Etiology of Conversion Disorder

Somatizationn Graphics courtesy of News Medical Life SciencesOpens in new window

It was earlier mentioned that stress is a potential trigger of the somatic symptom and related disorders. To evaluate this idea, researchers have tested whether conversion disorderOpens in new window might be triggered by overwhelming stress and by difficulty coping with the resultant emotions.

Although those with conversion disorder often report a history of trauma and life events, the rates are not distinct compared to other psychological disorders (van der Hoeven, Broersma, et al., 2015).

Moreover, findings are inconsistent on the coping and emotion profiles of those with conversion disorder (Roberts & Reuber, 2014). In this publication, then, we focus on the idea that conversion disorder symptoms can be produced unconsciously. Then we consider sociocultural factors.

Psychodynamic and Neuroscience Perspectives on the Unconscious in Conversion Disorder

Conversion disorder occupies a central place in psychodynamic theories because the symptoms provide a clear example of the role of the unconscious.

Consider trying to diagnose a woman who says that she awoke one morning with a paralyzed left arm. Assume that a series of neurological tests reveal no neurological disorder. Perhaps she has decided to fake paralysis to achieve some end—this would be an example of malingeringOpens in new window. But what if you believe her? You would almost have to conclude that unconscious processes were operating.

  • On a conscious level, she is telling the truth; she believes that her arm is paralyzed.
  • On an unconscious level, some psychological factor is at work, making her unable to move her arm despite the absence of any physical cause.

Psychodynamic theoryOpens in new window suggests that the physical symptom is a response to an unconscious psychological conflict.

Neuroscience supports the idea that much of our perceptual processing may operate outside our conscious awareness. Take the example of unexplained blindness. The vision system relies on a set of brain regions. If these regions are not coordinated in an overarching conscious fashion, the brain may process some visual input such that the person can do well on certain tests yet still lack a conscious sense of “seeing” certain types of stimuli.

In one neuroimaging case study, a person with a conversion disorder involving blindness showed activity in brain regions involved with processing low levels of visual stimuli (such as lines and squares) but showed diminished activity in higher-level visual cortex regions involved in integrating visual inputs into a consolidated whole (such as a house). Because people may not be processing visual inputs at a higher level, they can truthfully claim that they cannot see, even when tests suggest that they can.

This idea of neural processing outside consciousness can be applied to motor symptoms in conversion disorder. Consider a medically inexplicable tremor. If monitoring systems in the brain do not process the initiation of motor movement, the person could experience the tremor as involuntary (Brown, 2016). Consistent with the idea that people could be unaware of their own initiation of tremors, some people with medically unexplained tremors show diminished activation of association cortices involved in conscious processing (Hallet, 2016).

Although a growing number of small studies provides these types of illustrations that brain systems involved in awareness could be involved, neuroimaging findings remain mixed, and no central neural process has emerged that could explain the lack of conscious awareness across patients with DID (Aybek & Vuilleumier, 2016).

Social and Cultural Factors in Conversion Disorder

Social and cultural factors shape the symptoms of conversion disorder. For example, symptoms of conversion disorder are more common among people from rural areas and people of lower socioeconomic status (Binzer & Kullgren, 1996).

The influence of social factors is also supported by the many documented cases of “mass hysteria,” in which a group of people with close contact, such as schoolmates or coworkers, develop inexplicable medical symptoms that would likely warrant a diagnosis of conversion disorder.

Consider the outbreak of seizure-type symptoms (a relatively common conversion symptom) in a cotton-processing facility, described in 1787. “A girl … put a mouse into the breast of another girl who had great dread of mice. She was immediately thrown into a fit and continued in it with the most violent convulsions for 24 hours.

On the following day, three more girls were seized in the same manner, and the day after, six more.” Within 3 days, 24 girls were affected. “The alarm was so great, that the whole work … was totally stopped” (Dr. St. Clare, 1787, Gentleman’s Magazine, p. 268). Incidents like this suggest that social factors, including modeling, shape how conversion symptoms unfold.

See also:
  1. Nicholson, T., Stone, J., & Kanaan, R.A.A. (2011). Conversion disorder: A problematic diagnosis. Journal of Neurology, Neurosurgery, and Psychiatry, 82, 1267 – 1273.
  2. Stone, J., Vuilleumier, P., & Friedman, J.H. (2010). Conversion disorder: Separatign “how” from “why.” Neurology, 74, 190 – 191.