Depressed baroreflex sensitivity in patients with Alzheimer's and Parkinson's disease.

Parkinson's disease (PD) and Alzheimer's dementia (AD) are often associated with an autonomic neuropathy. The extent of autonomic involvement, however is poorly defined and unpredictable. In order to assess the autonomic cardiovascular regulation baroreflex sensitivity (BRS) was determined non-invasively in 23 patients (age: 65 +/- 9.3 years) with PD and 24 patients with AD (age: 72.3 +/- 7.2 years). The results were compared with those on 22 healthy age- and sex-matched volunteers. Patients with PD and AD exhibited marked abnormalities in cardiovascular autonomic reflex regulation showed by markedly depressed BRS. The possible predictive value of centrally based depression of baroreflex sensitivity necessitates further studies.