Effects of L-dopa and vitamin B6 on electroencephalograms of schizophrenic patients: a preliminary report.

1. To assess the therapeutic effect of low-dose L-Dopa therapy and associated EEG changes in chronic schizophrenia, 10 patients with a mean duration of illness of 12.4 years were treated with L-Dopa for a period of eight weeks during which the dosage was increased progressively from an initial level of 300 mg q.d. biweekly up to 600 mg q.d. The treatment was moderately effective in one case and slightly efficacious in one, produced no significant change in the conditions of seven patients while the remaining patient showed exacerbation; hence a noticeably low rate of improvement. There occurred no significant changes in the EEG pattern in the series of 10 patients on the average. The individual patients' responses, nevertheless, could be classified into three groups: one with no observable EEG changes, the second showing a slight degree of increase in alpha activity and the third exhibiting diminution of alpha activity in the EEG. The patients in the latter two groups all had durations of disease less than 10 years. 2. Observations were made primarily of changes in the EEG in 20 chronically schizophrenic patients with a mean duration of disease of 13 years receiving 60 mg of vitamin B6 (as pyridoxal-5'-phosphate) daily over a period of four weeks. Slight increase of alpha activity and decrease of theta activity in the EEG were noted on the average of the 20 cases, in response to the vitamin B6 therapy. The increase of alpha activity was frequently seen among patients with a duration of illness less than 10 years whose pretreatment EEG pattern had been alpha dominant (five out of 10 cases), whereas a slight ameliorative tendency of EEG was observed only in one out of 10 patients whose pretreatment EEG pattern had been slow-wave dominant. Symptomatic improvement was evident only in one of the 20 cases studied. 3. Observations were made of the therapeutic effect and associated EEG changes in eight patients receiving combined medication of 200 mg L-Dopa and 30 mg vitamin B6 (as pyridoxal-5'-phosphate) daily for a period of 12 weeks. Of these eight patients with a mean duration of disease of 18.3 years, two showed excellent response, three good and three fair; hence good to excellent responses attained in five out of the eight cases or 62.5%. A marked increase in alpha activity in the EEG occurred from the 2nd to 4th weeks onward in all eight cases. The EEG changes were likely to precede the symptomatic improvement. 4. To sum up the results of these three clinical trials, administration of L-Dopa alone resulted in practically no symptomatic improvement or EEG changes in patients with chronic schizophrenia whilst vitamin B6 administered singly as pyridoxal-5'-phosphate scarcely produced significant symptomatic improvement but brought about a slight ameliorative tendency in the EEG of such patients. Both symptomatic amelioration and EEG improvement occurred following combined medication of L-Dopa and vitamin B6...