Am I normal for my age? Vivienne Parry examines our perceptions and the realities of what happens to us as we get older. She unpicks the differences between ageing and disease and asks if there is such a thing as normal ageing.

It happens to us all; nothing can hold back the tide of time. The natural process of ageing not only affects our appearance and how our bodies respond to general wear and tear, but also how we succumb to and are affected by illness. Yet it seems, no one ages in the same way. Middle age for some of us doesn't end until we're well into our 70s, whereas some people feel old before their time.

The programme asks what will happen to us when we age normally? And indeed is there such a thing as a normal ageing process? Genes, lifestyle choices, environment and even social class all play a part.

So what was normal 20 or 30 years ago is not normal now. The average age of the world's population is increasing at an unprecedented rate. It's been estimated that the number of people worldwide who are 65 and older now will double by 2040 (from seven to fourteen per cent).

How we are ageing is changing too. We are living longer and dying quicker. Professor of geriatric medicine Raymond Tallis says that, 'Despite the fact that we're living longer, the period of chronic illness or disability before death is shrinking.' Advances in modern medicine have postponed many diseases of old age to such an extent that we live longer, healthier lives before succumbing when we are really old and frail and therefore die relatively quickly.

But not everyone is still running marathons at 75 or constantly feels 15 years younger than their actual age. And the phrase 'you're only as old as you feel' can be pretty depressing to some people. So what is normal for a certain age? How can we measure it? And does it really matter? Show less