The study found that 15- and 16-year-olds who enjoy activities, such as giving their money to family members, are less likely to become depressed than those who get a bigger thrill from taking risks or keeping the money for themselves.
Researchers from the University of Illinois and the University of California, Los Angeles focused on the ventral striatum, a brain region that regulates feelings of pleasure in response to rewards.
Previous research has shown that ventral striatum activity tends to be more pronounced in adolescence, suggesting that people at this age experience the pleasure of rewards more intensely than younger children or adults.
"There's this trend where from childhood to adolescence, morbidity and mortality rates increase 200 to 300 per cent, and it's almost entirely due to these preventable risk-taking behaviours," she said.
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Depressive symptoms also tend to increase during this time, she said.
Using a functional brain scan, the researchers measured ventral striatum activity in adolescents who engaged in tasks that involved either giving money to others, keeping the money or making risky financial decisions in the hope of earning a reward.
The researchers found that activity in the ventral striatum in response to different rewards predicted whether the subjects' depressive symptoms would worsen - or lessen - over time.
"If they show higher levels of reward activation in the ventral striatum in the context of the risk-taking task, they show increases in depressive symptoms over time," said Telzer, who also is a professor in the Beckman Institute for Advanced Science and Technology.
"And if they show higher reward activation in the pro-social context, they show declines in depression," she said.