The authors measured copper levels in the cerebrospinal fluid of 8 schizophrenic subjects and 6 controls. The schizophrenic subjects had significantly lower CSF copper values than the controls, which is consistent with the hypothesis that there is reduced central activity of copper-dependent enzymes in schizophrenia. These enzymes, tyrosine hydroxylase and dopamine-beta-hydroxylase, are involved in the synthesis and catabolism of dopamine.