The relevance of clinical subtypes for disease course, family history and epidemiological variables in Parkinson's disease.

Clinical outcome and relevance of genetic and epidemiological factors were evaluated in 161 patients with idiopathic Parkinson's disease (PD) with regard to onset symptoms [tremor (T) vs non-tremor (NT)], to clinical classification into tremor-dominant (TD), alkineto-rigid (AR), and equivalent (EQ) subtypes, and to disease onset before the 45th year of age (EO) and after age 69 (LO). Patients were investigated by questionnaire-based personal interview and clinical examination. Allegedly symptomatic first-degree relatives were examined personally or had sufficient medical documentation to allow neurological diagnosis. Disease course was more favorable in T than in NT, in TD than in AR or EQ, and in EO compared with LO. Among EO and LO patients, clinical subtypes TD, AR and EQ were not differently distributed. Frequency of first-degree relatives with PD or essential tremor and any epidemiological variable tested were not elicited differently between TD, AR and EQ patients, with the exception that TD reported more frequent premorbid travelling. EO patients reported higher frequencies of premorbid head trauma and rural living than LO patients. The more favorable disease prognosis of patients with predominant tremor at presentation and of patients with early disease onset is corroborated. Clinical subgroups do not differ in genetic and epidemiological factors.