In 1979 psychologist Ellen Langer carried out an experiment to find if changing thought patterns could slow ageing. But the full story of the extraordinary experiment has been hidden until now.
How much control do you have over how you will age?
Many people would laugh at the idea that people could influence the state of their health in old age by positive thinking. A way of mitigating ageing is a holy grail for the pharmaceutical and cosmetics industry, but an experiment by Harvard psychologist Ellen Langer three decades ago could hold significant clues.
Prof Langer has spent her entire career investigating the power our mind has over our health. Conventional medicine is frequently accused of treating them as separate entities.
"Everybody knows in some way that our minds affect our physical being, but I don't think people are aware of just how profound the effect actually is," she says.
In 1979, Prof Langer conducted a ground-breaking experiment - the results of which are only now being fully revealed.
Prof Langer recruited a group of elderly men all in their late 70s or 80s for what she described as a "week of reminiscence". They were not told they were taking part in a study into ageing, an experiment that would transport them 20 years back in time.
The psychologist wanted to know if she could put the mind back 20 years would the body show any changes.
The men were split into two groups. They would both be spending a week at a retreat outside of Boston.
Ellen Langer in 1979 and today
But while the first group, the control, really would be reminiscing about life in the 50s, the other half would be in a timewarp. Surrounded by props from the 50s the experimental group would be asked to act as if it was actually 1959.
They watched films, listened to music from the time and had discussions about Castro marching on Havana and the latest Nasa satellite launch - all in the present tense.
Dr Langer believed she could reconnect their minds with their younger and more vigorous selves by placing them in an environment connected with their own past lives.
And she was determined to remove any prompt for them to behave as anything but healthy individuals. The retreat was not equipped with rails or any gadgets that would help older people. Right from the off she was determined to ensure they looked after themselves.
When they got off the bus at the retreat, Prof Langer did not help the men carry their suitcases in. "I told them they could move them an inch at a time, they could unpack them right at the bus and take up a shirt at a time."
The men were entirely immersed in an era when they were 20 years younger.
Understandably, Prof Langer herself had doubts. "You have to understand, when these people came to see if they could be in the study and they were walking down the hall to get to my office, they looked like they were on their last legs, so much so that I said to my students 'why are we doing this? It's too risky'."
But soon the men were making their own meals. They were making their own choices. They weren't being treated as incompetent or sick.
Pretty soon she could see a difference. Over the days, Prof Langer began to notice that they were walking faster and their confidence had improved. By the final morning one man had even decided he could do without his walking stick.
As they waited for the bus to return them to Boston, Prof Langer asked one of the men if he would like to play a game of catch, within a few minutes it had turned into an impromptu game of "touch" American football.
Obviously this kind of anecdotal evidence does not count for much in a study.
But Prof Langer took physiological measurements both before and after the week and found the men improved across the board. Their gait, dexterity, arthritis, speed of movement, cognitive abilities and their memory was all measurably improved.
Their blood pressure dropped and, even more surprisingly, their eyesight and hearing got better. Both groups showed improvements, but the experimental group improved the most.
Prof Langer believes that by encouraging the men's minds to think younger their bodies followed and actually became "younger".
She first published the scientific data in 1981 but she left out many of the more colourful stories. As a young academic, she feared this might taint the experiment and affect the acceptance of the results.
Now after over 30 years of research into the connection between the mind and the body and with the confidence and conviction of a Harvard professor, she feels she has a fuller story to tell.
"My own view of ageing is that one can, not the rare person but the average person, live a very full life, without infirmity, without loss of memory that is debilitating, without many of the things we fear."
Richard Wiseman, professor of public understanding of psychology at the University of Hertfordshire, thinks the results of Prof Langer's experiments are fascinating but the big question is what's causing them. "I think there could be multiple things going on here and the question is which explanations really hold water.
"Part of it could be self perception, for example if you get people to smile they feel happier. The same could be going on here, by getting people to act younger they feel younger."
Prof Weisman believes another factor could be motivational, the men are simply trying harder by the end of the week, or it could be similar to hypnotism, where people do better on memory tests because they are told they have a better memory.
Whatever the cause he believes there is a place for the type of positive thinking shown in the study.
"If you take something like heart disease positive thinking can have a role, because while it won't heal your heart on its own, positive thinking will feed into positive actions like healthy eating or exercise which will help."
In any event there is likely to be more interest in the 1979 experiment. The retelling of the study has been snapped up by Jennifer Aniston's new production company, with Aniston tipped to play Prof Langer.