New study examines Freud's theory of hysteria

This research is the first to robustly assess this key theory on what is now known as Conversion Disorder (CD) or, increasingly, as Functional Neurological Disorder (FND).

CD is a complex and much misunderstood disorder at the interface of neurology and psychiatry. Neurological symptoms occur in the absence of identifiable neurological disease and the disorder has historically been assumed to be psychological in origin -- although this is being increasingly challenged. It is one of the most frequent causes of neurological symptoms but receives a fraction of the research attention of other common and disabling disorders, such as Multiple Sclerosis. As a result, the causes of CD remains largely unknown and there are few effective treatments.

This study of 43 CD patients with physical weakness, 28 depression patients and 28 healthy controls used the Life Events and Difficulties Schedule (LEDS) -- the most robust method for detecting, categorising and rating severity of stressors around the time of symptom onset. Critically this method relies on a trained researcher gathering comprehensive detail of the person's life and relationships before systematically enquiring about all conceivable forms of stress. Therefore the true severity of superficially innocuous events, such as a family reunion, can be revealed by the complexity of family relationships and past events.

The researchers found that patients with CD had experienced significantly more severe life events than controls, and this relative difference increased the closer they looked to symptom onset. In the month before symptom onset at least one severe event was identified in 56% of CD patients, 21% of depression patients and 18% of healthy controls. However, in 9% of CD patients no stressors were identified in the year before symptom onset.

Dr Tim Nicholson, a Neuropsychiatrist from the Institute of Psychiatry, Psychology & Neuroscience at King's College London, said: "The fact that we found more stressors in CD patients compared to controls supports their relevance to the onset of the disorder, particularly as the frequency of events dramatically increased the closer we looked to symptom onset."

"However, it is particularly important that despite using such a thorough method, and in a population who had been referred to a psychiatrist, a significant proportion of the CD patients -- 9% -- did not have an identifiable stressor. This finding is a big blow to Freud's theory that such traumas are the sole cause of this disorder. It also chimes with emerging voices of patients who are now clearly expressing the distress that can be caused when it is assumed that there must be an underlying causative stressor. When one is not found it has been assumed by many clinicians that it is being 'repressed' from consciousness or, even more damagingly, being actively denied by the patient."

Bridget Mildon, founder and president of FND Hope (the leading patient organisation for CD), said: "The lack of understanding about the causes of this highly debilitating disorder makes research like this vital. While stress can trigger many illnesses this is one disorder where those without identifiable stressors potentially hold the key to many questions. More research is critical if we are to unravel the mystery behind functional neurological symptoms."

The potential mechanism by which stress can cause such symptoms has been investigated in previous work by Dr Nicholson and colleagues in 'functional' brain imaging studies, that look at brain activations in patients using MRI scans. This research found evidence that CD patients activate parts of their brains differently, particularly areas involved in emotion processing, when thinking back to stressful events that were considered relevant to the onset of their symptoms compared to equally severe events.

Dr Nicholson said: "So, was Freud wrong about Hysteria? The answer is both yes and no. The results definitively show that Freud was wrong that stress will always be found. However, our study indicates he might have been right in that stressors or trauma are likely to be involved in causing CD -- at least in some patients. The challenge is now to work out what the cause, or causes, are in a given individual and then develop tailored treatments that can hopefully be more effective than those we currently offer for this common and misunderstood disorder."