Objective: The authors investigated the clinical effects of D-cycloserine when added to treatment with conventional neuroleptics, olanzapine, or risperidone for treatment-resistant schizophrenia.
Method: Twenty-four patients participated in a double-blind, placebo-controlled, 6-week crossover trial with D-cycloserine, 50 mg/day, added to their fixed dose of antipsychotic medication. Clinical ratings were performed every 2 weeks.
Results: D-Cycloserine treatment was well tolerated and resulted in a significant reduction in negative symptoms (mean=15%). The degree of improvement did not differ between patients treated with conventional neuroleptics and those treated with olanzapine or risperidone.
Conclusions: These data support the efficacy of the addition of 50 mg/day of D-cycloserine to treatment with conventional neuroleptics and suggest that therapeutic benefits may also be attained when D-cycloserine is added to olanzapine or risperidone.