Treatment of negative symptoms in schizophrenia with amisulpride.

Background: The efficacy of low doses of certain neuroleptics in improving negative symptoms is still controversial. This study assessed the efficacy of amisulpride, a benzamide which increases dopaminergic transmission at low doses via presynaptic dopamine receptor blockade, on negative symptoms of schizophrenia.
Method: The study was designed as a parallel-group, double-blind, placebo-controlled trial. Patients had to fulfil DSM-III criteria for schizophrenia, Andreasen's criteria for negative schizophrenia, and to have a total score of at least 75 on the SANS; those treated with neuroleptics or antidepressants underwent a six-week placebo wash-out. One hundred and four in-patients were randomly assigned to amisulpride 100 mg/d, amisulpride 300 mg/d, or placebo for six weeks; 85 patients completed the study.
Results: Both amisulpride doses were significantly more effective than placebo on the primary evaluation criterion (SANS total score, MANOVA P < 0.02). No significant changes were found in positive symptoms or in extrapyramidal symptoms.
Conclusions: Negative symptoms can be improved by low doses of amisulpride, favouring the hypothesis of dopaminergic hypofunction as one of the causes of negative symptoms.