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Older folks tend not to engage as much in risky behavior as teenagers and young adults do. You might call that wisdom or learned experience. But this also may be a result of older brains having less gray matter in a certain spot, according to a new study.

Researchers found that adults who were less inclined to take risks had less gray matter in the right posterior parietal cortex, which is involved in decisions that entail risk.

In the study, the researchers asked volunteers ranging in age from 18 to 88 to play a game involving risk. The participants were allowed to choose between a guaranteed gain, such as pocketing $5, or an uncertain gain, such as a lottery to earn between $5 and $120 with varying chances of winning or losing.

As the researchers expected, those participants who chose the guaranteed gain — that is, no risk — tended to be older than those who opted for the lottery. It wasn’t a perfect correlation, but it was close. One could call this old-age wisdom. [7 Ways the Mind and Body Change With Age]

Yet when the researchers analyzed brain scans of these volunteers obtained through an MRI technique called voxel-based morphometry (VBM), they found that lower levels of gray matter, even more than age, best accounted for risk aversion.

These results suggest that the brain changes that occur in healthy aging people may be behind more decision-making patterns and preferences than previously thought, the researchers noted in their findings, published Dec. 13 in the journal Nature Communications.

The relationship among decreased risk-taking, declining gray matter and aging makes sense from an evolutionary viewpoint, said Ifat Levy, an associate professor of comparative medicine and of neuroscience at Yale University, senior author on the study.

“In many ways, it makes sense for older adults to take less risks than younger ones, both because they may be less able to stand the consequences and because they have less time to live and ‘fix’ the damage,” Levy said. “Another way to think about it is that, for older adults, it may be enough to have just a little bit — of food, money, etc. — to keep them going, so they don’t need to take the chance. Younger adults need to take care of offspring and so on, and the ‘safe’ option may simply not be enough to achieve everything they need.”

Levy said that she would like to extend the brain research to adolescents. In a previous study, Levy and her colleagues demonstrated that teenagers have a tolerance for ambiguity, which can increase their participation in risky behavior when the risk is unknown.

Michael Grubb, first author on the new study — who at the time of conducting it was at New York University and is now an assistant professor at Trinity College in Hartford, Conn. — said the research team had only just begun to scan the brains of adolescents, and it was not yet clear how levels of gray matter affect their affinity for risk.

“The picture is complex,” Levy said, with factors such as peer pressure and a brain not yet fully developed acting as contributing factors.

Or, for teenagers, it may be that the answer is gray.

— Live Science

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