When our memory is affected by the ageing process, some people's brains compensate to stay sharp. Now, scientists want to find how those brains do that so that they can help everyone else stay sharp.

New research is showing that memory and other brain functions decline even in otherwise healthy people as they age, as anyone who habitually misplaces car keys have suspected. This is not Alzheimer's disease but the process of wear and tear in the brains due to normal ageing.

If you are 65 years old today, chances are good that you will continue to live to 83 and beyond. A new problem arises. How do you protect the brain from the ravages of time? A very important question as the population greys and improvements in healthcare means people who are 50 today are expected to live for another 40 years.

"I don't think we've recognised, as scientists or a society, (that) this is the front-and-center public health issue we face as a nation." Dr Denise Park, director of the University of Illinois' Center for Healthy Minds, told fellow brain specialists assembled by the United States government recently. "We need to understand how to defer normal cognitive ageing, the way we've invested in fighting heart disease and cancer.".

There are intriguing clues, gleaned from discoveries that some older people's brains literally work around ageing's damage, making new pathways when old ones disintegrates.

"It's not just fanciful or pie-in-the-sky" to try harnessing that ability, said Dr Richard Hodes, director of the National Institute on Aging, which organized the meeting to seek advice on the most promising research.

On top of the list that scientist have found has work for memory and mental sharpness is simple physical exercise. It appears to be as good for the brain as it is good for the body. Other options that have yielded promising results include brain-training games to medications that may keep brain networks better connected.

For older folks who worry about periodic memory lapses and what constitutes normal mental ageing and what is impending Alzheimer's, Science cannot yet tell for sure. But there seems to be a distinct difference.

A healthy brain is a bushy one. Branchlike tentacles extend from the ends of brain cells, enabling them to communicate with each other. The more you learn, the more those connections form. Alzheimer's kills neurons, so the cells disappear along with connections their neighbours need. According to Dr Carol Barnes of the University of Arizona, with normal ageing, the cells do not die but their bushes can shrivel to skinny twigs. Cells that are less connected have a harder time sending messages. Moreover, Alzheimer's seems to target first a different spot in the hippocampus, the brain's memory centre, from where ageing does.

There are two fronts that we can fight back.

Some brains are capable of withstanding a lot of punishment from Alzheimer's but the patients show little tell-tale signs of it's symptoms. This is known as "cognitive reserve" and autopsy studies have found between 20 and 40 percent of elders who displayed no confusion actually had brains riddled with Alzheimer's trademark plagues.

Brain scans show younger people tend to use different neural networks than older people when performing the same task. Compensation is how the brain adapts when old pathways can no longer function, to reroute itself and use an alternative route.

Scientist agree that physical exercise is the best proven remedy to stave off the ageing process. In fact when 70-year olds started a walking programme three days a week, and sophisticated scans showed their brains' activity patterns started resembling those of younger people.

It has also been shown that people with higher education, more challenging occupations and enriched social lives build more cognitive reserve than couch potatoes. This is what is known as the "use-it-or-lose-it" theory.

What about medication? Scientists are studying if an old blood pressure drug called guanfacine can work for children with attention deficit disorder. It works in the same brain region, the prefrontal cortex, where elder brains forge new networks. "If it works in a six-year-old, we hope it will work in the elderly", said Yale University neurobiologist Amy Arnsten.

But why wait for the results to be out, you can start training your brain today. You can start by doing more crossword puzzles, learning a new foreign language, a new skill or hobby, play mahjong, learn new memory skills and technques or master memory training. And always keep the mind active. And remember to keep physcially active as well.