Caffeine shown to affect dopamine function in patients with Parkinson's disease (medicalxpress.com)

I will use caffeine when I need it for a few days and then cut all consumption. I find that it helps me focus and causes a slight euphoric effect when taken in moderation. If I take it for long periods of time, I end up getting major anxiety.

I didn't realize until I was much older. In high school, I would drink 2-liters of Mountain Dew/day and had major anxiety issues.

May explained why it's easier to avoid distractions when I'm using caffeine.