Eating less may keep the mind young, according to Italian scientists who reported on Monday they have discovered the molecular process by which a strict diet may save the brain from the ravages of age.

The research, published in the US journal the Proceedings of the National Academy of Sciences, is based on a study of mice that were fed a diet of about 70 per cent of the food they normally consumed.

Scientists found the calorie-restricted diet triggered a protein molecule, CREB1 that activates a host of genes linked to longevity and good brain function.

"Our hope is to find a way to activate CREB1, for example through new drugs, so to keep the brain young without the need of a strict diet," says lead author Giovambattista Pani, researcher at the Institute of General Pathology, Faculty of Medicine at the Catholic University of Sacred Heart in Rome.

Researchers have previously discovered that mice on diets showed better cognitive abilities and memory, less aggression, and tended to avoid or delay Alzheimer's disease. But they have not known exactly why.

"CREB1 is known to regulate (such) important brain functions as memory, learning and anxiety control, and its activity is reduced or physiologically compromised by aging," the study says.

Mice that were genetically altered to lack CREB1 showed none of the same memory benefits if they were on a low-calorie diet as mice that had the molecule, and showed the same brain disabilities as mice that were overfed.

"Thus, our findings identify for the first time an important mediator of the effects of diet on the brain," Pani says.

"This discovery has important implications to develop future therapies to keep our brain young and prevent brain degeneration and the aging process."