Java, Joe, Espresso, Coffee, Starbucks…
Whichever you call it, they all contain caffeine, a central nervous system stimulant, that National Geographic Magazine calls the world’s most popular psychoactive drug.
Mechanism of Action:
Caffeine resembles a naturally occurring substance in the brain called adenosine.
Caffeine does have a high attraction (affinity) for adenosine receptors in the nervous system, but caffeine’s effect on the body is not like that of adenosines. Caffeine blocks access of adenosine to its receptors and thus caffeine is classified as an adenosine antagonist. The role of adenosine is associated with sedation of parts of the central nervous system. By blocking the effects of adenosine which puts on the cellular brakes, caffeine is able to provide the jump start many seek with that morning cup of coffee.
Disorders associated with caffeine use include Caffeinism – a clinical syndrome characterized by anxiety, agitation, insomnia and mood changes. Symptoms include tachycardia, hypertension, cardiac arrhythmias, and gastrointestinal disturbances.
People with anxiety disorders tend to be quite sensitive to the effects of caffeine, especially if they do not develop a tolerance to caffeine’s effects.
Source: Julien, Robert M. A Primer of Drug Action Tenth Edition
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