Objectives: A study of N-acetyl-aspartate (NAA) can provide data of interest about cortical alterations in psychotic illnesses. Although a decreased NAA level in the cerebral cortex is a replicated finding in chronic schizophrenia, the data are less consistent for bipolar disease. On the other hand, it is likely that NAA values in schizophrenia may differ in men and women.
Methods: We used proton magnetic resonance spectroscopy ((1)H MRS) to examine NAA levels in the prefrontal cortex in two groups of male patients, one with schizophrenia (n=11) and the other with bipolar disorder (n=13) of similar duration, and compared them to a sample of healthy control males (n=10). Additionally, we compared the degree of structural deviations from normal volumes of gray matter (GM) and cerebrospinal fluid (CSF) in the dorsolateral prefrontal cortex.
Results: Compared to controls, schizophrenia and bipolar patients presented decreased NAA to creatine ratios, while only the schizophrenia group showed an increase in CSF in the dorsolateral prefrontal region. There were no differences in choline to creatine ratios among the groups.
Conclusions: These data suggest that the decrease in NAA in the prefrontal region may be similar in schizophrenia and bipolar disorder, at least in the chronic state. However, cortical CSF may be markedly increased in schizophrenia patients.