The new study suggests immune cells are more active in the brains of those at risk for schizophrenia.
The discovery could offer a new approach to treating this chronic, severe and disabling brain disorder that has affected people throughout history.
Schizophrenia occurs in 1% of the general population, but it occurs in 10% of people who have a first-degree relative with the disorder, such as a parent, brother or sister.
Treatment for the disorder so far has focused on an imbalance in the complex, interrelated chemical reactions of the brain. By targeting the neurotransmitters dopamine and glutamate, antipsychotic medicines have been used to control it. However, the drugs often have side effects, and if patients stop taking them, they relapse.
The new findings raise the possibility that early testing of those most at risk could enable them to be treated early enough to avoid the most severe symptoms of the disease.
Researchers at the Medical Research Council's (MRC) Clinical Sciences Centre, based at Imperial College London - in collaboration with colleagues at King's College London - used positron emission tomography (PET) scans to measure levels of activity of immune cells in the brain.
Higher levels of microglia in people with schizophrenia
The immune cells, known as microglia, respond to damage and infection in the brain. They are also responsible for "pruning," where connections between brain cells are rearranged to make them work as well as possible.
The team tested a group of 56 people, of whom some were already diagnosed with schizophrenia, some were at risk of the disease and others had no symptoms or risk of the disorder.
They found that activity levels of microglia in the brain increased according to the severity of symptoms in people with schizophrenia, and that people with diagnosed schizophrenia had high levels of activity of these immune cells in their brain.
Peter Bloomfield, lead author of the study at the MRC Clinical Sciences Centre, says:
"Our findings are particularly exciting because it was previously unknown whether these cells become active before or after onset of the disease. Now we have shown this early involvement, mechanisms of the disease and new medications can hopefully be uncovered."
The effects of schizophrenia can be devastating for patients and families. Patients may experience delusions or hallucinations and believe that other people are reading their minds, controlling their thoughts or plotting to harm them. This can terrify people with the illness and make them withdrawn or extremely agitated.
- Prevalence in the US is around 1.1% of the population
- Of people with schizophrenia, 90% of men will show symptoms by age 30, but only 20% of women
- 10% of people with the disease will take their own lives.
Dangerous or inappropriate behavior can also result, as well as some risk of substance abuse and suicide. Many people with schizophrenia have difficulty holding a job or caring for themselves, so they rely on others for help.
Dr. Oliver Howes, head of the psychiatric imaging group at the MRC Clinical Sciences Centre, describes schizophrenia as a "potentially devastating disorder," for which new treatments are desperately needed. He believes this study is promising, as it suggests that inflammation may lead to schizophrenia and other psychotic disorders, pointing the way for new developments.
The next step will be to test whether anti-inflammatory treatments can target such disorders, to allow the disorders to be treated in a more effective way, or better still, prevented.
Prof. Hugh Perry, chair of the Neuroscience and Mental Health Board at the MRC, says we know that genetic and behavioral factors play a part in schizophrenia, but to find that inflammation in the brain could be a factor brings hope for life-changing treatments. He adds that there could also be implications for other disorders, such as Alzheimer's disease and depression.
Medical News Today recently reported that some antipsychotic drugs prescribed for schizophrenia can cause brain tissue damage.