Psychogenic diseases linked to abnormal brain activity

25 February 2013

Image showing activity in the brain

People with psychogenic diseases (that is, physical illnesses stemming from emotional or mental stresses) have brains that function differently to individuals with organic diseases, according to new research from University College London (UCL) and the University of Cambridge. 

Psychogenic diseases, formerly known as 'hysterical' illnesses, may look very similar to genetic diseases of the nervous system or to illnesses caused by damage to the nerves, brain or muscles. They can result in many severe symptoms, such as painful cramps or paralysis. However, unlike organic diseases, psychogenic diseases do not have any apparent physical cause, making them difficult to diagnose and even more difficult to treat. 

The researchers studied people with either psychogenic or organic dystonia (a movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures), as well as healthy people with no dystonia. Both types of dystonia caused painful and disabling muscle contractions affecting the leg. 

The organic patient group had a gene mutation that caused their dystonia. The psychogenic patients had the symptoms of dystonia but did not have any physical explanation for the disease, even after extensive investigations. 

The scientists performed PET brain scans on the volunteers to measure their blood flow and brain activity. The participants were scanned with three different foot positions: resting, moving their foot and holding their leg in a dystonic position. The electrical activity of the leg muscles was measured at the same time to determine which muscles were engaged during the scans. 

The researchers found that the brain function of individuals with the psychogenic illness was very different to that of the individuals with the organic (genetic) disease. 

Anette Schrag of the UCL Institute of Neurology explained: "Our findings open up a way for researchers to learn how psychological factors can, by changing brain function, lead to physical problems." 

James Rowe of the University of Cambridge said: "What struck me was just how very different the abnormal brain function was in patients with the genetic and the psychogenic dystonia. Even more striking was that the differences were there all the time, whether the patients were resting or trying to move." 

This type of illness is very common. Dr Schrag added: "One in six patients that see a neurologist has a psychogenic illness. They are as ill as someone with organic disease, but with a different cause and different treatment needs. Understanding these disorders, diagnosing them early and finding the right treatment are all clearly very important. We are hopeful that these results might help doctors and patients understand the mechanism leading to this disorder, and guide better treatments." 

The research, The functional neuroimaging correlates of psychogenic versus organic dystonia, was published in the journal Brain.

  • UCL and Cambridge University scientists have found differences in the brain function of people with psychogenic illnesses compared with those with organic diseases. 
  • Organic diseases involve a physiological change to bodily organs or tissues, while psychogenic diseases are physical illnesses that are caused by emotional or mental stresses. 
  • It's hoped that improving understanding of psychogenic diseases and their causes will speed up diagnoses and help clinicians to improve patient treatments.