When it comes to intellectual stimulation, bingo isn't the first game that leaps to mind. Chess or bridge, perhaps, but how much brain power can it take to match up the numbers being called with those on your card?

A lot, according to new research, which shows there's more to bingo than cash prizes and some small-talk between games.

Gwen Humphreys, 87, and Joyce Cobbs, 74, celebrate a win at Gala Bingo

When it comes to staying mentally agile, the UK's three million bingo players - many of them elderly - often have the edge.

A recent study found bingo players were faster and more accurate than non-bingo players on a range of tests measuring mental speed, the ability to scan one's environment for information and memory for previously seen items.

The news went down well at Gala Bingo in Acton, west London, where a handful of die-hard fans gathered several hours before the first session of the day to swap tips and gossip. All credit the game with keeping their minds active and their social diaries full.

Joyce Cobbs, 74, says her doctor compliments her on her reflexes. "I've been playing bingo for 30 years and it keeps me on the ball. It's far better than stagnating in front of the television."

Brain food

At a nearby table, Gwen Humphreys, a spry 87, lines up her bingo books and bananas - essential brain food for the coming session. "You have to be quick to play bingo, especially scanning the numbers to see if you've won." She regularly plays up to six games at once, and every so often pockets �500 in prize money.

All our customers are sharp as tacks - if I call a number wrong, they're on my case in a flash.

Alan Stockdale

Just as physical exercise keeps the body in shape, there is a "the use it or lose it" theory to mind activity.

"Age-related decline in mental abilities may be partially due to lack of use," says Julie Winstone, who carried out the research at the University of Southampton.

"It may be that keeping mentally active helps to maintain mental alertness. If that is the case, there could be a valid therapeutic reason for recommending bingo."

Cash prizes

The lure of big cash prizes keeps up the competitive spirit and means bingo players often stretch themselves to the limit.

A standard bingo card carries 15 numbers and players must match them to the ones being called.

It sounds simple, but players often take on six cards at a time, says bingo caller Alan Stockdale from Carlisle.

Some play six games at a time

"I call a number every two seconds or so and if they've got winning line they have to stop the game before I shout the next one.

"Then sometimes one of them will spend a penny and hand her cards over to a friend. So she'll be playing across 12 cards at one time - that's 180 numbers she has to scan, every couple of seconds."

"All our customers are sharp as tacks. They're very, very quick and if I call a number wrong - if I say 23 instead of 22 - they're on my case in a flash."

Other "tricks" include playing the cards upside down and competitors knitting as they play.

Fitness

So do bingo players play for fun or fitness?

Both, says pensioner Edie Childs, who tries never to miss the Monday afternoon session at her local day centre.

The prizes are paltry compared to the big bingo halls, but that doesn't detract from the spirit.

"You'd be surprised how excited people can get for �3. You can hear a pin drop when they're calling the numbers and afterwards, it's like a henhouse," says Edie, 76, of Stockton, Warwickshire.

OAP ages in bingo lingo

60 - Blind 60 65 - Stop Work 66 - Clickety Click 76 - Trombones 77 - Two little crutches 88 - Two fat ladies

The social side is important as well, says Julie Winstone.

"It's a very social game and lots of elderly people say it's the only mental activity they get. That helps ward off depression which has a correlation with mental decline."

And, when, occasionally, Edie finds herself outpaced by the game, she's not adverse to a sneaky tactic.

"You've got to be so quick that sometimes I'll call a line [stop the game] even if I'm not sure I've won. If you're wrong, you can always say you had your thumb over a number."