Problem in prolonged levodopa administration of Parkinson disease patients--from the standpoint of the autonomic...

We studied 50 patients with Parkinson's disease to determine any relation of epidemiologic factors (such as the duration of illness), the duration of levodopa therapy, the total amount of administered levodopa to degree of autonomic dysfunction. Autonomic dysfunction was evaluated using the composite autonomic scoring scale (CASS). The CASS scores were significantly higher among patients with greater administration amount of levodopa regardless of the duration of illness (p < 0.05). There was a definite positive correlation between cardiovascular heart rate index, which was one of the parameters of CASS and reflected parasympathetic neuron system function of cardiac origin, and the duration of levodopa therapy (r = 0.44, p < 0.01) or the total administered amount of levodopa (r = 0.43, p < 0.01). We conclude that long-term levodopa therapy negatively affects autonomic nervous function.