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Older adults are less inclined to take risks, but this behavior may be linked to changes in brain anatomy rather than age, new research shows.

“Older adults need to make many important financial and medical decisions, often under high levels of uncertainty,” says lead author Ifat Levy, an associate professor of comparative medicine and of neuroscience at Yale University.

“We know that decision-making changes with age, but we don’t really know what the biological basis of these changes is. In this paper, we make the first step towards answering this question, by showing that the decrease in gray matter volume in a particular part of the brain—posterior parietal cortex—accounts for the increase in risk aversion observed with age.”

The study, which appears in the journal Nature Communications, focused on the right posterior parietal cortex (rPPC)—a part of the brain involved in planning movements, spatial reasoning, and attention.

For the study, the research team presented a series of choices to 52 study participants, aged 18 to 88 years Participants could either receive $5 or take their chances with a lottery of varying amounts and probabilities. For example, a participant could choose the certain gain of $5 or opt for a 25 percent chance of getting $20. Participants were each assigned a number denoting their level of risk tolerance based on their choices.

The researchers also measured the gray matter volume in the posterior parietal cortex of each subject, drawn from MRI scans.

“We found that if we use both the gray matter volume and age together as predictors of risk attitudes, the gray matter volume is significant, while age is not,” says Levy. “This means that gray matter volume accounts for age-related changes in risk attitude more than age itself.”

The finding provides new insight into neurological factors that affect risk preferences and decision-making among older adults. It may also lead to strategies for modifying decision-making.

“These results provide a basis for understanding the neural mechanisms involved in risky choices and offer a glimpse into the dynamics that affect decision-making in an aging population,” explains study coauthor Paul Glimcher, a professor at New York University’s Center for Neural Science and director of the Interdisciplinary Study of Decision Making (IISDM).

“This research can help us improve how we communicate with the elderly about complex issues that may present risks to them.”

Grants from the National Institute on Aging (National Institutes of Health) supported the work.

Source: Yale University, James Devitt for New York University