Ever wonder why some people partake in extremely risky behavior such as skydiving, gambling, driving fast, or other dangerous activities? You may notice that they even seem to be addicted to these activities and go to extreme lengths to find new “fixes”. A study conducted by the journal of neuroscience (http://teachhealthk-12.uthscsa.edu/curriculum/critical-appraisal/Thrill%20Seeking%20Module%20pdfs/Journal%20Article%20Thrill%20Seeking.pdf) has linked the neurotransmitter dopamine to these thrill seeking behaviors in both rats and humans. The study was conducted on 34 subjects and found that persons who reported higher occurrences of thrill seeking behavior have fewer total number of dopamine receptors in their brain. They were also able to conclude that the fewer dopamine receptors is inversely proportional to the amount of the neurotransmitter (dopamine). As we know dopamine is responsible for that good feeling we get when something good or exciting happens. The human brain is able to correlate the memory of the exciting event and the good feeling associated with it. This correlation alone is enough to release dopamine and encourages the individual to recreate the excitement in order to attain the same feeling as before. This may seem very similar to another group of individuals which we know to be drug abusers. Drug use as we know is very addicting and it takes more and more of the drug to feel the same effects as the first time the drug was experienced. This makes people who participate in risky behavior more inclined to drug use. The feeling behind the event is responsible for the addictive properties in both cases.
The results of the experiment can be found graphically in figure 3 in the experiment. It shows direct correlation between the dopamine receptor availability and the subjects thrill seeking score.