The brains of people who suffer physical illnesses caused by mental or emotional distress function differently, according to research by the University of Cambridge and the University College London (UCL) in the United Kingdom. The study was published on Feb. 25, 2013, in the journal "Brain."
These diseases, also known as 'hysterical' illnesses or psychogenic diseases, can have severe symptoms such as paralysis and painful cramps. Psychogenic diseases appear to be similar to organic illnesses caused by damage to the muscles, nerves, and brain, but don't seem to have a physical cause. These conditions are very difficult to diagnose or treat.
“The processes leading to these disorders are poorly understood, complex and highly variable," said Dr James Rowe from the University of Cambridge. "As a result, treatments are also complex, often lengthy, and in many cases, there is poor recovery. In order to improve treatment of these disorders, it is important to first understand the underlying mechanism,”
Researchers studied people with psychogenic or organic dystonia, and healthy people without dystonia. The organic dystonia patients experienced involuntary, painful, and disabling muscle contractions. The dystonia is caused by a mutation of DYT1 gene. Extensive investigations of the psychogenic patients showed that although they suffered the same symptoms, there was no physical explanation for their disease.
Scientists used PET brain scans on UCL volunteers to measure their brain activity and blood flow. Different foot positions such as the leg held in a dystonic position, in movement, and resting were scanned. Measurements of leg muscle activity were measured at the same time to identify the muscles tht were engaged during the activities.
Researchers found tht the brain function of participants with psychogenic illness was abnormal and very different from the brains of participants with organic illness.
“What struck me was just how very different the abnormal brain function was in patients with the genetic and the psychogenic dystonia," Dr Rowe said. Even more striking was that the differences were there all the time, whether the patients were resting or trying to move.”
In the past, abnormal activity in the prefrontal cortex was thought to be an indicator of psychogenic diseases. Researchers found that this abnormal activity was not a reliable indicator of a psychogenic illness, as it was also present in patients with organic dystonia when they moved their feet.
"It is interesting that, despite the differences, both types of patient had one thing in common - a problem at the front of the brain," Dr Arpan Mehta of the University of Cambridge said. "This area controls attention to our movements and although the abnormality is not unique to psychogenic dystonia, it is part of the problem."
“One in six patients that see a neurologist has a psychogenic illness," Dr Schrag said. "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.”