Conversion Disorder: A Cognitive Neuropsychiatric Approach

Conversion disorder (?hysteria?) is a very common, very disabling condition, which is thought to occur when emotional problems are ?converted? into physical symptoms such as paralysis or blindness. Though it is as common and as disabling as ever, there has been very little research on it since the 19th century. The process by which it occurs remains mysterious, and there are no established treatments. Most patients with the disorder do not believe they have it, and do not see their problems as mental at all. We wish to examine this conversion process to see if it has some basis in modern neuroscience. If the conversion model is correct, then we would expect patients to have more life stresses of certain types leading up to their developing the disorder. This can be difficult to prove because of the unreliability of people?s recall, and because we know this group tend to deny the relevance of such stresses. We propose to address this with a standardised interview, the Life Events & Difficulties Schedule, which is a valid and reliable way of accessing problems from subjects? pasts. The conversion model proposes that these experiences are emotionally repressed. Using brain scanning, we wish to examine patients while they recall those experiences to see if they do recall them in a less emotional way than other people, even though this may be something they do not acknowledge. We will also examine whether recall brings on their symptoms - making their paralysis worse, for example. If this is successful we expect it will make the diagnosis much more acceptable and understandable to patients, and open the field to the research it sorely needs.

Conversion disorder is thought to involve the conversion of psychological distress into somatic symptoms. Though the prevalence and disability of the disorder are profound, our understanding of the disorder has barely advanced in the last century. There has been very little research into the mechanisms that might underlie it, particularly the core principle of psychogenic conversion. This is largely because of the difficulties in investigating a psychological process from the subject?s past whose importance the subject denies. We plan to address this by examining the recall of these events in the present, using a case-control design. We will use a standardised, reliable and validated method of assessing the life stressors that may have preceded the onset of symptoms (the Life Events and Difficulties Schedule), which significantly overcomes the problem of biased recall (repression) that is hypothesised to operate in this group. This will allow us not only to determine whether there is an increased incidence of such events compared with the general population, but will also provide us with a source of events that might have been ?converted?. We will then use functional MRI to examine the recall of these events, to see whether they are indeed processed in an emotionally abnormal way, when compared with other events from the patients recent past, and compared with healthy controls - consistent with the idea that they have been repressed. We will also look for motor or sensory correlates of this recall ? consistent with the idea that the stress is being converted.