WEDNESDAY, March 10 (HealthDayNews) -- Cell damage caused by free radicals could be the reason why some people with schizophrenia don't respond to treatment, says a University of Pennsylvania study.

The researchers found evidence of a destructive biological process similar to that seen in people with Alzheimer's disease and other major neurodegenerative disorders.

Free radicals are naturally occurring chemicals in the body that have been linked to a variety of health problems.

In this study, researchers conducted tests on the brains of deceased elderly people who had had schizophrenia and hadn't responded well to treatment and the brains of deceased elderly people with no known psychiatric disorders.

The brains of those with schizophrenia showed far greater indication of "oxidative DNA damage," something that occurs when free radicals overwhelm a cell's "antioxidant" capabilities.

This damage was evident in neurons located in a part of the brain called the hippocampus, which is associated with complex memory activities. The number of neurons with evidence of this damage was 10 times higher in the brains of those with schizophrenia than in the normal brains.

The study was published in a recent issue of the American Journal of Geriatric Psychiatry.

More information

The National Alliance for the Mentally Ill has more about schizophrenia.