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

R.F Sanches,A.W Zuardi,J.E.C Hallak,A.C Santos,J.P.M De Sousa,J.A.S Crippa,D Araújo

doi:10.1590/s0100-879x2008001200015

Abstract

The aim of the present study was to determine whether specific subgroups of schizophrenic patients, grouped according to electrodermal characteristics, show differences in the N-acetylaspartate/creatine plus choline (NAA / (Cr + Cho)) ratios in the frontal, cingulate and perirolandic cortices. Skin conductance levels (SCL) and skin conductance responses to auditory stimulation were measured in 38 patients with schizophrenia and in the same number of matched healthy volunteers (control). All subjects were submitted to multivoxel proton magnetic resonance spectroscopic imaging. When compared to the control group, patients presented significantly lower NAA / (Cr + Cho) ratios in the right dorsolateral prefrontal cortex (schizophrenia = 0.95 +/- 0.03; control = 1.12 +/- 0.04) and in the right (schizophrenia = 0.88 +/- 0.02; control = 0.94 +/- 0.03) and left (schizophrenia = 0.84 +/- 0.03; control = 0.94 +/- 0.03) cingulates. These ratios did not differ between electrodermally responsive and non-responsive patients. When patients were divided into two groups: lower SCL (less than the mean SCL of the control group minus two standard deviations) and normal SCL (similar to the control group), the subgroup with a lower level of SCL showed a lower NAA / (Cr + Cho) ratio in the left cingulate (0.78 +/- 0.05) than the controls (0.95 +/- 0.02, P < 0.05) and the subgroup with normal SCL (0.88 +/- 0.03, P < 0.05). There was a negative correlation between the NAA / (Cr + Cho) ratio in the left cingulate of patients with schizophrenia and the duration of the disease and years under medication. These data suggest the existence of a schizophrenic subgroup characterized by low SCL that could be a consequence of the lower neuronal viability observed in the left cingulate of these patients.

Highlights

The diagnosis of schizophrenia is based on a group of symptoms, which may differ from patient to patient
In one of our studies on electrodermal activity in clinically stabilized schizophrenic patients, we identified a subgroup with low SCR, low skin conductance level (SCL), deficits in selective attention evaluated by the Stroop task performance and predominance of negative symptoms [6]
Prefrontal and anterior cingulate areas were shown to be more activated during the performance of the modified Stroop task in schizophrenic patients than in healthy controls [8]. These results suggest that frontal and cingulate areas could be related to the alterations observed in a subgroup of schizophrenic patients with low SCL and deficits in selective attention

Summary

Introduction

The diagnosis of schizophrenia is based on a group of symptoms, which may differ from patient to patient. The main findings that have been identified in schizophrenia in this field are low skin conductance responses to auditory stimulation (SCR) and abnormalities in the skin conductance level (SCL). These parameters are often higher during psychotic states of schizophrenia [4], suggesting that they may be “state” and not “trait”-related abnormalities. They have a “trait” property since significant stability of SCR and SCL over a 1-year period has been reported in both healthy subjects and schizophrenic patients, especially those who are clinically stabilized [5]

Objectives

Methods

Results

Conclusion