N-acetylaspartate and N-acetylaspartylglutamate deficits in superior temporal cortex in schizophrenia and bipolar disorder: A postmortem study

Background: N-acetylaspartylglutamate is found in neurons and its metabolite N-acetylaspartate, which can be measured by magnetic resonance spectroscopy, is considered a marker of neuronal integrity. Several magnetic resonance spectroscopy studies have found evidence of N-acetylaspartate deficits in schizophrenia. Methods: We employed a high-pressure liquid chromatography method to determine N-acetylaspartate and N-acetylaspartylglutamate in postmortem brain tissues taken from a well-defined series of psychiatric cases. N-acetylaspartate and N-acetylaspartylglutamate concentrations were measured in superior temporal and frontal cortices of patients with schizophrenia, bipolar disorder, and depression and control subjects. Results: N-acetylaspartate was significantly decreased below controls in superior temporal cortex in schizophrenia (p < .01) and bipolar disorder (p < .01), but no deficits were found in frontal cortex. N-acetylaspartylglutamate was significantly decreased only in superior temporal cortex in schizophrenia. Conclusions: The results are consistent with evidence of superior temporal cortex abnormalities in schizophrenia. The finding in bipolar disorder suggests that temporal cortex N-acetylaspartate deficits may be a common feature of psychotic disorders.