Addition of memantine to antipsychotic treatment in schizophrenia inpatients with residual symptoms: A preliminary study

Background: Schizophrenia is comprised of several debilitating symptoms. Antipsychotics offer an effective treatment for positive symptoms, white the negative signs and cognitive deficits are usually treatment-resistant. It was suggested that glutamate dysregulation may be involved in the neuropathology of schizophrenia, mainly through NMDA dysfunction. We hypothesized that addition of memantine, a weak non-selective NMDA receptor antagonist approved for dementia, to antipsychotics would improve the clinical status of un-remitted schizophrenia patients, notably the negative signs and cognitive deficits. Methods: Seven schizophrenia patients, were included in a six-week open-label study, with weekly increasing dosage (5, 10, 15, 20 mg) of memantine added to their on-going antipsychotic treatment. Results: We found a significant improvement of the PANSS score (baseline 116.28 +/- 21.9 vs. 97.86 +/- 24.48 after six weeks, t = 5.98, p<0.001) with the most prominent improvement (21%) in negative signs sub-scale (baseline 40 +/- 6.38 vs. 31.71 +/- 7.76 after six weeks, t=5.87, p<0.001). Cognitive status, measured with the Neurobehavioral Cognitive Examination (NCSE) and Clock Drawing Test (CDT) showed no improvement. Conclusion: Memantine addition to antipsychotic treatment, in schizophrenia patients might improve their clinical status, primarily the negative signs, but not their cognitive deficits. Further research is needed to replicate these observations. (C) 2007 Elsevier B.V. and ECNP. All rights reserved.