From: Guardian

Walking may protect the brain against shrinking and preserve memory in the elderly, according to research by US neurologists who monitored 300 volunteers over 13 years. …

The US study bears this out, with neurological tests on dementia-free people in Pittsburgh who agreed to log their walks and accept brain monitoring in 1995.

Tests nine years later, followed by a further round in 2008, showed that those who walked the most cut their risk of developing memory problems by half.

The study suggest that nine miles a week – or in the urban US terms of the data, 72 Pittsburgh city blocks – is the optimum distance for “neurological exercise”.

The paper, published in Neurology, the online medical journal of the American Academy of Neurology, found no discernible bonus in going the extra mile after that.

The first round of scans showed that nine-mile walkers had larger brains than those who walked around for less.

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