Dissociation in hysteria and hypnosis
20 October 2010
Conversion disorder/hysteria might be neurologically linked with hypnosis. Neuroscience research on hypnosis could help us make sense of a poorly understood condition that can lead to paralysis, sensory disturbance or memory loss despite their being no detectable damage to the nervous system, according to a new study funded by the Psychiatry Research Trust and published in the Journal of Neurology, Neurosurgery and Psychiatry by researchers Dr Vaughan Bell and Dr Quinton Deeley, of the Institute of Psychiatry at King’s College London. The analysis looked at past neuroscience studies in hypnosis and conversion disorder to identify similarities.
Patients with symptoms that mimic neurological disorders but do not show up in a medical examination as a problem are often diagnosed with 'conversion disorder' or 'conversion hysteria' and have been long associated with emotional distress.
Patients are not faking and they have no control over their symptoms, a fact that led the famous 19th Century French neurologist Jean-Martin Charcot to propose that there may be some neurological link between 'conversion disorder' and hypnosis because hypnotised people also feel they have no control over the effects that are happening to them.
Charcot's ideas fell out of fashion but this new analysis suggests that he may have been on the right track.
This new analysis looked at existing neuroscience studies on both hypnosis and 'conversion disorder' and noticed that a similar pattern emerged, for example when patients or participants tried to use a 'paralysed' limb, or remember information from the period of memory loss, activity in the frontal lobes increased while activity in the key brain areas related to the activity decreased.
What they found was that, in both hypnosis and conversion disorder, the ‘executive functions’, areas that control cognitive processes such as planning, abstract thinking and selecting sensory information located in the frontal lobes, seemed to be temporarily affecting essential functions in other parts of the brain, causing neurological symptoms.
This provides an important clue as to how we can seem to 'lose' essential abilities without having neurological damage. However the mystery remains of why 'conversion disorder' can last for weeks or months, while the effects of hypnosis are temporary, and why the disorder can affect different functions in different people.
This could be because of the emotional disturbance that is associated with 'conversion disorder' although further studies will be needed to understand how strong emotions or difficult experiences could trigger the shut down of other areas by the executive functions reliant on the frontal lobes.
To view the full article, please visit: Dissociation in hysteria and hypnosis: evidence from cognitive neuroscience.