Simpler way out (Image: Laural Ani/Getty)

AS MANY as 1 in 10 cases of schizophrenia may be triggered by an autoimmune reaction against brain cells, according to early trial results shared with New Scientist.

The finding offers the possibility of gentler treatments for this devastating mental illness. Last month, doctors at a conference at the Royal Society of Medicine in London were told to consider an autoimmune cause when people first show symptoms of schizophrenia.

People with schizophrenia experience symptoms of psychosis, such as hallucinations, delusions and paranoia. It affects 1 per cent of people in the West and is thought to be caused by overactive dopamine signalling pathways in the brain. Anti-psychotic drugs don’t always work well and have serious side effects.


Previous studies had found that antibodies that target the NMDA receptor on neurons trigger brain inflammation, leading to seizures, comas – and sometimes psychosis (Annals of Neurology, doi.org/fdgnpc).

In the past few years, these antibodies have also been found in the blood of people whose only symptom is psychosis. In 2010, Belinda Lennox at the University of Oxford tested 46 people with recent onset of psychosis for antibodies known to target neurons. Three people – about 6 per cent – tested positive (Neurology, doi.org/chs532).

“The question is whether a larger percentage of cases might have other antibodies which we cannot yet detect,” says Robin Murray at the Institute of Psychiatry in London, who wasn’t involved in the research.

Now Lennox is conducting a larger trial. Early results suggest other antibodies could well be involved.

This time Lennox is testing 240 people with schizophrenia for antibodies to their own brain cells. Again, around 6 per cent have known antibodies.

But she is also finding that some blood samples test negative for the known antibodies, yet still show an immunological reaction to brain cells in the lab. That suggests they contain unidentified antibodies, she says, which could bring the number of affected cases up to around 1 in 10.

Immuno-suppressive treatments, such as removing antibodies from the blood, have successfully been used to treat some cases of schizophrenia caused by an immune response. But only a handful of cases have so far been treated in this way, and no randomised trials have been conducted.

Suppressing the immune response can cause the psychiatric symptoms of schizophrenia to go away

The antibodies are rarely seen in people who have had schizophrenia for several years, suggesting that immuno-suppressive treatment needs to start early to work. Lennox speculates that after a while the antibodies die away but the damage persists.

She recommends widespread testing for these antibodies. Without it, many more cases may be missed, Angela Vincent, at the University of Oxford, told last month’s conference.

It is still unclear why some people develop these immune responses to their own brain cells, but Lennox is excited by the treatment prospects.

But Chris Frith of University College London cautions that such antibodies have so far only been identified in a small proportion of cases. “I’m sure schizophrenia has many different causes,” he says.

This article appeared in print under the headline “Immune trigger for schizophrenia”