Individuals with ADHD often use stimulants like coffee, which may be an attempt at self-medication.

“All of those substances that I just described in particular cocaine and amphetamine, but also coffee and cigarettes increase levels of multiple neurotransmitters, but all have the quality of increasing levels of dopamine in the brain and in particular, in the regions of the brain that regulate attention and these task related and default mode networks okay?”

“all of them have relayed the fact that many people not just young people but adults with ADHD will often use not necessarily abuse but will use stimulants like coffee and other forms of stimulants to a high degree and then of course you can say well perhaps the stimulants are causing ADHD but they actually argue for the opposite which is that people are attempting to self-medicate”

“So if you think back before, you've got this default mode network and a task related network and they need to be in this kind of concert of anti-correlation and in ADHD they're firing together. Well, the problem seems to be that when dopamine is low, neurons fire more than they should in these networks that govern attention. This is the so-called low dopamine hypothesis. And if you start looking anecdotally at what people with ADHD have done for decades, what you find is that they tend to use recreational drugs or they tend to indulge in non-drug stimulants. So things like smoking a half a pack of cigarettes and drinking four cups of coffee a day. or if the person had access to it, using cocaine as a recreational drug or amphetamine as a recreational drug.”