Complications of disease and therapy: a comparison of younger and older patients with Parkinson's disease.

The incidence of complications associated with disease and treatment was compared in younger versus elderly patients with Parkinson's disease (PD). One hundred sixty-five patient records were divided according to patient age into two groups ("younger," 41 to 64, and "elderly," > or = 65 years) and reviewed for the incidence of dyskinesias, fluctuations, freezing, psychosis, dementia, depression, and insomnia. Younger patients had a greater incidence of chorea (75.8 percent vs 49.5 percent), dystonia (82.3 percent vs 49.0 percent), fluctuations (90.1 percent vs 68.1 percent), depression (73.2 percent vs 36.8 percent), and insomnia (57.9 percent vs 18.1 percent). There were no significant differences in the incidence of freezing, dementia, or psychosis. At the time of the first adverse event, there was no difference in patient characteristics such as gender, lag time from disease diagnosis to levodopa initiation, disease symptoms at the time of diagnosis, levodopa dose, or concomitant drug use despite the fact that the older group had a longer duration of disease, higher Hoehn and Yahr stage, an older age at onset of PD, and longer duration of levodopa use. Younger patients with PD experience a greater incidence of adverse effects than do elderly PD patients. The spectrum of adverse effects is comparable to those of young-onset (< or = 40 years) patients.