L-dopa in the treatment of negative schizophrenic symptoms: a single-subject experimental study

Adjunctive Sinemet (L-DOPA plus carbidopa) therapy was assessed for a neuroleptic nonresponsive schizophrenic with a longstanding negative syndrome. A twenty-seven week double-blind placebo-controlled reversal design found significant improvement specifically for negative symptoms while treated with combined haloperidol-Sinemet as compared against haloperidol-placebo. The eight-week adjunctive treatment reversed a worsening trend in attention, abstract thinking, passive withdrawal, psychomotor retardation, and a cluster of seven negative parameters, while positive symptoms were unaffected. This seemed to represent more than simple reversal of drug-induced akinesia and underscores the importance of distinguishing between positive and negative syndromes in psychopharmacological research.