Dihydropteridine reductase in schizophrenic patients

The activity of the enzyme dihydropteridine reductase (DHPR) has been recently found to be one of the factors controlling the rate of synthesis of dopamine, norepinephrine, and serotonin, thought to be involved in the etiology of schizophrenia. Several lines of evidence suggest that peripheral and brain DHPR enzymes may be identical. In addition, peripheral DHPR activity has been hypothesized to be important in determining the level of phenylethylamine, a putative psychotogen that is produced peripherally and crosses the blood-brain barrier. Since DHPR activity has never been investigated in schizophrenic patients, we measured the whole blood activity in 20 schizophrenic patients and 20 matched controls. There was no difference between the groups in DHPR activity.