A new study finds that exercise produces a hormone that may improve memory and protect against Alzheimer's disease. The study was co-led by Ottavio Arancio, a researcher at Columbia University's Vagelos College of Physicians and Surgeons and Taub Institute for Research on Alzheimer's Disease and the Aging Brain.

An earlier study a few years back discovered a hormone called irisin that is released into the circulation during physical activity. And research found that the hormone may also promote neuronal growth in the brain's hippocampus. Speaking about it, Arancio said, "This raised the possibility that irisin may help explain why physical activity improves memory and play a protective role in brain disorders such as Alzheimer's disease."

Arancio and his colleagues looked for a link between irisin and Alzheimer's. Using tissue samples from brain banks, they found that irisin is present in the human hippocampus and that hippocampal levels of the hormone are reduced in individuals with Alzheimer's.

These experiments show that irisin, in mice, protects the brain's synapses and the animals' memory: When irisin was disabled in the hippocampus of healthy mice, synapses and memory weakened. Similarly, boosting brain levels of irisin improved both measures of brain health.

The researchers then looked at the effect of exercise on irisin and the brain. In the study's most compelling experiments, the researchers found that mice that swam nearly every day for five weeks did not develop memory impairment despite getting infusions of beta amyloid - the neuron-clogging, memoryrobbing protein implicated in Alzheimer's.

Blocking irisin with a drug completely eliminated the benefi ts of swimming, the researchers found. The fi ndings suggest that irisin could be exploited to fi nd a novel therapy for preventing or treating dementia in humans, Arancio says.

Source: indiatimes.com