A meta-analysis of the response to chronic L-dopa in patients with schizophrenia: therapeutic and heuristic implications.
BACKGROUND
While it is generally believed that administration of the dopamine precursor levodopa ( L-dopa) exacerbates symptoms of schizophrenia, numerous reports suggest that adjunctive L-dopa may be beneficial. This body of literature has not been critically reviewed.


OBJECTIVE
On the basis of published studies, to determine whether L-dopa administered concomitantly with antipsychotic drugs provides a beneficial response in patients with schizophrenia.


METHODS
This review examined 30 studies involving 716 patients. Due to wide methodological variability and limited statistical information, only five studies encompassing 160 patients could be included in a meta-analysis. The others were evaluated qualitatively.


RESULTS
When L-dopa was added to antipsychotic drugs, the overall improvement was moderate ( d=0.71) and highly significant ( P<0.0001). There were 16 other studies in which L-dopa was added to antipsychotic drugs, but which did not meet criteria for inclusion in the meta-analysis. In these, worsening occurred in less than 20% of patients; the percentage of improved patients varied widely but had a central tendency around 50%.


CONCLUSIONS
. In patients already on antipsychotic drugs, the addition of L-dopa can be beneficial. Dopamine agonists merit further consideration as adjuncts to antipsychotic drugs in the treatment of schizophrenia.
Jaskiw
George E
GE
Psychiatry Service 116 A(B), Louis Stokes Cleveland VAMC, 10000 Brecksville Road, Brecksville, OH 44141, USA. gxj5@case.edu
Popli
Anand P
AP
D000293:Adolescent; D000328:Adult; D000368:Aged; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage*; D008875:Middle Aged; D012559:Schizophrenia / Q000188:drug therapy*
D007980:Levodopa