ABSTRACT
OBJECTIVES: To investigate neurophysiological parameters which possibly distinguish subtypes I and II of patients with a bipolar disorder, and contrast the findings with observations from a group of schizophrenic patients and a group of healthy controls. METHODS: Sixty-six volunteers underwent a MRI scan to determine the number and location of white matter lesions (WSL). A electrophysiological registration was made while all volunteers performed a auditory 'oddball' task, and the amplitude of the resulting P300 wave was compared. RESULTS: Earlier reports of higher numbers of WSL in bipolar disorder were not replicated in this study. Subtypes I and II showed a different P300 amplitude and subtype I resembled the results of the schizophrenia group. CONCLUSION: Bipolar patients in remission have a functional brain disorder that is expressed by a change in physiological response to external stimuli.
ABSTRACT
Recent studies of cerebral pathology in patients with schizophrenia have focused on symptomatological and electrophysiological correlates of reduced temporal lobe structure volumes. Volume deficits of the left superior temporal gyrus have been correlated with auditory hallucinations as well as to left-sided P300 amplitude reduction. However, caution is needed to interpret correlational data as evidence of a specific relationship. Therefore, a controlled study was undertaken on schizophrenic patients with and without auditory hallucinations. MRI-defined volumes of the left superior temporal gyrus and other temporal lobe structures were quantified from 3-mm coronal slices in 15 schizophrenic patients with chronic auditory hallucinations (hallucinators), 15 schizophrenic patients without auditory hallucinations (nonhallucinators) and 17 healthy controls. In all subjects a simple oddball paradigm was used to elicit P300 responses at temporal and centro-parietal electrode sites. No evidence was found for volume reductions of temporal lobe structures in the combined patient group compared with controls, or in the hallucinators compared with the nonhallucinators. The patients did show left P300 amplitude reduction compared with controls, particularly in the hallucinator group. Correlations between volumes of left temporal lobe structures and left P300 amplitudes were low and not significant. The results of the present study do not indicate that auditory hallucinations and associated abnormal electrophysiological activity are the consequence of atrophy of localized temporal lobe structures. However, replication in a larger sample of subjects is needed before firm conclusions can be drawn.
