Memory When asked to memorise a list of 75 words read out five times, the average 18-year-old scores 54, the 45-year-old 47 and the 65-year old just 37.
Brain cells
"This is not because brain cells die," says Dr David Weeks, consultant clinical neuro-psychologist at The Royal Edinburgh Hospital.
"We do lose brain cells at a rate of up to 10,000 per day after about the age of 40, but the majority of memory problems associated with age are caused by poor concentration or motivation or by anxiety and stress."
Sandra File, professor of psycho-pharmacology at King's College, London, agrees that stress can affect memory, but, she says, "As we grow older our circulation tends to slow down which means less oxygen reaching our brain cells. We also don't stretch our brains as much as we used to.
"The memory is like any other muscle. It needs to be used to function at optimum levels. There is a lot of truth in the old adage: Use it or lose it," she explains.
Like Professor File, Dr Weeks believes regular exercise is key to keeping your memory in good shape.
Exercising for half an hour at least three times a week will help to keep you on the ball, according to research carried out at the Duke University Medical Centre in North Carolina.
Exercise gets the circulation going which also results in an improved blood flow to the brain.
Food for thought
It is also thought that eating certain nutrients can significantly boost concentration, attention span and memory, and more recent research suggests supplementing your diet could also help boost memory skills.
Exciting new research headed up by Professor File shows that isoflavones, the natural plant oestrogens found in soya foods, might act on oestrogen receptors in the human brain, particularly those in the hippocampus, a crucial area for memory.
In a recent study carried out on 18- to 34-year-olds, a soya-rich diet improved memory and mental flexibility (the ability to adapt to new situations) after just 10 weeks.
Menopausal women given soya isoflavones in capsule form benefited similarly. Good sources of soya include tofu, soya beans and soya milk.
Foods rich in the antioxidant vitamins A, C and E are particularly good for brain health and memory.
They help to mop up free radicals, rogue molecules which can cause extensive cell damage in the body, including the brain. Good sources include richly coloured vegetables such as bananas, red peppers, spinach and oranges.
It's also a good idea to eat plenty of oily fish which is rich in omega-3 fatty acids as well as folic acid - all of which are vital for the smooth functioning of the brain and nervous system. Good sources include sardines, salmon, herring and mackerel.
Ginkgo biloba, a herbal extract made from the leaves of a Chinese plant known as the 'tree of memory' is the best researched memory-boosting supplement.
Several clinical studies carried out at the University of Surrey show that it enhances all types of cerebral insufficiency, especially verbal memory impairment. It works by improving circulation which, in its turn, increases blood flow, carrying more nutrients and oxygen to the brain.
Stay sharp
Many studies show that the stimulation is the key to good memory as we age. People who take part in lots of different types of activities have better powers of recall.
The secret to good memory is activity and diversity, says Dr Weeks. The more active your brain is, the better your memory is likely to be, and the more different ways you use your mind, the easier you'll find remembering.
It's all to do with being active rather than passive: whether you actively concentrate and focus on things or whether you just let them wash over you. Try the following exercises to sharpen up your mental faculties:
- Playing games for health
- Do a mental exercise every day - crossword, word search or quiz. If you don't know an answer, look it up then try to remember it the next day.
- When doing your finances, ditch the calculator - use your brain to work them out.
- Take up new activities - gardening, knitting, anything active involving brain, eye and hand co ordination.
- Make shopping lists then memorise them before going to the shops.
- Engage in activities that stretch your brain such as chess, bridge or anything that pushes you mentally that little bit further.
- Work for as long as you can, keep up with your friends and join local social groups. Studies have shown that those who maintain social contact, especially at work, fare significantly better in memory and concentration tests.