MedicalResearch.com Interview with:
Ifat Levy, PhD
Comparative Med and Neuroscience
Yale School of Medicine
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The proportion of older adults in the population is rapidly rising. These older adults need to make many important decisions, including medical and financial ones, and therefore understanding age-related changes in decision making is of high importance. Prior research has shown that older adults tend to be more risk averse than their younger counterparts when making choices between sure gains and lotteries. For example, asked to choose between receiving $5 for sure and playing a lottery with 50% of gaining $12 (but also 50% of gaining nothing), older adults are more likely than young adults to prefer the safe $5. We were interested in understanding the neurobiological mechanisms that are involved in these age-related shifts in preferences.
An earlier study that we have conducted in young adults provided a clue. In that study, we measured the risk preference of each participant (based on a series of choices they made between safe and risky options), and also used MRI to obtain a 3D image of their brain. Comparing the behavioral and anatomical measures, we found an association between individual risk preferences and the gray-matter volume of a particular brain area, known as “right posterior parietal cortex” (rPPC), which is located at the back of the right side of the brain. Participants with more gray matter in that brain area were, on average, more tolerant of risk (or less risk averse).
This suggested a very interesting possibility – that perhaps the increase in risk aversion observed in older adults is linked to the thinning of gray matter which is also observed in elders. In the current study we set out to test this hypothesis, by measuring risk preference and gray matter density in a group of 52 participants between the ages of 18 and 88. We found that, as expected, older participants were more risk averse than younger ones, and also had less gray matter in their rPPC. We also replicated our previous finding – that less gray matter was associated with higher risk aversion. The critical finding, however, was that the gray matter volume was a better predictor of increased risk aversion than age itself. Essentially, if both age and the gray matter volume of rPPC were used in the same statistical model, rPPC volume predicted risk preferences, while age did not. Moreover, the predictive power was specific to the rPPC – when we added the total gray matter volume to the model, it did not show such predictive power.
MedicalResearch.com: What should readers take away from your report?
Response: Our study makes an initial step towards understanding the neural mechanisms of changes in risky decision making with aging. Such understanding is important because it will ultimately help us to predict age-related changes in decision making and will aid in ensuring that older adults make the decisions that are best for them. The rPPC is an interesting brain area, which has been implicated in many processes that transform sensation into action, including decision making processes. We now have a link between the amount of gray matter volume in this area and individual risk preferences, and this link explains age-related changes in risk preference better than age.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: The next intriguing question is what the anatomical change that we observed means at the neural level – does less volume mean less neurons? Less synaptic connections? Smaller neurons? Also, what comes first – does brain structure give rise to behavior or the other way around? Or, perhaps both brain and behavior are shaped by life experience? The answer is probably a combination of all of these, but longitudinal studies are required to answer it.
MedicalResearch.com: Is there anything else you would like to add?
Response: The study is a collaboration between several academic institutions, primarily Yale University and New York University, and includes investigators with expertise in various neuroscientific fields as well as in economics. It is an example for how interdisciplinary research is important for promoting scientific discoveries. The research was funded by grants from the National Institute on Aging (NIA), part of the National Institutes of Health (NIH).
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Nature Communications 7, Article number: 13822 (2016)
Michael A. Grubb, Agnieszka Tymula Sharon Gilaie-Dotan, Paul W. Glimcher
& Ifat Levy
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