The authors administered 6 g of L-dopa to 8 schizophrenic patients and
750 mg of chlorpromazine to 7 schizophrenic patients. Chlorpromazine showed
only a modest advantage over L-dopa and only on some Brief Psychiatric
Rating Scale factor scores, and at maximum dosage the thought disturbance
factor score in the L-dopa-treated group was not worse than at baseline.
The results suggest that L-dopa is associated more with toxic than with
schizophreniform symptoms and that there is adaptation to its effects. The
authors discuss implications of these findings for the dopamine hypothesis