Thrill seeking as associated with low activity in the frontal cortex of the brain.
The frontal cortex is used in rational decision making and inhibiting arousal from addictive behaviors.
In thrill seeking individuals, high risk activities activate the same part of the brain that craves nicotine, drugs or sex or other addictive behaviors while the frontal cortex shows normal or low activity.
In normal people, high risk activities activate the frontal cortex which makes people afraid and careful.
the condition may be genetic and would help explain why Russian kids are engaging in risky activities in greater numbers.
Possible causes
Several theories exist to try to explain the prevalence of risky behaviors in Russian kids.
Soviet government cultivating people with tendencies to ignore risks in order to create fearless soldiers. (very debated)
Alcohol foetal syndrome where expecting mothers consume large quantities of alcohol may create children with abnormal brains.
Unbalances with dopamine and testosterone play a role in thrill seeking behaviors and the causes may also be genetic.