Around 850,000 people in Britain are currently living with dementia a figure that is expected to hit one million by 2025.
Yet although billions of pounds has been spent trying to a drug to halt or reverse dementia, there is still no therapy, and several pharmaceutical companies have now pulled out of research because of ongoing setbacks.
The search for the literal ‘holy grail’ of youth dates back throughout humanity but scientists are divided on what causes ageing and what can be done about it.
Theories of why humans grow old include the ‘free radical theory’ which suggests that as mitochondria – the cell batteries – burn up oxygen as a fuel they also produce unstable compounds which rampage through the body damaging important molecules and proteins.
However despite many claims that anti-oxidants could prevent ageing, no studies have shown they actually make a difference.
Ageing may also be caused by senescence, when a cell goes dormant, unable to replicate but still alive so it is not cleared out by the body’s waste system. Growing older may also be price of tumour suppression, killing off cells before they have the chance to become cancerous, some scientists believe.
The only proven way to prevent ageing is to restrict calories to around two thirds of usual intake, which has been shown in animals to extend lifespan by around 50 per cent. For humans that would mean potentially living to 180.
“There are people who follow this regime, but it’s very difficult. Our brain is wired to search for food and eat as much as it can,” added Prof Giacca.
“Nobody even knows why some animals live longer than others. There is a theory that bigger animals live longer, but it doesn’t always hold true, and we don’t know why it would be.
“But what we do know is that we lost 80,000 neurons every day, and we haven’t yet found a way to regenerate them, so a person who reaches 80 or 90 has already lost about 10 to 15 per cent of their brain, which is why they think and move more slowly.
“And that’s before diseases like Alzheimer’s where you have accelerated neuron loss, so if you don’t deal with those problems you could end up with a healthy heart but a head that is stupid.”