L-tyrosine pharmacotherapy of schizophrenia: preliminary data.
The utility of L-tyrosine (10 g/day in four divided doses) as an adjuvant to molindone (150 mg/day) in the treatment of schizophrenia was investigated using a placebo-controlled, double-blind crossover design (3 weeks on L-tyrosine, 3 weeks on placebo). The objective of this inpatient study was to increase dopaminergic neural transmission along mesocortical projections in patients by increasing the precursor availability of L-tyrosine for dopamine biosynthesis. Theoretically, this approach might lessen both negative and positive symptoms of schizophrenia and improve frontal lobe-mediated neuropsychological performance. There was no evidence of statistically significant improvement conferred by L-tyrosine as measured by weekly Brief Psychiatric Rating Scale (BPRS), Schedule for the Assessment of Negative Symptoms (SANS), or Clinical Global Impressions (CGI) scales. The 12-h trough plasma level of L-tyrosine was significantly higher in all patients during the L-tyrosine phase of the study (t = -3.9, df = 20, p = 0.0009). At the end of each 3-week study period, no significant differences could be found in Wisconsin Card Sorting Test (WCST) or memory test performance. Smooth-pursuit eye movement (SPEM) performance had significantly more saccadic intrusions during the L-tyrosine supplementation phase compared to the placebo period. This increase in saccades during SPEM suggests that the tyrosine supplementation might have had some central effect.
Deutsch
S I
SI
Department of Veterans Affairs Medical Center, Psychiatry Service, Washington, DC 20422.
Rosse
R B
RB
Schwartz
B L
BL
Banay-Schwartz
M
M
McCarthy
M F
MF
Johri
S K
SK
D000328:Adult; D004192:Discrimination, Psychological / Q000187:drug effects; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects; D008972:Molindone / Q000627:therapeutic use; D011569:Psychiatric Status Rating Scales; D011698:Pursuit, Smooth / Q000187:drug effects; D012559:Schizophrenia / Q000188:drug therapy*; D012565:Schizophrenic Psychology; D014443:Tyrosine / Q000097:blood / Q000627:therapeutic use*
D014443:Tyrosine; D008972:Molindone