CSF and plasma vasopressin concentrations in dementia.

In 16 patients with primary degenerative dementia mean CSF vasopressin concentration was lower (0.9 +/- 0.1 pg/ml (mean +/- SEM)) than in 28 control patients (1.3 +/- 0.1 (mean +/- SEM)) (p less than 0.01). In 18 patients with normal pressure hydrocephalus and potentially reversible dementia mean CSF vasopressin concentration (1.2 pg/ml +/- 0.1 (mean +/- SEM)) was not different from that found in controls. Several of the demented patients had inappropriate plasma vasopressin concentrations suggesting a defect in osmoregulation. These findings encourage further clinical trials of vasopressin in patients with primary degenerative dementia, but it is emphasised that the low CSF vasopressin concentration in these patients might be only a nonspecific phenomenon due to the diffuse loss of cells within the central nervous system.