Fascinating point about caffeine as a methylxanthine. My experience with caffeine is that it can help kickstart me into doing something I have been putting off, but easily overcompensates by making me start too many things at once and thereby worsening symptoms of ADD.
Yeah, that's the same story with me. Normally I don't even consume caffeine for that reason.
On the occasions I do have it and attempt to accomplish something that requires focus, it elevates energy but worsens focus considerably, even in minute amounts. It's at best a fun way to spin my tires, and at worst the harbinger of productivity destruction.
I suspect this is related to caffeine's dopaminergic action (dopamine regulates anticipatory training): https://en.wikipedia.org/wiki/Caffeine#Effects_on_striatal_d...