Response inhibition in motor conversion disorder

Authors

  • Valerie Voon MD, PhD,

    Corresponding author
    1. Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, United Kingdom
    2. Cambridgeshire and Peterborough Foundation Trust, University of Cambridge, Cambridge, United Kingdom
    3. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
    • Department of Psychiatry, University of Cambridge, Cambridge, United Kingdom
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  • Vindhya Ekanayake MA,

    1. Purdue University, West Lafayette, Indiana, USA
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  • Edythe Wiggs PhD,

    1. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Sarah Kranick MD,

    1. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Rezvan Ameli PhD,

    1. National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
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  • Neil A. Harrison MD, PhD,

    1. Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom
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  • Mark Hallett MD

    1. National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Funding agencies: This study was supported by the Intramural National Institutes of Health.

  • Relevant conflicts of interest/financial disclosures: Valerie Voon is a Wellcome Trust Fellow.

Correspondence to: Dr. Valerie Voon, Addenbrookes Hospital, Level E4, Box 189, Cambridge, UK, CB2 0QQ; voonval@gmail.com

ABSTRACT

Conversion disorders (CDs) are unexplained neurological symptoms presumed to be related to a psychological issue. Studies focusing on conversion paralysis have suggested potential impairments in motor initiation or execution. Here we studied CD patients with aberrant or excessive motor movements and focused on motor response inhibition. We also assessed cognitive measures in multiple domains. We compared 30 CD patients and 30 age-, sex-, and education-matched healthy volunteers on a motor response inhibition task (go/no go), along with verbal motor response inhibition (color-word interference) and measures of attention, sustained attention, processing speed, language, memory, visuospatial processing, and executive function including planning and verbal fluency. CD patients had greater impairments in commission errors on the go/no go task (P < .001) compared with healthy volunteers, which remained significant after Bonferroni correction for multiple comparisons and after controlling for attention, sustained attention, depression, and anxiety. There were no significant differences in other cognitive measures. We highlight a specific deficit in motor response inhibition that may play a role in impaired inhibition of unwanted movement such as the excessive and aberrant movements seen in motor conversion. Patients with nonepileptic seizures, a different form of conversion disorder, are commonly reported to have lower IQ and multiple cognitive deficits. Our results point toward potential differences between conversion disorder subgroups. © 2013 Movement Disorder Society

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