Brain study suggests exercise may protect the mind from Alzheimer's

• Exercise helps to flush a toxic molecule from the brain and causes a beneficial one to move in and protect nerve cells, research on mice shows.
• "Our experiments support the idea that exercise is a good approach to all types of problems in the brain and that a sedentary lifestyle is a risk factor," says Ignacio Torres-Aleman, who led the study at the Cajal Institute in Madrid.
• Torres-Aleman and his colleagues were intrigued by previous studies showing that exercise slows mental decline in mice engineered to mimic Alzheimer's disease.
• They found that exercise doubled the levels of a protein that helps to flush molecules thought to underlie Alzheimer's disease out of the mice's brains and into their blood.
• The protein, called megalin, ejects a potentially destructive protein called amyloid-beta.
• Megalin also binds to a beneficial molecule in the blood, called insulin-like growth factor, and transports it to the brain.
• The findings appear in the Journal of Neuroscience1.
• Paul Adlard, a neuroscientist at the University of California, Irvine, has looked at the brains of mice in a different model of Alzheimer's disease.
• His data, although only preliminary, suggest that exercise does not boost levels of the protective insulin-like growth factor.
• Adlard says that the findings of Torres-Aleman and his colleagues are "tantalizing", but that more study is needed.
• The findings, he says, open the door to developing drugs that could boost levels of the megalin shuttle and help keep the brain healthy.
• Mattson notes that the link between exercise and brain health is still not certain in humans, although the evidence is mounting up.
• Other research has found that staying mentally agile or even maintaining a slim physique may help to protect against Alzheimer's and other brain disorders.