Somatostatin-like immunoreactivity in the cerebrospinal fluid of patients with Parkinson's disease and its relation to dementia.

Acetylcholinesterase, somatostatin-like immunoreactivity, and homovanillic acid levels were measured in the cerebrospinal fluid of 36 patients with early stages of Parkinson's disease and in 19 control patients. In patients with Parkinson's disease the levels of somatostatin-like immunoreactivity were lower than in the controls (p less than 0.01); these values were lowest in the demented Parkinsonian patients. Concentrations of homovanillic acid were also significantly lower in Parkinsonian patients (p less than 0.05). In contrast, no changes were observed in the acetylcholinesterase activity of patients with Parkinson's disease. The reduced somatostatin-like immunoreactivity in CSF agrees with previous post-mortem studies and indicates that Parkinson's disease and Alzheimer's disease may have some neurochemical features in common.