Declining levels of dopamine mean older people are less likely to choose risky gambles than younger people because they are no longer attracted by potential rewards, according to a new study.
A study by researchers at University College, London, UK, published in Current Biology, found that older people were reluctant to take "unnecessary risks."
Researchers found that, like younger people, they would take risks to avoid losses in a game.
But they would not take big risks for the sake of gain.
Dr Robb Rutledge from the UCL Institute of Neurology and Max Planck UCL Centre for Computational Psychiatry and Ageing Research, said the effects they saw in the experiment may be due to dopamine decline because age is 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,” he said. “Older people were simply less attracted to big rewards and this made them less willing to take risks to try to get them.”
The experiment saw 25,189 smartphone users aged 18-69 play The Great Brain Experiment, in which players start with 500 points and aim to win maximum points in 30 different trials, choosing a safe option or a 50/50 gamble.
In the ‘gain’ trials, players could choose a guaranteed number of points or a 50/50 chance of winning more points or gaining nothing. The ‘loss’ trials enabled players to lose a fixed number of points or gamble with a chance of losing more points or nothing. In the ‘mixed’ trials, players chose zero points or could gamble with a chance of either gaining or losing points.
On average, all age groups gambled in about 56% of the loss trials and 67% of the mixed trials. In the gain trials, however, 18-24 year olds gambled 72% of the time and this rate fell steadily to 64% in the 60-69 age group.
The study also involved mathematical equations that enabled the research team to make specific predictions about how dopamine loss would affect decision making.
“A loss of dopamine may explain why older people are less attracted to the promise of potential rewards,” said Dr Rutledge. “Decisions involving potential losses were unaffected and this may be because different processes important for losses are not affected by ageing.
“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.
“They already know that negative messaging helps to persuade older people, whereas a more optimistic approach that emphasises 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.”
Dr Raliza Stoyanova, from the Neuroscience and Mental Health team at Wellcome, which funded the study, said the study demonstrated that digital technology could produce new and robust insights into the workings of the brain.
“Smartphone apps allowed the researchers to capture decision-making outside of typical ‘lab’ settings, and to reach more people from varied backgrounds than is typically possible,” she said.
“It will be exciting to see what else the data generated from the Great Brain Experiment will reveal about risk and decision-making, as well as other complex brain processes like memory and attention.”
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