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Frontotemporoparietal asymmetry and lack of illness awareness in schizophrenia

Authors

  • Philip Gerretsen,

    1. Multimodal Imaging Group, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Geriatric Mental Health Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    3. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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  • M. Mallar Chakravarty,

    1. Rotman Research Institute, Baycrest, Toronto, Ontario, Canada
    2. Mouse Imaging Centre (MICe), The Hospital for Sick Children, Toronto, Ontario, Canada
    3. Kimel Family Translational Imaging-Genetics Research Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health
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  • David Mamo,

    1. Multimodal Imaging Group, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Geriatric Mental Health Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    3. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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  • Mahesh Menon,

    1. Multimodal Imaging Group, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
    3. Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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  • Bruce G. Pollock,

    1. Geriatric Mental Health Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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  • Tarek K. Rajji,

    1. Geriatric Mental Health Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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  • Ariel Graff-Guerrero

    Corresponding author
    1. Multimodal Imaging Group, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    2. Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
    3. Schizophrenia Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
    • CAMH—Multimodal Imaging Group, PET Centre, 250 College Street, Toronto, Ontario, Canada M5T 1R8
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Abstract

Introduction: Lack of illness awareness or anosognosia occurs in both schizophrenia and right hemisphere lesions due to stroke, dementia, and traumatic brain injury. In the latter conditions, anosognosia is thought to arise from unilateral hemispheric dysfunction or interhemispheric disequilibrium, which provides an anatomical model for exploring illness unawareness in other neuropsychiatric disorders, such as schizophrenia. Methods: Both voxel-based morphometry using Diffeomorphic Anatomical Registration through Exponentiated Lie Algebra (DARTEL) and a deformation-based morphology analysis of hemispheric asymmetry were performed on 52 treated schizophrenia subjects, exploring the relationship between illness awareness and gray matter volume. Analyses included age, gender, and total intracranial volume as covariates. Results: Hemispheric asymmetry analyses revealed illness unawareness was significantly associated with right < left hemisphere volumes in the anteroinferior temporal lobe (t = 4.83, P = 0.051) using DARTEL, and the dorsolateral prefrontal cortex (t = 5.80, P = 0.003) and parietal lobe (t = 4.3, P = 0.050) using the deformation-based approach. Trend level associations were identified in the right medial prefrontal cortex (t = 4.49, P = 0.127) using DARTEL. Lack of illness awareness was also strongly associated with reduced total white matter volume (r = 0.401, P < 0.01) and illness severity (r = 0.559, P < 0.01). Conclusion: These results suggest a relationship between anosognosia and hemispheric asymmetry in schizophrenia, supporting previous volume-based MRI studies in schizophrenia that found a relationship between illness unawareness and reduced right hemisphere gray matter volume. Functional imaging studies are required to examine the neural mechanisms contributing to these structural observations. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.

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