Playing chess in old age and going jogging or swimming could be the best preventative measures against the development of the degenerative Alzheimer's disease that affects one in 14 people aged 65 or over.
Along with five other factors – controlling weight, blood pressure and diabetes, avoiding depression and quitting smoking – keeping mentally and physically fit could dramatically cut the incidence of dementia, which is becoming a major human and financial burden around the globe. Mental and physical exercise are most important because they influence the others, by keeping weight and blood pressure down, reducing the risk of diabetes and depression.
People who can do all this and avoid smoking substantially reduce their risk of developing Alzheimer's. Worldwide, an estimated 33.9 million people have the condition and that number is expected to triple in the next 40 years.
In the UK, an estimated 500,000 people are affected, with one in six over-80s succumbing to the disease that strips sufferers of their dignity and personality.
A review of research presented at the International Conference on Alzheimer's Disease in Paris yesterday, and published in the medical journal The Lancet, concluded that up to half of all Alzheimer's cases worldwide are potentially attributable to the seven preventable risk factors. Of these, low education and lack of mental stimulation in old age are considered to be the most significant.
Deborah Barnes and Kristine Yaffe, of the University of California at San Francisco, who wrote the review, say that education and mental stimulation throughout life are believed to reduce the risk of Alzheimer's and dementia "by helping to build a cognitive reserve that enables individuals to continue functioning at a normal level despite experiencing neurodegenerative changes".
Post-mortem examinations have shown that people who were mentally active throughout their lives, with no sign of the symptoms of Alzheimer's disease, nevertheless had the same degeneration of the brain seen in those who suffered serious dementia while alive. The implication is that the despite this neuro-degeneration, mentally active people manage to stave off the symptoms of Alzheimer's.
Overall, the researchers estimate that the seven factors potentially contribute to more than 17 million cases of Alzheimer's worldwide, or 250,000 in Britain. A 25 per cent reduction in all seven risk factors could prevent as many as three million cases.
In a report on the study, Laura Fratiglioni, of the Karolinska Institute in Sweden, said none of the seven factors were proven to cause Alzheimer's but that "accumulated evidence from epidemiological research strongly supports a role for lifestyle and cardiovascular risk factors." Large-scale trials to change these risk factors in populations at high risk, as has been done for heart disease, should now be implemented, she added.
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