Our lifespans are limited, but changing thought patterns can slow the ageing process, writes WILLIAM REVILLE
THE FASTEST-growing segment of the world population now is the very old – it is projected that centenarians will number six million worldwide by the year 2050 and 25 per cent of Western populations will be 60 or over. Lifespans increased by about 30 years over the course of the 20th century and much research is under way to discover how to further lengthen lifespan. Some increases can be expected but there is probably a biological limit to attainable human lifespan. However, the good news is that psychological studies have shown your best bet for staying young lies in the old saying, “You’re only as old as you feel.”
Our bodies are made of fundamental biological units called cells. It is possible to take cells from bodily tissues and to grow them in a dish in the laboratory. Supplied with appropriate nutrients, such cells will grow and divide, each into two daughters, each of which will grow and divide again, and so on. It used be thought that, in the absence of some disease developing, such cells would continue to grow and divide forever.
This notion of immortality was demolished in 1961 when microbiologist Leonard Hayflick showed that such cultured cells divide between 40 and 60 times and then die. We can extrapolate from this that there is a biological limit to human life – in other words, even if we never contract a disease we will eventually die when our cells reach their limit and stop dividing. On this basis, human death seems to be inevitable after about 120 years. Incidentally, the world record for human longevity is held by Jeanne Calment, who died in France in 1997, aged 122.
Before a cell divides into two daughters, it duplicates its genetic material (DNA), and then passes identical copies on to each daughter. DNA is a very long double-stranded molecule, capped at both ends by structures called telomeres. The telomeres can be compared to the little metal pieces that cap each end of a shoe lace – if one goes missing the lace frays. Each time the cell divides, the telomeres shorten slightly. Eventually, after many divisions, they disappear and the cell is no longer capable of dividing. This is the biochemical explanation of the Hayflick limit.
Each of our cells has the capacity to make an enzyme called telomerase, which repairs shortened telomeres. The enzyme is suppressed in most cell types, but, if it could be turned on, it would, in theory, greatly prolong cell life. Studies in mice have shown promising results.
A compound found in plants, called resveratrol, has been found to prolong life in animal studies. It acts by regulating the metabolism of cells. It is found in red grapes, peanuts and other foods. A glass of wine contains 1mg of resveratrol. Attempts to develop a resveratrol drug for human use are under way.
But, there is no need to wait on complex technological interventions to improve old age. A simple drug-free intervention is freely available to all. In 1979 Harvard psychologist Ellen Langer carried out a fascinating experiment to see if changing thought patterns can slow aging. Langer assembled a group of men in their 70s and 80s for a “week of reminiscence”, a study of aging designed to see what would happen to the body when the mind went back 20 years in time.
The men were divided into two groups and each group spent a week at a house near Boston. The first group, the control group, simply spent the week reminiscing about the 1950s. But the second group was told to act for the week as if it really was 1950. They were surrounded by props from the 1950s, they watched films and listened to music from the 1950s, discussed 1950s news of the day in the present tense, and so on. The idea was to reconnect their minds to their more vigorous, younger selves.
The environment was set up to prompt the men to behave as healthy, 20 years younger, individuals. There were no wall rails or other gadgets to help them. They weren’t helped with their heavy luggage. They had to prepare their own meals and to make their own choices.
Langer made physiological measurements before and after the week’s retreat. Both groups showed marked improvements, but the experimental group improved the most. Speed of movement, freeness of gait, dexterity, arthritis, cognitive abilities and memory all improved. Eyesight and hearing improved, and blood pressure dropped. Langer concluded that encouraging the mind to think younger actively makes the body younger. Plans are afoot to make a film of Langer’s work, starring Jennifer Aniston.
So, if you are in your advanced years, why not try Langer’s approach – all you have to lose is your cane.
William Reville is a professor in the Biochemistry Dept and public awareness of science officer at UCC. understandingscience.ucc.ie