'Schizophrenia Gene' Discovery May Bring New Treatments For Mental Illness

A new study published in the journal Nature examines a gene that may increase the risk of schizophrenia.

The National Institute of Mental Health estimates that a little over 1 percent of the U.S. adult population has schizophrenia--an illness that's categorized as a chronic, severe and disabling mental disorder brought about by deficits in thought processes, perceptions and emotional responsiveness, with symptoms for most beginning between the ages of 16 and 30.

Researchers from the Broad Institute, Harvard Medical School and Boston Children's Hospital found that an individual's risk of schizophrenia dramatically increases if they inherit gene C4. Previous research supported genetic evidence that an individual's risk of schizophrenia was located within a region of DNA found on chromosome 6. This study also focused on a region of the brain called the complement component 4 or C4 that's involved in the immune system. The gene is involved in "synaptic pruning," or a healthy reduction that occurs with brain cell connections that are no longer needed during adolescence.

As the brain develops, there are too many connections and synapses produced, according to Dr. Monsheel Sodhi, a professor at the Center for Biomolecular Sciences at the University of Illinois Chicago, who was not involved in the study.

"This kind of editing or pruning during adolescence and young adulthood occurs and is considered to be a fine-tuning of the brain for optimal function," Sodhi told Science World Report, noting that excessive pruning could result in symptoms of the illness. This also may explain why the first signs of schizophrenia start for many patients in their teen years. 

During the study, researchers analyzed the genomes of about 65,000 individuals and studied 700 postmortem brains--including information on the C4 gene in about 29,000 people with schizophrenia and about 36,000 people without the health issue in 22 countries. Findings showed that an individual with higher levels of C4 activity had a greater risk of developing schizophrenia. The same findings were true when researchers completed experiments on mice; they found that the more C4 activity there was, the more synapses were pruned during brain development.

"C4 genes seem to be elevated in the brains of schizophrenia patients, and the function of C4 genes is to prune or eliminate synapses," said Sodhi. "This would predict that schizophrenia patients also have a higher level of synaptic elimination during the late stages of brain development."

For future studies, researchers hope to focus on suppressing the gene pathway that's linked to the health problem--potentially preventing the illness from taking place during the teen years with targeted antipsychotic medications. However, Sodhi notes that's it's too soon to tell if this discovery might lead to new treatments.

"While the authors reported that complement C4 reduced synaptic density in mice, they did not report any behavioral testing in the animals," said Sodhi.

Schizophrenia currently has no known cure. However, there are various treatments, ranging from antipsychotic medications to different types of therapy that focus on coping with stress, relapses and warning signs, improving communication and social skills, support and education in families dealing with schizophrenia and vocational rehabilitation and supported employement that helps people with schizophrenia prepare for, find and keep jobs.

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