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Why functional neurological disorder is not feigning or malingering

Nature Reviews Neurology volume 19, pages 246–256 (2023)Cite this article

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An Author Correction to this article was published on 16 May 2023

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Abstract

Functional neurological disorder (FND) is one of the commonest reasons that people seek help from a neurologist and is for many people a lifelong cause of disability and impaired quality of life. Although the evidence base regarding FND pathophysiology, treatment and service development has grown substantially in recent years, a persistent ambivalence remains amongst health professionals and others as to the veracity of symptom reporting in those with FND and whether the symptoms are not, in the end, just the same as feigned symptoms or malingering. Here, we provide our perspective on the range of evidence available, which in our view provides a clear separation between FND and feigning and malingering. We hope this will provide a further important step forward in the clinical and academic approach to people with FND, leading to improved attitudes, knowledge, treatments, care pathways and outcomes.

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Fig. 1: A range of functional neuroimaging and neurophysiological evidence supporting FND as a disorder distinct from feigning.

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Acknowledgements

M.Y. is funded by an MRC CARP award (MR/V037676/1).

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Authors and Affiliations

  1. Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, UK

    Mark J. Edwards

  2. Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, UK

    Mahinda Yogarajah

  3. National Hospital for Neurology and Neurosurgery, University College London Hospitals, London, UK

    Mahinda Yogarajah

  4. Epilepsy Society, London, UK

    Mahinda Yogarajah

  5. Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK

    Jon Stone

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  1. Mark J. Edwards
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The authors contributed equally to all aspects of the article.

Corresponding author

Correspondence to Mark J. Edwards.

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Competing interests

M.J.E. does medical expert reporting in personal injury and clinical negligence cases, including in cases of functional neurological disorder (FND). M.J.E. has shares in Brain & Mind, which provides neuropsychiatric and neurological rehabilitation in the independent medical sector, including in people with functional neurological disorder. M.J.E. has received financial support for lectures from the International Parkinson’s and Movement Disorders Society and the FND Society (FNDS). M.J.E. receives royalties from Oxford University Press for his book The Oxford Specialist Handbook of Parkinson’s Disease and Other Movement Disorder. M.J.E. receives grant funding, including for studies related to FND, from the National Institute for Health and Care Research (NIHR) and the Medical Research Council (MRC). M.J.E. is an associate editor of the European Journal of Neurology. M.J.E. is a member of the international executive committee of the International Parkinson’s and Movement Disorders Society and a board member of the FNDS. M.J.E. is on the medical advisory boards of the charities FND Hope UK and Dystonia UK. J.S. reports royalties from UpToDate for articles on FND and runs a free self-help website for people with FND. J.S. carries out independent personal injury and clinical negligence medicolegal work including in relation to FND where questions of feigning commonly arise. He is secretary of the FND Society and is on the medical advisory boards for FND Hope and FND Action. J.S. has received grant funding for projects on FND from NIHR, European Union, and Scottish Government. J.S. is a career research fellow funded by the Chief Scientist Office in Scotland. M.Y. receives grant funding for studies into functional neurological disorder and functional seizures from the MRC, the NIH and the Association of British Neurologists. He carries out independent medico-legal work for the criminal, civil and family courts, some of which involves functional neurological disorders. He also receives royalties from Elsevier for two editions of the Crash Course Neurology textbook.

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Glossary

Drift diffusion model

A way of modelling the cognitive processes involved in a two-choice decision task.

Factitious disorder

Deceptive falsification of physical or psychological symptoms or signs, or self-induced injury or illness in the absence of an external reward, but typically to receive health care or care from others.

Feedforward model

A model of movement and sensation that relates to predictions about expected movement and sensation, which are integrated with feedback from actual sensory input.

Feigning

The deliberate and voluntary production of physical symptoms and signs in order to deceive.

Go/no-go task

An experimental paradigm in which participants are given a cue to get ready to move and then are given either a ‘go’ cue, upon which they should move, or a ‘no-go’ cue, which means that they should withhold the prepared movement.

Hoover’s sign

A sign of functional leg weakness in which voluntary hip extension is weak when tested directly but returns to normal power when the same movement is triggered by contralateral hip flexion.

Locomotor after-effects

A change in gait pattern that is triggered by exposure to a stimulus such as walking on split belt treadmill with each leg going at a different speed, which then lasts after the stimulus is withdrawn.

Malingering

Deceptive falsification of physical or psychological symptoms for external reward. It is not a diagnostic category in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition.

Psychophysical

Study of the interaction between physical stimuli and their psychological correlates.

Psychophysiological

Study of the relationship between physiological phenomena and psychological phenomena.

Temporal discrimination threshold

The minimum time between two sensory stimuli that a person can perceive.

Tremor entrainment test

A test for functional tremor in which the frequency of the tremor changes to match the frequency of an externally paced tapping movement.

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Edwards, M.J., Yogarajah, M. & Stone, J. Why functional neurological disorder is not feigning or malingering. Nat Rev Neurol 19, 246–256 (2023). https://doi.org/10.1038/s41582-022-00765-z

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