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Loss of long-duration response to levodopa over time in PD: implications for wearing-off. OBJECTIVE: To determine the modifications of the long-duration response to levodopa in PD over a 1-year period. BACKGROUND: The development of predictable motor fluctuations in PD has been attributed mainly to modifications over time of the short-duration response to levodopa, whereas the role of the long-duration response has not been widely investigated. METHODS: In 17 patients with PD the authors examined prospectively both the short-duration response and the long-duration response to levodopa under standardized conditions on two different occasions separated by a period of approximately 1 year (11.7 +/- 3.6 months). RESULTS: At the end of the follow-up period, the short-duration response increased in magnitude but did not change significantly in duration. A total of 24% of patients lost the long-duration response 1 year after their first examination, but a sustained long-duration response could be reestablished by shortening the interdose interval for levodopa intake. Moreover, the duration of the long-duration response after discontinuation of treatment became significantly shorter during 1 year. CONCLUSION: Modifications of the long-duration response may have a pivotal role in generating a fluctuating response, and suggest that therapeutic strategies based on maintenance of the long-duration response should be sought to avoid the appearance of motor fluctuations. Neurology 1999 Mar 10;52(4):763-7 Zappia M, Oliveri RL, Montesanti R, Rizzo M, Bosco D, Plastino M, Crescibene L, Bastone L, Aguglia U, Gambardella A, Quattrone A Institute of Neurology, University of Catanzaro, Italy. PMID: 10078724, UI: 99176610 http://www.ncbi.nlm.nih.gov/PubMed/ janet paterson 52 now / 41 dx / 37 onset PO Box 171 Almonte Ontario K0A 1A0 Canada a new voice <http://www.geocities.com/SoHo/Village/6263/> [log in to unmask]