New York: "The elderly can delay the onset of Alzheimer's disease by keeping their mind active," says a new study. 

Frank LaFerla, a professor of neurobiology and behaviour at the University of California at Irvine, studied hundreds of mice between two and 18 months of age that were bred to develop the plaques and tangles characteristic of the disease, reported health portal News Medical.

Mice in one group were made to swim in a round tank of water until they found a submerged platform on which to stand. The mice were trained four times a day for one week at two, six, nine, 12, 15 and 18 months of age, and were evaluated at each session for learning and memory abilities.

Other groups of untrained mice were allowed to swim in the tank for just one session before their learning and memory skills were tested and their brains examined for plaques and tangles.

Mice up to 12 months of age that learned on previous occasions had fewer plaques and tangles in their brains, and they learned and remembered the location of the escape platform much better than mice not previously allowed to learn.

At the 12-month point, the mice that had learned developed levels of beta amyloid and hyperphosphorylated-tau that were 60 percent less than the mice that had not learned.

But by 15 months of age, the mice that had learned deteriorated and were identical both physically and cognitively to the mice that had not learned.

"We were surprised this mild learning had such big effect at reducing Alzheimer's disease pathology and cognitive decline, but the effects were not strong enough to overcome later and more severe pathology," a researcher said.

The study with genetically modified mice is the first to show that short but repeated learning sessions can slow a process known for causing the protein beta amyloid to clump in the brain and form plaques, which disrupt communication between cells and lead to symptoms of Alzheimer's disease.

The researchers are now investigating if more frequent and vigorous learning will have bigger and longer benefits to Alzheimer's disease.