Christine Webber's mother suffered from Alzheimer's so she has more reason than most to investigate brain health

I went to my GP recently for a pneumonia jab and while I was in the waiting room, I heard two other patients discussing dementia.

"How do you prevent it?" one of them said. "That's what I'd like to know."

Wouldn't we all?

My mother had Alzheimer's for 15 years, and for the last five of those had no knowledge of who she was, let alone anyone else. As a result, I'll give anything a go which might prevent it happening to me.

In 2010, not long after she died, I was commissioned to write a book on positive ageing called Too Young to Get Old. Initially, I focused on the body and fitness, but soon became fascinated by new research about brain health.

Prior to that, I'd written articles on keeping the brain in shape, and had quoted various experts as saying that we should do a crossword or sudoku daily, learn a language or a musical instrument, and also try performing routine tasks differently - like tackling the ironing with the 'wrong' hand.

But what I learned when I was working on my book was that the advice was changing, and many experts were now saying that the best thing for the brain was for its owner to be physically active.

At first, I was quite sceptical because, like lots of people, I'd tended to regard the brain as a separate entity from the rest of the body.

But when you think about it, it depends on the same supply of blood and oxygen as all our other organs, so it makes sense that anything which keeps us physically fit is also going to help our brains.

One of the most interesting books I came across during my research was Spark! by Professor John J Ratey from Harvard, which is all about exercise and the brain. The entire 294 pages are well worth reading, but the segment that leapt out at me was a report of a small study of previously inactive pensioners.

This is what happened. Firstly, they were given medicals, and also MRI scans of their brains. Then, they were randomly divided into two groups.

The first group were encouraged to do stretching exercises for one hour, three days a week for six months. At the same time, the second group walked briskly on treadmills. At the end of this experiment, all participants were tested again.

As you might imagine, the individuals who had done all that brisk walking improved their fitness levels.

But the big surprise was in the results of the MRI scans, because the brains of these more active people had increased in volume in those parts of the organ that govern thinking, decision-making and memory. In simple terms, their brains looked younger than they had six months previously.

Since then, there have been many other studies which have led scientists and medics to believe that exercise not only slows cognitive decline but can actually reverse some of the deterioration associated with ageing. This is significant news because, according to Alzheimer's Research UK:

One in every three babies born in this country this year will develop dementia

In 2025, there will be one million people in the UK with dementia

By 2050, there will be two million.

Obviously, there's a lot of hope and expectation that new drugs will, in time, work miracles. But meanwhile, it seems to me it's well worth putting this research into practice and getting sportier.

So, what can we do?

1. Remember that any kind of physical activity that helps the heart, will also boost the brain

2. If you've been very inactive, do begin slowly, but gradually aim to do 30 minutes of moderate exercise, five days a week

3. Exercise in ways you enjoy so that you've got a better chance of sticking at it.

You've probably got some great ideas of your own about becoming fitter. But if you haven't, make a start with some walking, and get into the habit of doing it as fast as you can.

Cycling is good too. As is kicking a ball around in the park with your children or grandchildren. And activities which combine movement with thinking and decision making - such as playing tennis, or dance classes - look as if they might be extra beneficial.

If you become more active, you should notice an increase in your fitness, balance and energy levels. You'll probably sleep better too and feel happier much of the time. Most importantly of all, you could soon become aware that your mind is sharper and clearer, and that your memory is more reliable.

So, getting fitter really does seem to spark up our little grey cells - and knowing that, is all the encouragement I need to dust off my dancing shoes!