Schizophrenia: Gene discovery indicates risk and cause

Researchers have discovered gene mutations that indicate a person's risk of developing schizophrenia and its causes. This may help improve drug treatments.

Schizophrenia is a serious mental condition, characterized by hallucinations, periods of psychosis and a detachment from reality. The World Health Organization ( WHO) estimates that schizophrenia affects about one in 300 people worldwide.

But we don't really know what happens in the brain to cause it.

"Our knowledge about schizophrenia is close to zero," says Stephan Ripke, a researcher at Berlin's Charitie university hospital.

Ripke is a co-author on one of two new research papers on schizophrenia published in the science journal Nature.

Two international teams of researchers have discovered gene mutations which they say strongly influence a person's likelihood of developing schizophrenia, and 120 genes that could play a role.

It is fundamental research that is unlikely to have an immediate impact for people living with schizophrenia. But the researchers say their findings could lead to better medication for schizophrenia in the near future.

New medicines for schizophrenia

There are medicines for schizophrenia but they do not address the disorder's root cause. The drugs we use today tend to tone down the effects or symptoms of schizophrenia, but they do not treat or cure the condition.

The most common schizophrenia medication is called chlorpromazine.

Chlorpromazine was originally developed as an anesthetic, but then doctors found that it helped prevent hallucinations in psychiatric patients.

"It was just an incidental finding. It didn't come from psychiatric research," says Ripke.

But Ripke and the other scientists say this research could help develop medication that specifically targets the root of the problem. Their results could also help determine a person's risk of developing schizophrenia.

The human genome and schizophrenia

One of the two studies was conducted by the Psychiatric Genomics Consortium (PGC) at the UK's Cardiff University, which investigated the entire human genome, looking for genetic variations that increase a person's risk of developing schizophrenia.

They analyzed genetic information from 77,000 people with schizophrenia and 244,000 people without it. They found nearly 300 regions of the genome that could be linked to a person's risk of developing schizophrenia. Within those regions, they discovered 120 genes that could play a role in causing the disorder.

The other study was conducted by the SCHEMA team, a joint effort led by the Broad Institute of MIT and Harvard Universities. The researchers discovered ten genes with rare mutations that appeared to increase a person's schizophrenia risk and 22 more that could play a role in that.

"[We all have] a one percent chance of developing schizophrenia," said Benjamin Neale, a SCHEMA co-author and member of PGC, in a press release. "But if you have one of these gene mutations, it becomes a 10, 20, even 50% chance."

The gene mutations help draw an early map of schizophrenia's origins in the brain.

What we still don't know about schizophrenia

Schizophrenia usually starts presenting in a person's late adolescent years or 20s.

In the past, researchers have studied the environmental aspect of the disease. For instance, they have found that where a person grows up, teenage cannabis use, or what their mother ate during pregnancy can increase their chance of developing schizophrenia.

Scientists have also known that schizophrenia is about 60 to 80% hereditary. But they have had little understanding of the genetics of the disease until now.

That's true for a number of mental illnesses, says Ripke, including bipolar disorder or borderline personality disorder. But there is a good reason for that.

For one, says Ripke, schizophrenia cannot be diagnosed through a blood test or even a brain scan.

Then, he says, there is no way of studying the disease in animals: "We only have questions and observations, and even the observations aren't enough if we don't [share a] common language."

We can't talk to them and they can't talk to us, says Ripke. "But we need to know if people have hallucinations, if they hear voices."

That means schizophrenia research has to be done on humans. But ethical concerns prevent scientists from collecting the samples they need to facilitate genetic analyses. Again, with good reason: "We can't just take brain cells from schizophrenia patients," Ripke says.

But it is possible, says Ripke, when people volunteer.

"Our study would have never worked without the trust of thousands and thousands of patients who gave us their genetic information," Ripke says. "We are so utterly thankful to all the people who trusted us with their data."

Schizophrenia often affects people in their late adolescence and their 20s