CLINICAL AND PHARMACOLOGICAL DIFFERENCES IN EARLY-ONSET VERSUS LATE-ONSET PARKINSONS-DISEASE

We evaluated whether patients with early-onset Parkinson's disease (EO PD) have a different clinical profile and pharmacological response tha n those with late-onset disease (LOPD). We performed a retrospective a nalysis and an acute pharmacological challenge with L-Dopa in 34 EOPD (age at onset between 21 and 40 years) and 34 LOPD (onset after age 60 ) patients. All patients completed a structured questionnaire cross-ch ecked against medical record charts and underwent an acute levodopa te st. Most significant differences were in the mode of onset, time to di agnosis, and degree of initial improvement. We did not observe differe nces with regard to motor fluctuations. The acute levodopa test showed no differences in latency to response onset between groups. However, the magnitude of the response was greater and the duration shorter in EOPD patients. Younger patients had greater reductions in bradykinesia scores, whereas posture/gait symptomatology was less responsive in ol der patients. The type and severity of dyskinesias also differed signi ficantly between groups. Our findings suggest that central pharmacokin etics, pharmacodynamics, and, possibly, nondopaminergic systems play a role in the age-related differences observed in Parkinson's disease.