Abstract
Fluctuations in performance in patients with Parkinson's disease on chronic levodopa therapy (the "on-off" effect) are due to several factors. The increasing severity during treatment of early morning akinesia, "freezing" episodes, and end-of-dose deterioration are probably due to progression of the underlying disease. Peak-dose dyskinesia and peak-dose akinesia are due to levodopa over dosage. "Yo-yo-ing", which is the severest form of such fluctuation in mobility and dyskinesias, may represent the sum of these disorders.
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