Exercise - gentle walking, a moderate gym session or even dancing and a sing-song - can help people cope with the devastating impact of dementia, researchers believe.
Quite why, the scientists do not yet fully understand.
But unravelling the mysteries of dementia is the key to finding more effective treatments for a condition becoming increasingly common as the population ages.
And while drugs can slow its advance, there are concerns about the over prescription of anti-psychotics for dementia patients.
At the Redholme care home in Liverpool, it is Wednesday morning and the first gym session of the day is about to begin.
A group of four men - all living with dementia, but still relatively fit and able - are very gently put through their paces by Peter Black, one of the staff at the residential home.
The equipment in the room has been modified so it is suitable for people with dementia, most of whom are quite elderly.
So there are no great weights - just some gentle lifting and pushing, with the machines based on a hydraulic system rather like a bicycle pump.
"It's not so much to do with being physical and using muscles, it's all to do with stimulation, says Peter.
"At the end of the exercise people don't go away with aching muscles, they go away laughing, joking, looking at each other - and feeling a lot more confidence in themselves."
Peter says it is all too easy for people with dementia to become withdrawn, but the exercise classes help to bring them out of themselves.
David Dyer is still a physically imposing man.
The tattoos on his forearms are a reminder of his time in the Army and prison service.
Now a resident at Redholme, like many people with dementia he has at times become confused and agitated - even aggressive - with staff.
But the gym sessions seem to help calm him and have become an enjoyable part of his routine, he says, in moderation.
"It's a good method for strengthening different muscles and you can just keep until you reach the stage where you say, well, I've had enough."
And, I ask, it helps keep you in shape?
"It certainly does, yeah. But you wouldn't want to be doing every day, like!"
Redholme has been using the gym equipment for the past two years.
It is only suitable for people in what might be called the middle phase of the condition, before their physical impairment becomes too great.
But over that time the home's owner, Anne McCann, has seen a big difference in the strength and stability of the people in her care, both physically and mentally.
"We've had a reduced number of falls and we find if people are falling that they're not falling and breaking limbs - they'll put their hands out, they'll save themselves, they'll know how to fall - not only for the men but for the ladies as well.
"We've had reduced medication, we've had lots of people taken off anti-psychotic medication from using the equipment and we find the sense of well-being all round is an enhancement."
David Lowery, a research psychologist at the Central and North West London NHS Foundation Trust, is assessing the impact of mild exercise on the behavioural and psychological symptoms of dementia.
"Some of the theories are surrounding the regulation of the sleep-wake cycle, and things around stress, and perhaps blood flow to the brain," he says.
"Stimulation itself could perhaps prevent the brain from degenerating, which is one of the key things with dementia."