The effect of atypical antipsychotics on brain N-acetylaspartate levels in antipsychotic-naïve first-episode patients with schizophrenia: a preliminary study

PURPOSE To investigate the correlates of a clinical therapeutic response by using the parameters measured by proton magnetic resonance spectroscopy after the administration of atypical antipsychotics. PATIENTS AND METHODS Twenty-five antipsychotic-naïve first-episode patients with schizophrenia were monitored for 12 months. The patients were evaluated using (1)H magnetic resonance spectroscopy in the dorsolateral prefrontal cortex and Positive and Negative Syndrome Scale, Clinical Global Impression Scale of Severity, Tower of London - Drexel University, Letter-Number Span Test, Trail Making Test A, and Personal and Social Performance Scale. They were administered atypical antipsychotics, starting with quetiapine. In the absence of a therapeutic response, another antipsychotic was introduced. RESULTS After 12 study months, the N-acetylaspartate/creatine (NAA/Cr) level did not significantly change at the whole-group level. Additional analysis revealed a significant rise in the NAA/Cr level in the study group that stayed on the same antipsychotic throughout the study course (P=0.008) and a significant drop in NAA/Cr in the study group that switched antipsychotics (P=0.005). On the whole-group level, no significant correlations between NAA/Cr values and other scores were found at either baseline or after 12 study months. CONCLUSION One-year treatment with atypical antipsychotics administered to antipsychotic-naïve patients didn't result in a significant rise in the NAA/Cr ratio. However, a significant rise was witnessed in the study group in which a satisfactory therapeutic response had been achieved with a single antipsychotic administration.