In order keep those marbles in later life, Ian Robertson, a neuroscientist from Trinity College, Dublin, says exercise, diet, lifestyle and intellectual outlook will counteract the decline in mental capacity that accompanies ageing.

Robertson says there is strong evidence that the degree to which mental faculties are maintained, depends on a number of simple environmental and behavioural factors.

He has identified seven factors - aerobic fitness, a stimulating job, a good education and willingness to keep learning, a minimum of stress, friends and a good social life, a diet rich in oily fish, fruit and vegetables, and the ability to think young.

Dr Robertson says that it is known that optimists live longer than pessimists, and that optimism and mood has effects on the immune system which is tied in with brain function.

If a person thinks they are old at the age of 60 then they will behave as old, says Dr Robertson.

FBI funds designated for investigating fraud in health care also seem to have shifted to other purposes, including fighting terrorism, and military funds for cleaning up polluted sites and meeting clean air standards have been proposed for capping and exemption by the Pentagon.

These observations are not intended to diminish the tragedies of 11 September 2001 or 7 July 2005 or other terrorist actions, nor to negate the importance of developing effective ways of making sure such tragedies are not repeated, says the author.

It is certainly justifiable for governments to appropriate substantial funds to prevent potential future threats to our security. But public funding for current threats should not be compromised.

"Predictable tragedies happen every day. We know strategies to reduce deaths from tobacco, alcohol, poor diet, unintentional injuries, and other predictable causes. And we know that millions of people will die unless we protect the population against these routine causes of death," she concludes.

bmj