Reduced serum dopamine-beta-hydroxylase activity in paranoid schizophrenics.

The serum dopamine-beta-hydroxylase activity of 134 carefully selected paranoid schizophrenic patients was compared with that of 118 normal controls. Significantly reduced serum DBH activity found in the schizophrenic group in comparison to the control group could not be brought into relationship with the patients' age, nor with neuroleptic treatment. Manic depressive patients showed values similar to the normal control group. It is discussed that mainly genetically determined low serum DBH activity may be related to the hyperdopaminergic pathomechanism of paranoid schizophrenia.