Gray matter matters when measuring risk tolerance: May explain why risk tolerance decreases with age

Using a whole-brain analysis, Dr Tymula and international collaborators found that the grey matter volume of a region in the right posterior parietal cortex was significantly predictive of individual risk attitudes. Men and women with higher grey matter volume in this region exhibited less risk aversion.

"Individual risk attitudes are correlated with the grey matter volume in the posterior parietal cortex suggesting existence of an anatomical biomarker for financial risk-attitude," said Dr Tymula.

This means tolerance of risk "could potentially be measured in billions of existing medical brain scans."

But she has cautioned against making a causal link between brain structure and behaviour. More research will be needed to establish whether structural changes in the brain lead to changes in risk attitude or whether that individual's risky choices alter his or her brain structure -- or both.

"The findings fit nicely with our previous findings on risk attitude and ageing. In our Proceedings of the National Academy of Sciences 2013 paper we found that as people age they become more risk averse," she said.

"From other work we know that cortex thins substantially as we age. It is possible that changes in risk attitude over lifespan are caused by thinning of the cortex."

Study participants included young adult men and women from the northeastern United States. Participants made a series of choices between monetary lotteries that varied in their degree of risk, and the research team conducted standard anatomical MRI brain scans. The results were first obtained in a group of 28 participants, and then confirmed in a second, independent, group of 33 participants.

The study was a collaboration of researchers from the University of Sydney, Yale, University College London, New York University, and the University of Pennsylvania. In addition to Tymula, authors include Sharon Gilaie-Dotan, Ifat Levy, Nicole Cooper, Joseph W. Kable, and Paul W. Glimcher.

The findings are published in the September 10 issue of The Journal of Neuroscience.