Brain Circuit Problem May Cause the 'Voices' in Schizophrenia

Scientists may have just found out what causes the "voices" in schizophrenia. They've identified problems in a connection between brain structures that may predispose individuals to hearing the "voices" that are a common symptom of schizophrenia.

In order to learn a bit more about the underlying brain circuitry that might cause a person to hear voices, the researchers examined a mouse model of the human genetic disorder 22q11 deletion syndrome. This syndrome occurs when part of chromosome 22 is deleted and individuals are left with one rather than two copies of about 25 genes. About 30 percent of people with this syndrome develop schizophrenia, which made it a good place to start to learn more about the conditions.

In any earlier study, scientists linked one of the lost genes, Dgcr8 to brain changes in mice with the deletion syndrome that affect a structure important for learning and memory. During this study, the researchers examined Dgcr8 and linked the loss of the gene to changes that affect a different brain structure, the auditory thalamus. Researchers have known for years that antipsychotic drugs bind to a protein named D2 dopamine receptor (Drd2). Yet until now, how this quieted the "voices" of schizophrenia was unclear.

In the end, the scientists found that Drd2 levels were elevated in the auditory thalamus of mice with the deletion, but not in other brain regions. When the researchers looked more closely at the missing 22q11 genes, they also found that mice that lacked the Dgcr8 responded to a loud noise in a similar manner as schizophrenia patients.

"We think that reducing the flow of information between these two brain structures that play a central role in processing auditory information sets the stage for stress or other factors to come along and trigger the 'voices' that are the most common psychotic symptom of schizophrenia," said Stanislav Zakharenko, one of the researchers, in a news release. "These findings also integrate several competing models regarding changes in the brain that lead to this complex disorder."

The findings reveal a bit more about schizophrenia. This could help develop future treatments for the conditions which could help patients in the future.

The findings are published in the journal Science.