Proton magnetic resonance spectroscopy of the frontal lobe in schizophrenics: a critical review of the methodology

Abstract

Schizophrenic patients undergoing proton magnetic resonance spectroscopy show alterations in N-acetyl aspartate levels in several brain regions, indicating neuronal dysfunction. The present review focuses on the main proton magnetic resonance spectroscopy studies in the frontal lobe of schizophrenics. A MEDLINE search, from 1991 to March 2004, was carried out using the key-words spectroscopy and schizophrenia and proton and frontal. In addition, articles cited in the reference list of the studies obtained through MEDLINE were included. As a result, 27 articles were selected. The results were inconsistent, 19 papers reporting changes in the N-acetyl aspartate levels, while 8 reported no change. Methodological analysis led to the conclusion that the discrepancy may be due the following factors: (i) number of participants; (ii) variation in the clinical and demographic characteristics of the groups; (iii) little standardization of the acquisition parameters of spectroscopy. Overall, studies that fulfill strict methodological criteria show N-acetyl aspartate decrease in the frontal lobe of male schizophrenics.

Proton MRS in twin pairs discordant for schizophrenia

“…20 In particular, most (8 of 15) published studies of the hippocampus report a significant reduction of NAA in patients. The present findings therefore add to evidence of NAA abnormalities in schizophrenia, [16][17][18][19][20] in subjects at risk for schizophrenia, [27][28][29]31 and extend them to the particular case of twin siblings. But the direction of our NAA findings (excess vs deficit) is at odds with the abovecited literature.…”

“…Reviews of the MRS schizophrenia literature to date [16][17][18][19][20] show ample evidence of abnormalities in NAA; suggestive evidence for abnormalities in glutamate þ glutamine (Glx), Cr and choline (Cho); and scant evidence for abnormalities in mI. In particular, bilateral deficits in NAA, NAA/Cr and/or NAA/Cho in the 'dorsolateral prefrontal' region (usually middle frontal gyrus) and mesial temporal lobes (predominantly hippocampus) were detected in early work in adult schizophrenia 21 and have since become fairly accepted.…”

Metabolic alterations associated with schizophrenia: a critical evaluation of proton magnetic resonance spectroscopy studies

“…The spatial resolution in 1 H‐MRS remains a problem, especially in studies using larger voxel (Sanches et al . ). Furthermore, control participants and patient groups assessed serially often differ in the exact amount of each tissue in the specified voxel and the localization of the VOI lacks sufficient accuracy to assure a direct comparison (Marshall et al .…”

“…However, many studies found decreased NAA levels as in CSP (Sanches et al . ; Jessen et al . ), in early and late at‐risk syndrome patients that converted to schizophrenia (Jessen et al .…”

Proton magnetic resonance spectroscopy of the frontal, cingulate and perirolandic cortices and its relationship to skin conductance in patients with schizophrenia

“…Relative ratios may be calculated by dividing NAA concentrations by the concentration of a metabolite whose concentration would be expected to be stable, such as creatine (Cr) or choline (Cho). However, a reduction of NAA in the frontal and cingulate areas of patients with schizophrenia has not been found consistently (16)(17)(18). These contradictory findings may be due, in part, to the heterogeneous characteristics of schizophrenia, or to different methodological approaches.…”