Seoul National University Bundang Hospital (SNUBH) said it has identified the differences in the causes of the development of schizophrenia and stressed that hospitals should select the appropriate antipsychotic drugs to treat the patients accordingly.

Professors Kim Eui-tae (left) and Kwon Jun-soo

Schizophrenia refers to a mental illness that causes abnormalities in various aspects, such as thoughts, feelings, perceptions, and behaviors due to multiple causes.

Although much of the pathophysiological mechanism has not yet been revealed, doctors believe that the dopamine delivery system, the over-activity of dopamine, and abnormal structural and functional connections as primary factors to the disease. Hospitals usually use antipsychotic drugs that control the dopamine balance to treat the disease and monitor for any discomfort or side effects caused by the medication.

Such monitoring is essential as the treatment response to the antipsychotic drug can come out in various ways, and there are many differences in the cause and course of the disease according to the difference in treatment responsiveness.

In detail, hospitals divide schizophrenia into two parts -- therapeutic responsive schizophrenia in which patients respond to the first antipsychotic drug treatment, and therapeutic resistant schizophrenia where patients respond only to clozapine and do not respond to the primary treatment. However, it is difficult to identify the treatment response before the patient receives their first treatment. Therefore, treatment-resistant patients have a delay in receiving the right treatment.

To resolve such issues, the team, led by Professor Kim Eui-tae at the hospital, conducted a study to determine the differences in the causes of schizophrenia through the characteristics of patients who responded well to first-line antipsychotic drugs and those that don't.

Professor Kwon Jun-soo at Seoul National University also participated in the study.

The team first used magnetic resonance imaging and positron emission tomography to analyze the correlation between prefrontal volume and dopamine production in schizophrenia patients.

Patients who responded well to antipsychotic medications had higher dopamine production as their frontal lobe volume was smaller than regular people. However, the team did not observe such correlations in patients with treatment-resistant schizophrenia.

The background of these findings suggests that frontal lobe abnormalities and striatal dysplasias in treatment-responsive patients cause problems with the dopamine system and cause overproduction, whereas, in patients with treatment-resistant patients, the illness develops differently.

"Hospitals should maintain antipsychotic drug treatment for patients who have schizophrenia caused by decreased frontal lobe volume and excess dopamine production, which account for 70 percent of the total patient population," Professor Kim said. "On the other hand, treatment-resistant patients who have symptoms other than dopamine activation need to take other treatments such as clozapine rather than the primary antipsychotics."

The team also stressed that the study, together with the King's College London team in the United Kingdom, provided statistical significance by comparing the U.K. and Korean patients.

The results of the study were published in Molecular Psychiatry.

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