People who engage in risky behaviors have a reduced volume of gray matter. This is related to muscle control and decision making.
- The researchers did not identify a particular risk-taking area in the brain, but several associations between this behavior and brain anatomy.
- The areas of the brain with the least gray matter correlated with risky behaviors are the amygdala, hippocampus, and cerebellum.
- A genetic study has revealed that genes can explain only 3% of the variation in risky behavior.
Researchers have discovered the brain signature of hotheads. People who take the most risks, putting their lives in danger, or who adopt behaviors that lead to uncertainties for the future, have a somewhat reduced volume of gray matter. A discovery made by a team of American researchers from the Wharton School in Pennsylvania and published on January 28 in the journal Nature Human Behavior. The researchers point out that gray matter comprises most of the major cell bodies of neurons in the central nervous system and is believed to perform basic functions of the brain, including muscle control, sensory perception and decision-making.
Not a particular area in the brain
To discover this link between risk-taking and gray matter, the researchers conducted a massive study using brain scintigraphy, a functional imaging technique that makes it possible to visualize the functioning of organs. They also studied the genetic data of 12,675 adults participating in the UK Biobank, a large study that has observed the respective contributions of genetic predisposition and environmental exposure to the development of the disease since 2006. The researchers aim to to be able to explain the origin of risky behaviors both in the genome and in the brain, and to identify the neuroanatomical correlates of risk taking.
The researchers did not identify a particular risk-taking area in the brain, but several associations between this behavior and brain anatomy. “There is not a single region of risk in the braincontinues Gideo Nave, author of the study. We identify many regions with altered anatomy in people who take risks.” To make the connection, the researchers focused on 4 self-reported risky behaviors: smoking, drinking, sexual promiscuity and driving above the speed limit. They then created a risk tolerance index before measuring the total volume of gray matter in the participants’ brains.
Risk-taking genes
The results revealed a correlation between higher risk tolerance and lower overall gray matter volume. A result that was confirmed after taking into account various possible confounding factors including the total size of the brain, age, sex, sensitivity, excessive alcohol consumption and genetic factors. Looking more specifically at brain areas has shown associations with several distinct brain regions including the amygdala, which is involved in fear and emotion. Researchers have identified lower levels of gray matter in other parts of the brain that are associated with the propensity to take more risks. These are the hippocampus, linked to the creation of new memories, and the cerebellum, involved in balance and coordination. “There are many regions involved, with non-negligible effect sizes”, wrote the researchers.
The researchers also looked for risk-taking genes. Thanks to a measurement of genetic variation involving nearly 300,000 people, they discovered that this risk score only explains 3% of the variation in risky behavior. However, this score appears to be correlated with the reduction in gray matter volume in 3 specific brain areas. “It appears that the gray matter volumes of these 3 regions represent a genetic tendency to actual risk-taking behavior”, they conclude.
Researchers suggest that family, environmental or even genetic factors, as well as a correlation between all these factors, could promote risky behavior. These first data, which only explain a few percent of the genetic disposition, call for further research.
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