When it comes to ways we can boost our brain power and stop our "little grey cells" from degenerating as we age, regular exercise is the leading method.
And by a long stretch, too.
The latest evidence of how maintaining physical fitness will benefit your mental faculties comes from the Sunnybrook Research Institute and the University of Waterloo, in Ontario, Canada.
There the researchers have been digging around to discover conclusive proof that there is a link between exercise levels and the prevention of cognitive decline and age-related diseases such as dementia.
With many previous studies, scientists have had to rely on the testimony of the human "guinea pigs" taking part in trials to ascertain how much physical exercise they do or have done in the past. But such self-reporting is far from reliable, explains Laura Middleton, a researcher at the University of Waterloo.
"While self-reporting is good for capturing activities such as jogging or cycling or tennis - types of activities people are more inclined to record - it does a relatively poor job of capturing low-intensity activity such as walking or daily chores," says Middleton. "But these may also be important to the risk of cognitive impairment."
To find a more definite link, Middleton's team measured physical activity in their human test subjects by having them drink chemically labelled, but totally safe, water. Participants in the five-year study drank a small amount of this special water, and by measuring the isotope variants in their urine, the researchers could calculate each person's actual energy expenditure.
"We found there was a strong relationship between activity energy expenditure and the risk of cognitive impairment," Middleton explains. Those people who did more exercise - both planned and incidental - had as much as 90 per cent reduced risk of serious decline in brain function in later life, compared with those with very low energy activity expenditure.
This latest data certainly helps to cement the idea that an active body will help maintain the brain - and it's not the only academic evidence of this. At the same time the Canadian study was published, a similar piece of research from the Foundation of Public Health in Paris, France, revealed how women who recorded the equivalent of a brisk, half-hour walk every day also had a lower risk of cognitive impairment.
It is advice that all of us would be wise to adhere to. According to Alzheimer's Disease International (ADI), a non-profit research charity based in Europe, there are currently 30 million people with dementia in the world. But as life expectancy levels rise and science makes progress in combating infectious diseases, so the incidence of dementia and Alzheimer's will increase - by as much as 125 per cent in the Middle East over the next 40 years, according to the ADI.
The relationship between our diet and the shelf life of our minds is under increasing scrutiny by ADI researchers, too. There's a growing body of evidence to suggest that you can stay sharp and prevent long-term memory problems if you take care over how you feed your brain - especially when it comes to how much we eat.
Being overweight can raise your risk of developing diabetes - a disease that, according to research from the Rush University Medical Center in Chicago, can seriously increase your chances of contracting Alzheimer's disease. In a nine-year study of more than 800 people, researchers discovered that those with type 2 diabetes were 65 per cent more likely to suffer from severe cognitive decline than those without the fluctuating blood levels of insulin and glucose. A similar study carried out in 2010 at King's College London found that older people with mild memory loss are three times more likely to develop dementia if they have diabetes.
Exercising to keep your weight down can therefore have a double benefit for helping stave off the threat of mental declines, as can eating the right kinds of food.
"Too much saturated fat can cause narrowing of the arteries, making heart attack or stroke more likely and heart attacks, stroke and vascular disease increase a person's risk of developing vascular dementia," explains Professor Clive Ballard, the director of research at the UK's Alzheimer's Society. "But, equally, a number of research studies have shown that the polyunsaturated fatty acids found in oily fish might also help to protect the heart and blood vessels and lower the risk of mental decline in later life."
Fish and fatty acids are not the only foods with brain-protecting qualities either. Caffeine has been claimed, by some experts, to aid both immediate alertness and have long-term cerebral benefits. Regular coffee drinkers may have up to a 60 per cent lower risk of contracting Alzheimer's, according to one study from the European Journal of Neurology, which suggests caffeine keeps brain receptors active as we age.
"Various spices and herbs including curcumin, sage and lemon balm may also have a protective effect on the brain," adds Ballard. One test-tube study from the University of California found that curcumin - found in the spice turmeric - could help halt the destructive effects dementia has upon brain cells. "But, research is continuing and there is no conclusive evidence as yet," Ballard says.
Regular heart-boosting exercise and having a varied, healthy diet aren't the only ways to stave off the threat of dementia. Health professionals such as Ballard also recommend that we follow the "use it, don't lose it" approach too.
"Research has found that keeping the brain active seems to increase its vitality and may build its reserves of brain cells and connections," he says. Staying curious, reading, writing, learning new languages and doing crosswords and puzzles can all contribute to ensuring your memory stays sharp, even when physically you're no longer as quick as you once were.