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 journalBrain.