Newswise — Age itself is not the determining factor in how an individual views or tolerates risk when making decisions; instead, it is the age-related decline in the volume of gray matter in our brains, research by NYU’s Institute for the Interdisciplinary Study of Decision Making shows.

“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 co-author Paul Glimcher, a professor at NYU’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.”

“Older adults need to make many important financial and medical decisions, often under high levels of uncertainty,” adds lead author Ifat Levy, an associate professor of comparative medicine and of neuroscience at Yale University and visiting professor at IISDM. “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. The researchers also measured the gray matter volume in the posterior parietal cortex of each subject, drawn from MRI scans. After analyzing the risk choices and MRI measurements, the researchers confirmed that age-related decline in risk tolerance correlates more with changes in brain anatomy than with age.

The study’s other authors were: Michael Grubb, an NYU postdoctoral fellow at the time of the study and now an assistant professor at Trinity College in Connecticut; Agnieszka Tymula, a senior lecturer at the University of Sydney; and Sharon Gilaie-Dotan, a postdoctoral fellow at University College London.

The research was supported by grants from the National Institutes of Health (R01 5R01AG033406, R21AG049293); the DOI for this paper will be 10.1038/NCOMMS13822.

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Nature Communications