Researchers have created a schizophrenic mouse, which will allow testing of new drugs and treatments before they are used on humans, said a study out Monday.

The scientists used genetic engineering to create mice whose brain structures and behavior are similar to the two million persons suffering from schizophrenia in the United States.

Previously, researchers could only induce the symptoms of schizophrenia, such as delusions, mood changes and paranoia, by administering drugs.

The new mouse will allow researchers to track the progression of the disease in mice, which parallels the human counterpart.

The mouse model was made possible by the recent discovery of a gene, DICS1, which produces a protein that helps nerve cells take their proper place in the brain. A person or a mouse without it is more prone to suffer schizophrenia, the study said.

The new mouse produces an incomplete, shortened version of the DISC1 protein, which interferes with the workings of the brain.

These mice matured with symptoms of schizophrenia. With magnetic resonance imaging, researchers confirmed that their brains shared the structures of schizophrenic mice.

Researcher Akira Sawa of Johns Hopkins University said the engineered mice were not as mentally ill as humans with the disease, because sufferers have more than one genetic defect.

"However, this mouse model will help us fill many gaps in schizophrenia research," Sawa said. "We can use them to explore how external factors like stress or viruses may worsen symptoms."

"The animals can also be bred with other strains of genetically engineered mice to try to pinpoint additional schizophrenia genes."

The paper’s authors are researchers at Johns Hopkins, in Baltimore, Maryland, and at the Tokyo University of Agriculture.