Table tennis, ping pong, wiff-waff: call it what you will, it's increasingly popular in the UK, with 2.4 million players. Now there are suggestions it could even help with conditions like dementia.

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First, he took on my dad, writes Channel 4 News Online Producer Jennifer Rigby.

"Let's put money on it," he said. My dad was a little reluctant. While his opponent, Ken Leighton, seemed pretty confident in his own table tennis abilities, dad was a bit less convinced - not least because Ken is 85 years old.

This turned out to be a fairly serious under-estimation of Ken's ping pong skills. Ken thrashed him. Then, a few months later, I played Ken. He thrashed me too.

I reminded him of these games recently.

Let's put money on it. The challenge from 85-year-old table tennis player, Ken Leighton, to his much younger opponent.

"I think your dad thought he wasn't going to get a game... He went home with his tail between his legs," said Ken, laughing. "It's happened before."

Ken started playing table tennis when he was in the army, in 1945. That was 68 years ago.

"I had a decent bat which I still use today," he said. "It's got a mark on the back where my fingers have been - it's taken the rubber off."

Ken plays a singles game in his early twenties (Ken Leighton)

Ping pong for all ages

Ken, who lives in Lancashire, is one of a host of older people who are finding that table tennis is a game for all ages. Last year, a documentary made by Britdoc/Banyak Films called Ping Pong followed eight players on their way to the over-80s world table tennis championships in China.

The 3,500 competitors may be elderly, but they are fierce on the table - and off it.

"This old girl, I don't care how good she is. I should get her. She can't move," says one of the female players, talking about the oldest player in the 2010 tournament: 101-year-old Dorothy DeLow, from Australia.

I was playing table tennis, and I think that saved me. 101-year-old Dorothy DeLow, a competitor in the over-80s table tennis world championships

But the film has a serious side to it as well. Dorothy tells the filmmakers: "I lost my husband and my daughter and I was playing table tennis, and I think that saved me."

Another competitor, Inge Herman, who is 90 in the film, stopped eating and drinking when her husband died 15 years ago, and became "confused". Then she discovered table tennis - and is shown in the film smashing her opponents, clearly together, and seemingly not at all "confused".

Health benefits

Ken would agree that table tennis has helped keep him fit. He recently had to have an operation, which doctors said they would not have undertaken on a man of his age if he wasn't so healthy.

A recent photo of Ken playing table tennis (Ken Leighton)

"Without a shadow of a doubt [it has helped me]. The doctor said if I hadn't been fit, they wouldn't have done the operation. And it's absolutely helped me mentally as well. I think it's great," he said.

Now scientists who have seen the Ping Pong film want to test whether there is any scientific basis behind the improvements some of the characters showed after playing table tennis. At the same time, the filmmakers are taking the film and "ping pong kits" to care homes and community centres around the country to try and encourage older people to play - both for the physical and mental benefits.

Obviously, keeping fit is as good for older people as it is for anyone. But in particular, scientists have shown that exercise is very good at preventing dementia and helping with the symptoms of the disease. But is table tennis any better at this than other sports? Dr Matthew Kempton from the Institute of Psychiatry at King's College London wants to find out.

"You see this film, and you're quite inspired by some of the characters there and some of the changes in their symptoms and the improvement, and what we really want to do now is the science. In the film, it's more anecdotal evidence, what we want to do now is test the science," he told Channel 4 News.

The power of ping pong

He said table tennis has the potential to be helpful for older people with dementia in particular because it combines physical activity with spatial skills, cognition and keeping social.

"Previous research has shown that exercise has actually increased the volume of an area in the brain called the hippocampus," he explained.

"This area is very important in dementia, especially in Alzheimer's disease. It is important in the formation of new memories, and this area gets smaller in people with Alzheimer's. So what we'd be interested in looking at is, while people are playing these table tennis games, or are engaged in more activity, does this area of the brain actually increase in volume? Is there more blood flow and so on, in the hippocampus?"

Because of your age, they think you're a pushover. They said: 'You'll be our secret weapon.' Ken Leighton

The team are trying to get funding now to do the work, but in the meantime experts say that it's part of a wider attempt to encourage older people to keep active, particularly to prevent or help with conditions like Alzheimer's.

George McNamara from the Alzheimer's Society told Channel 4 News: "Every person with dementia is different, and what might be of interest to one person might be table tennis, it might be swimming, it might be talking about the past sporting glories of their football club. But one of the things we do know is that people can live well with dementia."

And Ken? He's not playing right now because of his illness, but he hopes to be back. Just before he got ill, a local team asked him to play for them.

"Because of your age, they think you're a pushover. They said 'you'll be our secret weapon,'" he said.

But while Ken is still hoping to keep his talents under wraps, it's another story for the table tennis campaigners.

If their message gets across in the care homes around the country, they hope potential health benefits of table tennis for older people will not be kept secret for long.