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Sniffing out the Causes of Schizophrenia

The sense of smell is now helping to unlock the causes of schizophrenia. Dr. Emily Senay told the Early Show about the latest research in this field.

Scientists from the University of Iowa report in the July 25 Journal of the American Medical Association that they have been able to show how the brains of people with schizophrenia differ from those of normal people when it comes to their emotions. They did it by looking at how each group responded to pleasant smells and unpleasant smells.

Using a combination of PET scans and MRI scans, scientists were able to actually see how the brain was working when people with and without schizophrenia were exposed to good and bad smells--in this case the smell of vanilla or lemon and the smell of dirty socks.

In the brain of schizophrenic patients the researchers found that the limbic area was underactive when exposed to the dirty sock smell. That's the area that is supposed to be very active when a healthy person smells something bad. Instead, the bad smell activated the frontal cortex of the brain in people with schizophrenia. That's the area normally used by healthy people to experience pleasurable scents--which meant that the schizophrenics didn't experience the good smell: only the bad.

It is a classic symptom of the disease that schizophrenics are incapable of appreciating pleasant smells or emotions, and this study actually shows where the problem is inside the brain. The researchers say that this is helping to prove that schizophrenia is a disease that affects key connections between important parts of the brain.

Will this help to diagnose schizophrenics?

Not right now. Schizophrenia is a clinical diagnosis of a complex disease with many different components. The illness is characterized by hallucinations, delusions, disorganized behavior, and the inability to experience emotion that we've discussed.

It's a devastating disease because it hits teens and young adults aged 16 to 25. Hopefully this new study will help point to new directions in understanding the physical causes of schizophrenia so we can better treat the illness.

Why choose schizophrenia to study emotions?

Schizophrenics are often unable to experience pleasure, and if they can't enjoy it they won't participate in most of the things a healthy person finds enjoyable, like food, sex, and music. We don't typically think about responses to emotions as being connected with schizophrenia as much as we do some of the more common symptoms like hallucinations. It's the emotional component that may help us understand the underlying cause of schizophrenia.

Will this knowledge help us treat schizophrenia?

This data will hopefully enable scientists to develop drugs that target some of the underlying physical problems associated with the disease. Right now the drugs available primarily target the symptoms. It will hopefully be possible to devlop new drugs and to better understand the way in which existing drugs work, or why they don't.

What causes schizophrenia?

We don't know the cause. Most psychiatrists believe it's a combination of factors. There's no conclusive evidence to point to any one particular culprit. Possibilities include a combination of genetics, brain injury or illness, and environmental factors.
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