Can but in my experience, most ADHD-affected persons will self-medicate with caffeine in atleast low doses.

Working from home, I drink about four coffees through the morning and early afternoon, plus one later in the day once the others have worn off, if I feel like it.

I drink half-caff double shots (sounds odd but I want a decent amount of flavor but not too much caffeine), making macchiato first thing in the morning, americano later.

People laugh at how I’m always carrying a coffee when I’m working. I tell them I’m just keeping my caffeine at the perfect level, which is true.

I took amphetamines daily (week-daily at least) on and off for a decade before my diagnosis and the realisation that I was medicating with it was a large part of seeking my diagnosis. For me speed was calming and focussing and a tool to help me manage my life, not a fun thing for going out.

What a lot of people probably don't realize is that stimulants like Coffee (or even Speed) depend on the brain's structure. ADHD Brains work differently and they respond different to stimulants. And people don't like it when ADHD people self-medicate with coffee because they think it would make it worse (Heck, I've gotten detention for consuming coffee because I had ADHD. "Concerned teachers" they called it).

It’s a nightmare when dealing with doctors.

Another example, Benadryl makes me insanely hyper. One of my kids is same way.

Telling a doctor results in being labeled a liar.

At least a dozen medications that I respond in weird ways to.

A 4 hour adderall (20mg), lasts me about 30 hours.

I will add my anecdote to the mix. I previously consumed caffeine in the form of soda for many, many years. I quit soda cold turkey two months ago after a mild but particularly meaningful magic mushroom experience, and coupled with the regular mushroom experiences my focus control has been better than ever (but still extremely difficult, just enough less so that I can tell the difference).

Sometimes makes it a lot better, sometimes worse.

Worked better when younger. Now it’s role as a vascular-constrictor is dangerous for me.