Caffeine: the most popular and well known psychoactive drug. It’s commonly found in coffee, tea, energy drinks, soft drinks and even chocolate. Caffeine seems to have acute cognitive effects. It seems to be able to consistently increase alertness and attention. But whether these effects go away with regular use is still a matter of debate. Caffeine exerts its effects by blocking adenosine receptors A1 and A2A. The effects from the blockade of A1 receptors seems to deminish with chronic exposure, but there may be residual effects that are mediated through A2A receptors. Routine moderate caffeine consumption seems to be associated with many positive outcomes including a decreased risk of parkinson’s disease, alzheimer’s disease, depression, cardiovascular disease and strokes. Interestingly, in one study there seemed to be a relationship between extroverted personalities, caffeine intake and enhanced performance on challenging working memory tasks.