Australian research has found that the immune system, and inflammation, might be linked to schizophrenia.

Some people with schizophrenia have an increase in white blood cells, an important part of the immune system, in their brain.

Schizophrenia affects approximately 23 million people worldwide and no single cause has been found to date.

Australian scientists have announced the findings of a study they describe as one of the biggest breakthroughs in schizophrenia research in recent times.

The research suggests that some people with schizophrenia have an increase in white blood cells in their brain.

These white blood cells are an important part of the immune system and the researchers believe that this could signal an important role for inflammation in schizophrenia.

The study published in Molecular Psychiatry has the potential to transform global schizophrenia research and open new avenues for developing targeted immune cell therapies.

Approximately 23 million people worldwide are affected by schizophrenia, according to the World Health Organisation. No single cause of schizophrenia has been identified, and this has prevented the development of a cure.

Most scientists believed up until now that immune cells were independent of brain pathology in psychotic illnesses. Shutterstock

The current treatments for schizophrenia are designed to suppress symptoms rather than target underlying causes. These drugs only partially relieve symptoms and can produce severe side effects.

Professor Cynthia Shannon Weickert at Neuroscience Research Australia (NeuRA) says most scientists have had a long held belief that immune cells were independent from the brain pathology in psychotic illnesses.

"In our study, we challenged this assumption that immune cells were independent of the brain in psychiatric illness and made an exciting discovery," she says.

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"We identified immune cells as a new player in the brain pathology of schizophrenia."

Professor Shannon Weickert says immune cells have previously been ignored as they had long been viewed simply as travellers just thought to be passing by, undertaking surveillance work. They have never been a suspect until now.

"To find immune cells along the blood brain barrier in increased amounts in people with schizophrenia is an exciting discovery," she says.

"It suggests immune cells themselves may be producing these inflammatory signals in the brains of people living with schizophrenia.

Current treatments for schizophrenia suppress symptoms rather than targeting the causes, however this new finding could help change that. Matt Cardy/Getty Images

"We have observed in people with schizophrenia, the glial cells, one of the local residents, become inflamed and produce distress signals which change the status of the endothelial cells.

"We think this may cause the endothelial cells to extend sticky tentacles, so when the immune cells travel by some are captured. These cells may transmigrate across the blood brain barrier entering the brain in greater amounts in some people with schizophrenia compared to people without the disorder."