Some people are fond of doing risky behaviors, like driving above the speed limit or leaving a steady paycheck to start a business. Others can bravely take risks, while some people navigate through life by following rules or the norm. So how are these two types of people differ from each other?
Assistant Professor of marketing Gideon Nave of The Wharton School of the University of Pennsylvania said that people have different tendencies to engage in behavior that may risk their health or future.
But explaining how these tendencies originated in the genome and the brain has proven to be challenging, partly because of the small sample that previous studies have used.
That has seemed to change recently, with researchers from the University of Zurich's Gökhan Aydogan led by Nave revealing the genetic disposition of risky behavior embodied in the brain. They studied the brain scans and genetic data of over 12,000 people to understand the association between brain anatomy and risky behavior.
They published their findings in the journal Nature Human Behavior.
No One Risk Region in the Brain
According to Nave, they found no single risk region in the brain that is solely responsible for the behavior. They found that there are several brain regions whose anatomy is altered in people who take risks, Penn Today reported.
The new study looked at four self-reported behaviors among the biomedical data from 500,000 volunteer participants from the UK biobank's robust dataset. These four behaviors are smoking, drinking, sexual promiscuity, and driving above the speed limit.
Moreover, the researchers used the data from 12,675 people of European ancestry from the UK Biobank to drill down the connections between genes, brain, and risk tolerance. They estimated the relationship between the total gray matter across the brain and the risk-tolerance score.
The researchers found that the higher risk tolerance for risky behavior was correlated with the overall gray matter volume. Gray matter is a major part of the nervous system that contains neuronal cell bodies, neuropil, glial cells, synapses, and capillaries. It is responsible for muscle control, sensory perception, and decision making.
Moreover, they also looked at which specific regions of the brain have the strongest correlation with risky behaviors and reduced gray matter. They found associations in distinct brain regions, such as the amygdala, hippocampus, and areas in the cerebellum.
The amygdala regulates the feelings of fear and is considered the seat of emotion, which is also activated when making risky decisions based on the fMRI studies. While the hippocampus is involved in creating new memories, and the cerebellum is responsible for balance and coordination.
"We find that we don't have only one brain region that is the 'risk area,'" Nave says. "There are a lot of regions involved, and the effect sizes we found are not that large but also not that small."
The Genetic Disposition for Risky Behaviors
The research team also studied the genetic disposition for the risk behavior to distinguish how genes, the brain, and behavior correlates with risk-taking.
According to Medical Xpress, they developed the polygenic risk score that measures genetic variation and found that it can explain 3% of the risky behavior.
Also, they looked at the three brain regions and determined that differences in the gray matter in these regions carried out around 2.2% of genetic disposition toward risky behavior.
"It appears that grey matter of these three regions is translating a genetic tendency into actual behavior," said co-author Philipp Koellinger from Vrej University Amsterdam.
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