[Incidence, differential diagnosis, work capacity, mortality and cause of death in Parkinson disease]

Parkinson's disease is one of the most frequent neurological diseases, which affects about 1% of the population older than 65 years. After manifestation the clinical signs of Parkinson's disease chronically progress. According to the Hoehn and Yahr scale the severity of parkinsonian symptoms is graded into 5 stages. Interindividually there is a considerable range in the rate of progression, which is on average 0.4 per year on the Hoehn and Yahr scale. Intraindividually the progression of clinical symptoms is approximately linear. If the interval between two consecutive Hoehn and Yahr stages is known, the further rate of progression can be estimated by extrapolation. Correlated with the progression of disease is a diminution of earning capacity. As there is no cure, Parkinson's disease only terminates with the death of the patient accompanied by excess mortality and reduced life expectancy. Since the introduction of L-DOPA a significant reduction of excess mortality has already been achieved. For treated patients the mean time of survival is 13-14 years after the onset of clinical signs.