Scientists have created the world’s first schizophrenic mice in an attempt to gain a better understanding of the illness.

It is believed to be the first time an animal has been genetically engineered to have a mental illness. Until now they have been bred only for research into physical conditions such as heart disease. It will allow researchers to study the disease and develop treatments using a limitless supply of laboratory animals.

Animal rights campaigners have condemned the research, saying that it is morally repugnant to create an animal doomed to mental suffering.

The mice were created by modifying their DNA to mimic a mutant gene first found in a Scottish family with a high incidence of schizophrenia, which affects about one in every 100 people. The mice’s brains were found to have features similar to those of humans with schizophrenia, such as depression and hyperactivity.

“These mutant mice may provide an important new tool for further study of the combinations of factors that underlie mental illnesses like schizophrenia and mood disorders,” said Takatoshi Hikida, of Johns Hopkins University in Baltimore, a leading researcher.

The egg cells of mice were genetically modified by inserting a gene associated with schizophrenia into their DNA. The eggs were fertilized and grown into viable baby mice using surrogate mothers.

Animal Aid, a campaign group, said rodents were not a reliable way of modelling human disease.