Old-onset Parkinson's disease compared with young-onset disease: clinical differences and similarities.

Of 261 patients with clinically diagnosed Parkinson's disease (PD), whose age at the onset was 58.2 +/- 11.3, 46 patients with the onset age above 70 (the mean for the whole group + 1SD) were compared to 44 patients with onset age below 47 (the mean for the whole group - 1 SD). Old-onset PD patient were more susceptible to develop psychotic complications of levodopa treatment. More often had they tremor both as presenting and dominant symptom of their disease. Among young-onset PD bradykinesia was more often the dominant clinical feature, and susceptibility to levodopa induced dyskinesia was higher. In 9 cases of young-onset PD (20.5% of this group) paraesthesia was a presenting symptom, compared to only 1 patient (2%) in the group of old-onset PD.