Caffeine

Caffeine acts as an adenosine-receptor antagonist. This means that it binds to these same receptors, but without reducing neural activity. Fewer receptors are thus available to the natural “braking” action of adenosine, and neural activity therefore speeds up (see animation).

adenosine receptors - THE BRAIN FROM TOP TO BOTTOM

(Google)

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Caffeine works for some with ADHD;  food additives in FDA approved medicines and foods need better ingredient labels.

- C. Thomas Wild (1981, 2020)