Why EVERYONE Over 40 Forgets Their PIN Number

Losing your keys, popping upstairs to get something, then forgetting what it was - we all have memory lapses, but are our 'senior moments' really due to advancing age? Here TANITH CAREY reveals the fascinating truth about how your memory changes through life...

YOUR 20s: Technology's already making you forgetful

After the dramatic growth spurts of your childhood and teenage years, by the age of 25 your brain has hit peak performance. 

It’s also at its heaviest — around 3lb — and the different parts are intricately wired up, making it the best it will ever be at storing, cross-referencing and recalling information.

As a result, twentysomethings perform better than any other age group at remembering the names of new people, recalling phone numbers and holding numbers in their heads long enough to do mental arithmetic.

Even so, one in seven still believes they have trouble remembering things. 

Studies are finding that young people are becoming increasingly forgetful, often because they are trying to do too much at the same time.

A study by researchers at the University of California found that using mobile phones, computers and other gadgets at the same time prevents you processing and storing information properly.

Scans reveal that this may be because the hippocampus, a part of the brain vital for forming new memories, is used less when people are distracted.

And all adults, regardless of age, forget things from time to time.

In a recent study of healthy adults, the average number of memory slips, such as putting the coffee jar in the fridge, was around six per week, irrespective of age, gender and intelligence.

YOUR 30s: Now it's baby brain

Your face may still look youthful at 30 but the brain’s ability to remember things is already declining.

This is due to falling levels of the chemicals that relay messages between your brain cells, which is part of the normal ageing process.

Your brain is now also shrinking at a rate of about two per cent every decade, as cells die away in the pre-frontal cortex, an area important for forming new memories and learning.

That means a new skill or foreign language may take longer to learn — and remembering the names of people to whom you have just been introduced is probably a little more difficult.

As this is the age when most women will start families, they may also be hit by ‘baby brain’, which scientists believe is a genuine phenomenon.

It’s thought the surge of hormones that comes with pregnancy, birth and breastfeeding — especially the ‘bonding hormone’ oxytocin, which has been found to numb the memory — makes new mums more absent-minded.

In one study, researchers at the University of Bradford set out to test the memory needed to remember things such as where you left your keys or parked your car.

When they compared a group of women who were pregnant with a group who were not, they found the mums-to-be did much worse on memory tests — and were just as forgetful three months after they had their babies and their hormone levels returned to normal.

However, it seems there are compensations. This week an analysis of data published in New Scientist magazine concluded that while motherhood may make new mums more scatterbrained, it also primes the brain for empathy, reasoning and judgement, so they can better protect and look after their infants.

YOUR 40s: Have I got alzeimer's?

Have you ever stood in line at the cash point, only to forget your PIN when you reach the front? Embarrassing as this may be, it isn’t a sign of approaching dementia. You are just normal for your age.

A study by the Mayo Clinic in the U.S. of more than 1,200 people between the ages of 30 and 95 found that almost all us have experienced declining memory by the age of 40.

The most likely reason is that the hippocampus, a horseshoe-shaped lobe close to the middle of the brain, slowly shrinks from the age of 30 through to the mid-60s.

There is also a loss of nerve connections stretching between brain cells, which means that while information is still locked inside your skull, it takes longer to retrieve.

By this age you are likely to have so many memories stored in your brain that retrieving them is like trying to find the right book in a vast library.

It’s at this age that people increasingly start to worry they are showing signs of Alzheimer’s.

Figures from the Royal College of Physicians show a four-fold increase in the number of patients worried they have degenerative brain diseases, even though tests find that most are simply absent-minded.

So why do so many fortysomethings find it difficult to remember simple facts?