EEG coherence in a mental arithmetic task performance in first episode schizophrenia and schizoaffective disorder

Publication date: Available online 6 September 2018

Source: Clinical Neurophysiology

Author(s): Yuliya Zaytseva, Zhanna Garakh, Vladimir Novototsky-Vlasov, Isaac Ya. Gurovich, Alexander Shmukler, Anna Papaefstathiou, Jiří Horáček, Filip Španiel, Valeria B. Strelets

Abstract

Objectives

To evaluate the coherence values of the cortical bands in patients with first episode schizophrenia and schizoaffective disorder during the performance of a mental arithmetic task.

Method

We analysed EEG coherence in the resting state and subsequently while counting down from 200 in steps of 7 in 32 first episode schizophrenia patients (SZ), 32 patients with first episode schizoaffective disorder (SA) and 40 healthy controls (HC).

Results

Task performance in HC is characterised by decreased coherence in the alpha bands and increased coherence in the beta 2 and gamma bands in frontal sites. In SZ, coherence decreases in the alpha band, whereas in SA it substantially increases in the alpha, beta1, beta 2 and gamma bands.

Conclusions

Despite no differences in performance on a behavioural level, SA patients demonstrate a paradoxical increase in both low and fast frequency bands during the performance of a mental arithmetic task, while, patients with SZ show a decreased coherence in the alpha band, presumably alluding to the excessive excitatory (in SA) and inhibitory (in SZ) mechanisms in cognitive processing.

Significance

The current study provides evidence for the distinction of neurophysiological mechanisms of cognitive processing between SZ and SA.

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