Older people take fewer risks because of declining levels of a brain chemical linked to reward and impulsive behaviours, a new study found.
The young are often seen as willing to take more risks but older people are seen as more conservative and less likely to gamble for a big reward..
Now scientists from University College London suggest a drop in the neurotransmitting chemical dopamine makes older people more risk-averse for gain.
The study of over 25,000 people aged 18 to 69 found older people were less likely to choose risky gambles to win more points in a smartphone app called The Great Brain Experiment.
But they were no different to younger participants when it came to choosing risky gambles to avoid losing points.
While it is widely believed older people don't take risks, the study showed exactly what kind of risks older people avoid.
It found the steady decline in risky choices with age matches a steady decline in dopamine levels with them falling by up to 10 per cent every decade in adulthood.
Previously the researchers found volunteers chose significantly more risky gambles to win more money when given a drug that boosted dopamine levels.
Lead author senior research associate Dr Robb Rutledge said: "As we age, our dopamine levels naturally decline, which could explain why we are less likely to seek rewards.
"The effects we saw in the experiment may be due to dopamine decline, since age was associated with only one type of risk taking and mirrored the known effects of dopamine drugs on decision making.
"Older people were not more risk-averse overall, and they didn't make more mistakes than young people did.
"Older people were simply less attracted to big rewards and this made them less willing to take risks to try to get them."
In the experiment the game app involves gambling for points with each player starting with 500 points.
The aim is to win as many points as possible in thirty different trials where they must choose between a safe option and a risky 50/50 gamble.
In the 'gain' trials, players can either choose a guaranteed number of points or a 50/50 chance of winning more points or gaining nothing.
The 'loss' trials are the same in reverse, where players can lose a fixed number of points or gamble with a chance of losing more points or nothing.
In the 'mixed' trials, players can choose zero points or to gamble with a chance of either gaining or losing points.
On average, all age groups chose to gamble in approximately 56 per cent of the loss trials and 67 per cent of the mixed trials.
In the gain trials, 18 to 24 year olds gambled in 72 per cent of trials and this fell steadily to 64 per cent in the 60 to 69 age group.
Dr Rutledge added: "A loss of dopamine may explain why older people are less attracted to the promise of potential rewards.
"Decisions involving potential losses were unaffected and this may be because different processes important for losses are not affected by ageing.”
He also suggested the findings could have implications for political arguments.
"Political campaigners often frame voting decisions negatively, for example saying that UK households would be £4,300 worse off if the UK decides later this month to leave the EU rather than £4,300 better off if the UK decides to remain part of the EU,” he noted.
"They already know that negative messaging helps to persuade older people, whereas a more optimistic approach that emphasizes large potential rewards might appeal more to younger people who are less likely to vote.
"Our new findings offer a potential neuroscientific explanation, suggesting that a natural decline in dopamine with age might make people less receptive to the positive approach than they would have been when they were younger."
The study was published in Current Biology.