Is there any way to predict the onset of schizophrenia?

There may be a way of predicting which teenagers at high risk for full-blown schizophrenia will go on to develop the disease.

Researchers at Columbia University led by Dr. Scott A. Small used MRI scanning to look at the brains of 18 normal adolescents, 18 youths who had schizophrenia, and 18 with preliminary symptoms. These symptoms included paranoid thinking, such as subjects believing someone was looking at them in a troubling way while knowing that’s not a realistic perception. In full schizophrenia, which affects about 1 percent of the population, people are so disconnected from reality that they believe paranoid thoughts are real.

The researchers scanned the high-risk subjects and then followed them for two years. When they looked back at the scans of those who went on to develop psychotic disorders like schizophrenia, they found 70 percent of them had shown unusually high activity in a particular part of the hippocampus, a key brain structure dealing with memory.

“We don’t know if this is diagnostic yet,” said Small, meaning that it’s too soon for the scans to be used as a test. But it does mean, he said, that this hippocampal area, called CA1, is clearly a “hot” spot of extra activity and that this hyperactivity begins several years before the onset of full-fledged schizophrenia. In addition to using brain scans to detect hyperactivity in this area, scientists studying the CA1 region, which is known to be sensitive to an excitement-inducing brain chemical called glutamate, may be able to develop new drugs, as at least one pharmaceutical company is already doing.

“The next step down the road is to understand exactly what is different in the brains of schizophrenics,” said Dr. Bruce Cohen, psychiatrist in chief emeritus at McLean Hospital in Belmont.

If more research shows this type of scanning can detect those likely to develop schizophrenia, it could allow doctors to intervene with medications sooner, he said.