Aussie researchers boost elderly mice's brain power with exercise

Australian neuroscientists have discovered an exercise "sweet spot" that could reverse the cognitive decline in aging mice, paving the way for human studies.

After more than a decade of testing, researchers from the University of Queensland led by Queensland Brain Institute Emeritus Professor Perry Bartlett and Dr Daniel Blackmore, found 35 days of voluntary physical exercise improved the mice's learning and memory abilities.

Blackmore told Xinhua on Tuesday that the mice had lived sedentary lives for two years in cages without running wheels, and then they were allowed to use the running wheels whenever they liked.

"Mice love to move, and they would run for one or two kilometers, usually at night, which we then recorded. We then tested their cognitive ability following defined periods of exercise and found the optimal period that greatly improved their spatial learning."

The researchers used Magnetic Resonance Imaging (MRI) to examine how the production of new neurons changed the brain's circuitry and improved the mice's learning abilities.

"Using MRI, we were able to study the brain following exercise and for the first time identify the critical changes in the structure and functional circuitry of the hippocampus – the region of the brain critically important to learning and memory," Blackmore said.

"We found that growth hormone (GH) levels peaked during this time, and we've been able to demonstrate that artificially raising GH in sedentary mice was also effective in improving their cognitive skills."

The researchers said it is an important discovery for the thousands of Australians who are diagnosed with dementia every year, with the disease being the nation's second leading cause of death.

The research, which was published in two separate papers in iScience, provides further proof that loss of cognitive function in old age is directly related to the diminished production of new neurons and underlines the importance of being able to activate neurogenic stem cells in the brain.

"The next stage is to determine their sweet spot and which circulating blood factors, such as GH, can be used as a biomarker for when this is achieved," Blackmore said.