NMDA-enhancing Treatment for Cognitive Dysfunction of Schizophrenia

Cognitive impairment, the core psychopathology and the outcome determinant of schizophrenia, usually persists in schizophrenia patients even during symptomatic remission. Cognitive impairment associated with schizophrenia (CIAS) is an important therapeutic target; and hypofunction of N-methyl-D-aspartate receptor (NMDAR) is a key factor of CIAS. Whether NMDAR-enhancing treatment can truly improve cognitive function needs to be tested in schizophrenia patients during symptomatic remission. This study aims to examine the efficacy and safety of an NMDA-enhancer (NMDAE) for the treatment of CIAS in schizophrenia patients during symptomatic remission. The subjects are the patients with schizophrenia during symptomatic remission. They keep their original treatment and are randomly, double-blindly assigned into two treatment groups for 12 weeks: (1) NMDAE, or (2) placebo. At weeks 0 and 12, 7 cognitive domains will be measured. At weeks 0, 4, 8, and 12, Global Assessment of Function, Quality of Life Scale, various clinical-symptom rating scales, and side effects scales will be measured too. Chi-square (or Fisher's exact test) will be used to compare differences of categorical variables and t-test (or Mann-Whitney test if the distribution is not normal) for continuous variables between treatment groups. Mean changes from baseline in repeated-measure assessments will be assessed using the generalized estimating equation (GEE). All p values for clinical measures will be based on two-tailed tests with a significance level of 0.05.