Parkinson's disease.

The prevalence of Parkinson's disease rises with age. The clinical features can be the typical ones or those associated with the "late-onset" type, with more gait and balance problems and a mild progressive dementia. Other disorders, such as stroke and essential tremor, may be mistaken for Parkinson's disease, or multiple conditions may be present which modify the response to treatment. The treatment of choice is a low dose of one of the L-dopa-decarboxylase inhibitor drugs. Other agents have a high incidence of side effects, particularly confusion, which also occurs with L-dopa in higher doses.