Comparison of midday serum dopamine-β-hydroxylase activity in depressed patients and normal controls

Serum dopamine-β-hydroxylase (DBH) activity has previously been reported to have a mid-afternoon peak in normal subjects and to have more frequent but smaller variations in depressed patients. We failed to observe any mid-afternoon peak in DBH activity in 9 normal subjects or 6 psychotically depressed patients. There was a smaller coefficient of variation of mean serum DBH activity in the depresed patients than the normal controls. Serum DBH activity was also significantly lower in the psychotically depressed patients than the normal controls.