Hypofrontality on topographic EEG in schizophrenia

Abstract

Topographic EEG was performed in 17 DSM-III-R schizophrenic patients and in 15 sex- and age-matched healthy controls. Eleven patients were first-onset (neuroleptic naive) schizophrenics. EEG band power was compared with psychopathology, neuropsychology and neurological soft signs. The EEG was recorded at 14 topographic locations monopolarly and movements of the eye and of the lid were monitored by two bipolar electro-oculogram (EOG) derivations, one vertical and one horizontal. A multivariate correction of EOG artefacts was performed based on regression analysis with respect to EOG channels. Schizophrenic patients showed higher mean and median power in most bands. These differences were marked in the delta band, in the fast alpha and beta bands, in particular at left frontal sites. Delta power at F7 was by far the best separating variable between schizophrenics and controls in a discriminant analysis. Significant positive correlations were found between the Brief Psychiatric Rating Scale scores "Anxiety-depression" and "Activation" and power in the fast bands and negative ones between "Anergia" and the beta bands. Positive significant correlations emerged between the total score in the Negative Symptoms Rating Scale and the amount of delta power, predominantly over the temporal region. Impairment in the Luria-Nebraska neuropsychological scores "Rhythm" and "Memory" correlated highly significantly with EEG band power. No correlations were found between neurological soft signs and EEG band power. Our results are in line with the hypothesis of a hypofrontality in schizophrenia. It is unlikely that these findings are an artefact of prior psychiatric treatment, as they were also observed in first-onset, neuroleptic naive schizophrenics.(ABSTRACT TRUNCATED AT 250 WORDS)

Gamma Power and Cognition in Patients with Schizophrenia and Their First-Degree Relatives

“…This is coherent with previous results displaying elevated power in the faster bands in schizophrenia [15]. Fast oscillations may contribute to forming local neuronal assemblies [38], which, according to our results, may suggest a relative deficit in the integration of activities from distant regions in schizophrenia.…”

“…Higher gamma noise power (corresponding to power unrelated to task performance) has been reported during a P300 task in schizophrenia [14]. Moreover, higher mean power in the faster bands has been reported in this illness [15], as well as a positive correlation between positive symptoms and gamma power responses [16]. It has been suggested that this association may reflect a cortical hyperexcitability that possibly disturbs the conscious experience [11].…”

Source distribution of neuromagnetic slow waves and MEG-delta activity in schizophrenic patients

“…A predominance of delta and theta activity has been reported over posterior scalp sites (e.g., Harris et al 1997;Ulrich and Otto 1984;Westphal et al 1990), but also at central (Karson et al 1987(Karson et al , 1988, left lateral (Schellenberg et al 1989), frontal (Gattaz et al 1992), or frontotemporal (Serafetinides 1984) electrodes. Some studies emphasize that the distribution of slow wave activity is generally diffuse or variable (Elbert et al 1992;Fenton et al 1980;Galderisi et al 1991;Macmahon and Walter 1938).…”

Quantitative EEG in Schizophrenic Patients before and during Pharmacotherapy

“…Negative correlation between delta rhythm and cortical metabolism was also established [26], as well as positive correlation between delta activity and negative symptoms [27].…”