Psychopathology and working memory-induced activation of the prefrontal cortex in schizophrenia-like psychosis of epilepsy: Evidence from magnetoencephalography

Authors

  • Leonides Canuet MD, PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Ryouhei Ishii MD, PhD,

    Corresponding author
    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
      Ryouhei Ishii, MD, PhD, Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Yamadaoka 2-2 D-3, Suita City, Osaka 565-0871, Japan. Email: ishii@psy.med.osaka-u.ac.jp
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  • Masao Iwase MD, PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Koji Ikezawa MD, PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Ryu Kurimoto MD, PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Hidetoshi Takahashi MD, PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Antonio Currais PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
    2. MRC Centre for Neurodegeneration, Department of Neuroscience, Institute of Psychiatry, King's College London, London, UK
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  • Michiyo Azechi MD, PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Yasunori Aoki MD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Takayuki Nakahachi PhD,

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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  • Salvador Soriano PhD,

    1. Department of Pathology and Human Anatomy, Loma Linda University, California, USA
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  • Masatoshi Takeda MD, PhD

    1. Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Osaka, Japan
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Ryouhei Ishii, MD, PhD, Department of Psychiatry and Clinical Neuroscience, Osaka University Graduate School of Medicine, Yamadaoka 2-2 D-3, Suita City, Osaka 565-0871, Japan. Email: ishii@psy.med.osaka-u.ac.jp

Abstract

Aim:  The aim of this study was to investigate whether magnetoencephalographic oscillations underlying working memory dysfunction in the dorsolateral prefrontal cortex (DLPFC) are related to psychopathological disturbance in patients with schizophrenia-like psychosis of epilepsy (SLPE).

Methods:  Twelve patients with SLPE and 14 non-psychotic epilepsy controls participated in this study. Magnetoencephalography was recorded while patients performed a visual working memory (WM) task. Psychopathology was assessed using a four-factor structure of the Brief Psychiatric Rating Scale, and regression analyses were carried out to examine the relative impact of severity of psychopathology on WM-induced activation of the DLPFC.

Results:  We found that activation of the WM-compromising DLPFC, as indicated by increased alpha desynchronization in patients with SLPE compared with their non-psychotic counterparts, showed a positive linear correlation with disorganization symptom scores. This association remained significant after controlling for confounding factors, including age, task performance, IQ, and duration of psychosis.

Conclusion:  Our results indicate that abnormal activation in prefrontal areas engaged during working memory may be critical to domains of psychopathology, in particular disorganized thought-processing in patients with SLPE.

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