A longitudinal study of the effects of an L-dopa drug holiday on the course of Parkinson's disease.

Drug holidays as treatment in Parkinson's disease (PD) to ameliorate the effects of chronic L-dopa use are a controversial method. They are used in an attempt to resensitize dopamine receptors in the striatum so that L-dopa therapy can be reinstated at lower doses with fewer of the side effects that normally accompany long-term use of the drug. In the present study, 15 patients with PD were submitted to a 7-day L-dopa drug holiday and then followed for 3 years. The effect of the holiday on parkinsonian symptoms and grade of severity of PD was determined using the Webster and the Hoehn and Yahr scales, administered at intervals over the 3-year period. We found that within the first 6 months post-drug-holiday, there was a dramatic improvement in the rating of the symptoms of PD that was statistically significant (p < 0.005). At 12 months, Webster scale scores had risen, but they remained significantly improved (p < 0.05) in comparison with the first postholiday score. This level of improvement was maintained at 24 and 36 months. The grade of severity of the disease stabilized since Hoehn and Yahr scale scores improved for all patients, except one, for the length of the study. One patient left the study after 6 months for unknown reasons. Of the 14 patients that remained, three were given additional drug holidays: two patients at 12 months and one patient at 12, 24, and 36 months. All patients were able to be maintained on a reduced L-dopa dose regimen of 50-70% of their pre-drug-holiday level for the entire 3-year period. In the patients in whom the drug holiday was least beneficial overall, there was a notable reduction in rigidity and in the "on-off" phenomenon. We conclude that an L-dopa drug holiday is a valuable option in the treatment of PD.