Obese people twice as likely to get Alzheimer's

Britain's obesity explosion could trigger a second even more serious epidemic - of dementia. Experts warned yesterday that our fondness for fast food and resistance to exercise was not only causing waistlines to bulge - it is also damaging our brains.

An estimated 700,000 people have dementia in the UK and the number is forecast to rise to as many as 1.5 million over the next 50 years, according to the Alzheimer's Society.

But if the population goes on getting fatter, the total could rise to 2.5 million, said Clive Ballard, director of research at the society. "Obesity is a huge risk factor," he said. "People who are overweight at 60 are twice as likely to get dementia at 75. We have a public health epidemic of dementia given the ageing of the population, and it is essential to reduce the risks. If these factors are not controlled, it may not be 1.5 million but 2 or 2.5 million people affected."

Currently one in 20 people aged over 65 has signs of dementia, rising to one in five over 80. Increasing obesity could double the incidence among over-65s to one in 10, said Mr Ballard.

The mechanism of how obesity affects the brain was unclear but it encompassed diet, exercise and physiological effects. Research has shown that people who eat a diet rich in fruit and vegetables have an up to 40 per cent reduced risk of developing dementia. Exercise has a similar effect.

Studies also suggested that amyloid protein which can build up in the brain, causing damage to nerve cells, is cleared from the blood more efficiently when cholesterol levels are low. High cholesterol could increase build-up of the protein and hasten the onset of Alzheimer's. Neil Hunt, chief executive of the Alzheimer's Society, said: "I remain genuinely mystified why this is still such a low priority. The cost of dementia to individuals, families and the state is £17bn a year. Now there is research suggesting dementia is not as inevitable as we thought. There is no cure but evidence is building that lifestyle choices make a difference to risk."

Launching a booklet, Be Headstrong, he said that five steps were necessary to reduce the risks - do not smoke, eat less saturated fat, exercise regularly, lead an active social life and have blood pressure and cholesterol checked regularly. "If we could delay the incidence of dementia by five years we could reduce its incidence by 50 per cent," he said.

Professor Jeremy Pearson, associate medical director of the British Heart Foundation, said risk factors for heart disease were also risk factors for dementia. "We now know that protecting the heart will also protect the brain," he said. "Treatments that reduce heart disease also reduce dementia. There are very similar pathological processes underlying both."

Tony Rudd, consultant stroke physician at Guy's and St Thomas NHS Trust, said up to one-third of the over-65s who had a stroke would develop dementia within three months. "Public health initiatives to prevent stroke and related risks are essential," he said.

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