In a new study, scientists have found that risk takers pursue a life of danger and thrills in a bid to stimulate their minds which are less responsive to excitement than normal.
Researchers at the Vanderbilt Kennedy Center for Research on Human Development found that impulsive characters are less able to react to dopamine, a substance produced naturally in the brain that triggers feelings of wellbeing and reward.
They believe that this means that these individuals must take bigger risks in order to achieve the same feelings of excitement that others get regularly.
The study revealed that novelty seekers have less of a particular type of dopamine receptor, which may lead them to seek out novel and exciting experiences. This can manifest itself in activities such as reckless spending, taking risks and taking drugs.
"We've found that the density of these dopamine autoreceptors is inversely related to an individual's interest in and desire for novel experiences," David Zald, associate professor of psychology and lead author of the study at the Vanderbilt Kennedy Center for Research on Human Development.
Dopamine has long been known to play an important role in how we experience rewards from a variety of natural sources, including food and sex, as well as from drugs such as cocaine and amphetamine.
Previous studies have shown that individuals differ in both their number of dopamine receptors and the amount of dopamine they produce, and that these differences may play a significant role in addiction.
Zald and his colleagues set out to explore the connection between dopamine receptors and the novelty-seeking personality trait.
The researchers used brain-scanning techniques to view the levels of dopamine receptors in 34 healthy humans who had taken a questionnaire that measured the novelty-seeking personality trait.
The questionnaire measured things such as an individual's preference for and response to novelty, decision-making speed, a person's readiness to freely spend money, and the extent to which a person is spontaneous and unconstrained by rules and regulations.
The higher the score, the more likely the person was to be a novelty seeker.
The researchers found that those that scored higher on the novelty-seeking scale had decreased dopamine autoreceptor availability compared to the subjects that scored lower.
The study appears in the Journal of Neuroscience.