Quantitative magnetic resonance spectroscopy of schizophrenia:: Relationship between decreased N-acetylaspartate and frontal lobe dysfunction

Numerous studies using proton magnetic resonance spectroscopy (H-1-MRS) have detected signal changes in schizophrenia. However, most studies investigated relative concentrations such as N-acetylaspartate/creatine plus phosphocreatine (NAA/Cre) and choline-containing compounds/creatine plus phosphocreatine (Cho/Cre), and individual metabolite concentrations have not been clarified. Using absolute quantification measurement of H-1-MRS, the aim of the present paper was to demonstrate the changes in metabolite concentrations in the frontal lobe of patients with chronic schizophrenia. The H-1-MRS was performed in the left frontal lobe in 14 patients with schizophrenia and in 13 healthy comparison subjects. Individual MRS peak concentration was quantified based on a frequency-domain fitting program: LCModel. The scores on the Positive and Negative Symptoms Scale and Wisconsin Card Sorting Test were used for clinical assessment. The NAA concentration was reduced in schizophrenic patients (average, 7.94 mmol/L, t = 2.28, P < 0.05) compared with healthy subjects (average = 8.45 mmol/L) while choline, creatine or NAA/Cre ratio did not show any differences. The reduction in NAA concentration had a significant correlation with the severity of negative symptoms (r =-0.536, P < 0.05) and poor performance in Wisconsin Card Sorting Test (r = -0.544, P < 0.05). Using quantitative MRS, decreased NAA concentration was confirmed in the left frontal lobe of schizophrenic patients and was demonstrated to be correlated with negative symptoms and cognitive dysfunction in schizophrenia.