I ALWAYS had trouble believing the expression "life begins at 40". I remember more than one friend scrawling it on my card when I celebrated, or rather mourned, that particular anniversary.

From where I sat - as usual, too exhausted to stand - it didn't feel like a new start. It felt like another year notched up, another 12 months during which my energy levels certainly hadn't shot up.

If anything, I felt more weary. Not just physically, but mentally too. I was becoming more forgetful, more likely to leave things in odd places and much more prone to find myself driving the car in the opposite direction to the route I intended.

In the three years since then, things have progressed only one way - downhill.

So I was pleased to learn that, despite many claims to the contrary, the popular myth that life picks up at 40 is not true. The reality is, a study in America has found, that 40 is the age when the brain starts to deteriorate. As we get beyond that age, crucial genes involved in learning and remembering often become damaged as we enter our fifth decade.

The research by a professor at Boston Children's Hospital claims other genes involved in the body's ability to repair itself have to 'work harder' after 40 has been reached.

Thank goodness it is official. I have trouble in many areas because my mind and body have seen better days, mostly in the following areas:

Work

It may sound childish but I'm always whining to my younger (by at least ten years) colleagues: "You're loads faster than me. I can't write half as quickly as you do." This often develops into full-blown paranoia: "What have you done today? I bet you've done loads more than me." It definitely takes longer than it used to get my brain into gear. An 8am start doesn't help. When I'm at home with the children I have difficulty getting my head around the plot in Fimbles, let alone trying to decipher appalling shorthand.

Shopping

I've never been one for lists - far too organised for my liking - but now I find myself searching for a trolley with a little clipboard attached, so that I can tick off my bread, milk, baked beans, loo cleaner, corn flakes and 40-odd other items I regularly buy on the weekly big shop.

Worryingly, though, it is getting to the stage where I need to make a note even if I'm buying only one or two items, because I have been known to drive to Tesco for a jar of coffee and come home with a box of dishwasher tablets (that wouldn't be so bad if we had a dishwasher).

Appointments

Hair, dental, even visiting friends - it all has to be written down in thick black marker and left in prominent places around the house. 'Owe Sue £1' was stuck to my work bag at the weekend because however hard I try, some things just can't be stored and retrieved without regular reminders. And, because my dentist charges for missed appointments, it is definitely worth the Post-Its.

Staying power

Only last week I spent a rare night out with friends. We were saying goodbye to a friend who is moving to another part of the country, so I had gone to bed early the night before to make allowances. But even before 9pm I felt myself flagging and my mind wandering in the direction of the sofa in our living room and the jar of Ovaltine in the kitchen cupboard.

"I used to get ready to go out at this time," I said to another 40-something friend. Making superhuman efforts I did manage to stay until 10.30pm and even managed a cup of coffee (black - I needed it to stay awake) at my friend's house afterwards.

I think it is time allowances were made for us over 40s. A nice, big, fat early retirement package, cash towards a personal secretary and subsidised breaks at health farms. These things would surely be vote-winners.

Updated: 08:48 Tuesday, August 31, 2004