New light shed on schizophrenia28th January 2009
In a recent study, scientists directly observed the brains of schizophrenics using functional magnetic resonance imaging (fMRI).
MIT scientists observed that, even when undertaking complex tasks, the regions of the brain associated with self-reflection are overactive in schizophrenics.
On the other hand, people without the diagnosis more easily forget themselves when the situation merits it.
The method of identifying schizophrenia sufferers based on this pattern in brain activity may lead to new diagnostic strategies.
The genetic component in the diagnosis of schizophrenia is strong, and immediate family members are 10 times more likely to develop the disorder.
However, scientists do not currently know which genes predict the disease and how they affect the brain.
The researchers studied the brains of three carefully matched groups of subjects.
Patients recently diagnosed with schizophrenia, as well as non-schizophrenic siblings and parents, formed the first two groups.
The control group was composed of asymptomatic, unrelated people.
Using fMRI, subjects were scanned while at rest or while performing tasks of memory of varying difficulties.
The researchers were interested in studying a network of regions known as the default system.
People tend to deactivate this system when performing demanding mental feats, and activity in it is associated with autobiographical memories.
The default system is most active when the mind is allowed to wander or to focus on the self.
When this happens, the brain regions involved become a synchronously active network.
MIT lead researcher John Whitfield-Gabrieli found the default system remains active in patients with schizophrenia, regardless of their mind wandering or not.
They were less able to suppress their self-reflective interpretations of reality, and the region remained active even during sleep.
Not surprisingly, the more connectivity demonstrated by a schizophrenic patient in the default region, the more unstable they were psychologically, and the worse they performed on difficult memory tasks.
Whitfield-Gabrieli said that scientists think this may reflect the difficulties schizophrenics have in directing mental resources away from internal thoughts and feelings and toward the external world in order to perform difficult tasks.
Symptoms of paranoia and hallucinations may also be tied to a hyperactive default system, since these would make external stimuli seem unusually self-relevant.
The default system is also more active than usual in parents and siblings of schizophrenia patients, suggesting that activation of the default system can be tied to genetic factors.
Researchers often have trouble separating the cause of a disease from its effects. The genetic connection lends default system hyperactivity a causal basis, since its overactivity blurs the boundary between internal and external realities.
Whitfield-Gabrieli said that the default system is currently being studied from a variety of perspectives, since its functioning plays into a lot of mental disorders.
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Thursday 4th June 2009 @ 11:19
Is it possible that someone with a hyperactive default system might escape detection due to a higher than average intelligence level?
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Title: New light shed on schizophrenia
Author: Luisetta Mudie
Article Id: 9970
Date Added: 28th Jan 2009