Chronic caffeine ingestion causes microglia activation, but not proliferation in the healthy brain.

Caffeine is the most popular psychoactive drug in the world which contributes to behavioral and metabolic changes when ingested. Within the central nervous system (CNS), caffeine has a high affinity for A1 and A2a adenosine receptors. Serving as an antagonist, caffeine affects the ability of adenosine to bind to these receptors.