Dopamine-beta-hydroxylase activities in serum and cerebrospinal fluid of aged and demented patients.

Age-related changes in dopamine-beta-hydroxylase (DBH) activities in serum and cerebrospinal fluid (CSF) were determined. In normal subjects, serum DBH activity increased gradually from the 3rd to the 8th decade, but decreased prominently in the 9th decade. DBH activity in CSF did not differ between younger and older subjects. Serum DBH activity decreased significantly in senile dementia of Alzheimer's type (SDAT, 12.2 +/- 8.8 nmoles/min/ml, P less than 0.05), but not in multi-infarct dementia (MID, 13.9 +/- 9.1 nmoles/min/ml) compared to control subjects (17.1 +/- 9.5 nmoles/min/ml). The decrease of serum DBH in SDAT was more prominent in patients with severe dementia and/or severe brain atrophy. DBH activity in CSF was much lower than that in serum and did not correlate with each other. DBH activity in CSF obtained from SDAT patients (1.60 +/- 0.94 nmoles/h/ml) and from MID patients 2.01 +/- 0.99 nmoles/h/ml) were both lower than that from other neurological diseases without dementia (4.04 +/- 3.81 nmoles/h/ml). DBH in CSF from SDAT patients was significantly lower (P less than 0.05) than that from controls, but that from MID did not differ from controls. Noradrenergic nervous dysfunction is partly associated with pathophysiology and life expectancy of senile dementia of Alzheimer's type (SDAT).