There’s no reason to give up a favourite sport if you’re diagnosed with Alzheimer’s or dementia.

When Malcolm Watt steps onto a tennis court he remains one of the best players in the country for his age. But when he’s finished thrashing his opponent a very different man emerges; one who cannot hold a conversation or care for himself anymore. For Malcom, who is only 46, has frontotemporal dementia.

As a teenager, the Scottish born player was ranked fourth in Britain and destined for great things. Whilst dementia has robbed him of his ability to communicate even his most basic needs, it has not affected his ability to play the sport he clearly loves.

‘Tennis has been a saving grace,’ his father Tommy said recently. ‘The doctor who diagnosed him explained that whilst they don’t fully understand the illness, some elements of behaviour like competitive instinct are hard wired into the brain.

‘Malcolm has been playing tennis since he was 11. His brain is still instructing his body to work in the same way.’

Remaining fit and active may, say experts, help to slow down the progress of dementia, and it can certainly enhance quality of life. ‘Now tennis is the only interest in Malcolm’s life,’ adds Tommy. ‘I couldn’t emphasis enough the importance of the game in his life. On the tennis court you wouldn’t think anything was wrong with him.’

Not all sport is the same however. In fact, frequent blows to the head from sports such as boxing and rugby may actually cause chronic brain disorders such as dementia and Parkinson’s. Champion boxer Sugar Ray Robinson – frequently cited as the greatest boxer of all time - died at the age of 67 with Alzheimer’s disease. Whether boxing legend Mohammad Ali’s diagnosis with Parkinson’s in 1984 came as a result of his career (and the estimated 29,000 blows he suffered to his head) is still a subject of debate.

But whilst professional boxing may well damage the brain, many people find that a sport which has kept them physically fit and healthy, can also make a dementia diagnosis a little easier to live with – in the early stages at least.

Football legend Jimmy Hill, the face of Match of the Day for 25 years, was a sprightly octogenarian when he was diagnosed with Alzheimer’s and lived a further seven years before his death in December, deriving particular pleasure, according to his wife Bryony, from animals and music.

And while Malcom Watt’s diagnosis at 42 came tragically early, at least he and his family can derive pleasure from knowing that the sport he loves continues to work its magic, and bring Malcom enjoyment.

If playing sport is out of the question, cherished sporting memories can also be used to help tackle dementia. The Sporting Memories Network uses sport reminiscence to engage people with dementia and increase their confidence. The charity runs groups and workshops nationwide which spark widespread enthusiasm and ease loneliness and depression.