What’s the use of living longer if we all turn into zombies?
Lack of progress in ways to regenerate brain cells may create an ageing generation with feeble brains, an expert warns
Increasing human lifespan risks creating huge numbers of zombie-like humans because experts are not close to curing dementia and brain cell loss, a leading scientist has warned.
Labs across the world are trying to tackle the causes of ageing and have made important breakthroughs in understanding why cells grow old and die, and how to stop the process. Likewise, improvements in treating diseases such as cancer, and advances in vaccination and nutrition mean populations are living longer. The oldest person on record, Jeanne Calment, died in 1997 at the age of 122, and scientists now think that 120 is about the maximum age humans can reach, although a hugely restrictive diet could push the window to 180.
But Mauro Giacca, a professor in cardiovascular sciences at King’s College London, said keeping the body alive for longer was a pointless endeavour unless we learnt to tackle neurodegeneration and worked out how to regenerate brain cells.
“Why do we age? The short answer is we just don’t know,” he told a symposium at the Francis Crick Institute in London. “There are more than 30 theories about why humans age. It is likely there is a biological clock which sets human life around 120 and we are programmed not to live longer than that,” he said.
“But the probability of undergoing dementia is increasing with the passing of age and the risk we are facing as we trigger regeneration and recover limbs is if we don’t find a way to regenerate the brain we will increase the number of perfectly functioning bodies but with poorly functioning brains.”
About 850,000 people in Britain have dementia, a figure expected to hit one million by 2025. Yet, although billions of pounds have been spent on trying to develop a drug to halt or reverse dementia, there is still no therapy.
Theories about why humans grow old include the “free radical”, which suggests that as mitochondria (the cell batteries) burn up oxygen they produce unstable compounds that damage molecules and proteins. But despite many claims that antioxidants could prevent ageing, no studies have shown they make a difference.
Ageing may also be caused by senescence, when a cell goes dormant, unable to replicate, but is not cleared out by the body’s waste system. Growing older may also be the price of tumour suppression, the killing off of cells before they become cancerous.
The only proven way to prevent ageing is to restrict calories to about two-thirds of the usual intake, which has been shown in animals to extend life span by about 50%. For humans that would mean potentially living to the age of 180.
“There are people who follow this regime, but it’s very difficult. Our brain is wired to search for food,” said Giacca. “We [lose] 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% of their brain, which is why they think and move more slowly.
“That’s before diseases like Alzheimer’s ... so if you don’t deal with those problems you could end up with a healthy heart but a head that is stupid.”
– © The Daily Telegraph