A landmark study described as a "turning point" in tackling mental illness has lifted the lid on the biological cause of schizophrenia, according to Mirror.

For the first time scientists have linked the devastating disease to a physical process, the "pruning" of unwanted connections between brain neurons.

They hope the discovery will lead to more effective treatments targeting the disorder's roots rather than its symptoms.

During adolescence, the brain undergoes widespread re-wiring that involves "synaptic pruning".

The new study, based on a genetic analysis of nearly 65,000 people from around the world, pinpointed a defective gene that appears to trigger excessive pruning.

Scientists believe it is this that underlies the symptoms of schizophrenia , a severe psychotic condition marked by a loosening grip on reality, delusions, paranoia and hallucinations.

Lead researcher Dr Steven McCarroll, from Harvard Medical School in the US, said: "Since schizophrenia was first described over a century ago, its underlying biology has been a black box, in part because it has been virtually impossible to model the disorder in cells or animals.

"The human genome is providing a powerful new way in to this disease.

"Understanding these genetic effects on risk is a way of prying open that black box, peering inside, and starting to see actual biological mechanisms."

The gene, complement component 4 (C4), plays an important role in the immune system, marking infectious microbes out for destruction.

Because of this, initial genetic analysis suggested the possibility that schizophrenia might be triggered by an infectious agent.

AZERTAC