Although the term "adrenaline junkie" is normally used facetiously and without any genuine implication of addiction, there may be an element of truth to the description. Psychological addiction to an "adrenaline rush" has been reported numerous times.
An adrenaline rush is usually accompanied by an increase in endorphin activity. Endorphins are responsible for feelings of well being, as well as pain relief. Due to synaptic plasticity, increased endorphin activity creates an increase in endorphin receptor sites, which in turn can create a stronger desire for endorphins. Synaptic plasticity and receptor site proliferation are widely believed to be the mechanisms by which chemical addictions are developed.
However, the same can be said for any endorphin-stimulating activity, whether laughter, physical exertion, sex, artistic expression or religious experience. Although synaptic plasticity may be responsible for chemical addictions, it is also believed to be involved in reinforcement, the mechanism by which animals learn to differentiate what is desirable from what is undesirable. Seen in this context, chemical addiction could simply be seen as an aberrant form of plasticity.
Although the effects of adrenaline are largely positive, increasing cardiovascular activity and oxygenation, extended or chronic adrenal stimulation can eventually lead to high blood pressure, heart disease, and other stress-related diseases.