were compared in the 10 diet-benefit patients with those in 5 diet-failure patients only dose-failures consistently occurring postprandially were resolved by the PRD. Wearing-off failures responded unpredictably while random "on-off" fluctuations were present only in the diet-failure group. Nocturnal akinesia and peak-dose dyskinesias often worsened. In no patient "on"-time quality was modified by the diet. In addition, the diet-failure group was characterized by a younger mean age at onset (p less than 0.05) and by longer duration in their fluctuations (p less than 0.001). Though requiring confirmation in a larger series, our results suggest that parkinsonian patients showing fluctuations over prolonged periods, particularly those having a pattern of random "on-off" oscillations in motor performance and dose-failures unrelated to meals are unlikely to benefit from a PRD.