Longitudinal follow-up of neurochemical changes during the first year of antipsychotic treatment in schizophrenia patients with minimal previous medication exposure.
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Reduced frontal N-acetylaspartate (NAA) has been repeatedly found in chronic schizophrenia and suggests neuronal loss or dysfunction. However, the potential confounding effect of antipsychotic drugs on NAA has not been resolved. The few studies of antipsychotic-nai;ve patients are inconclusive. A recent report suggests that antipsychotic drugs may increase NAA in the dorsolateral prefrontal cortex (DLPFC). We studied 10 minimally treated (less than 3 weeks lifetime exposure) schizophrenia patients and 10 normal controls with single-voxel proton magnetic resonance spectroscopy (1H-MRS) of the left frontal and occipital lobes. Concentrations of NAA, Cho, and Cre were determined and corrected for the proportion of cerebrospinal fluid (CSF) in the voxel. Patients were treated in a randomized-controlled double-blind design with either haloperidol or quetiapine. 1H-MRS was repeated within a year. There were no differences in frontal or occipital NAA between patients and controls at baseline. However, frontal NAA was reduced in the schizophrenia group within the first year of treatment. Patients had a clear clinical response to treatment but changes in frontal NAA were not correlated with symptom improvement. The well-described reduced frontal NAA in schizophrenia may not be a trait of the illness but may represent medication effect or progression of the disease.