ADHD and Caffeine
Caffeine is a central nervous system stimulant that can increase alertness and improve cognitive performance. It displaces the neurotransmitter adenosine, which is responsible for feelings of sleepiness that accumulate across the day, and it increases norepinephrine and dopamine availability in the brain. These are the primary neurotransmitters implicated in ADHD. Most adults use caffeine at least once a day for its alerting properties. Many people with ADHD use caffeine to help manage their symptoms, whether they know they have ADHD or not. After all, it's cheap, legal, readily available and socially acceptable to drink caffeinated beverages - which is how most caffeine is consumed.
I see high caffeine consumption often in my assessment clients. One was drinking twelve cups of coffee a day. This dropped to two cups a day after they started stimulant meds. They simply didn't feel the need for coffee like they used to. They felt adequately stimulated already. Plus, ingesting too much caffeine when you're already taking a stimulant medication can lead to unpleasant symptoms like jitteriness, a feeling of tension, anxiety, and even panic attacks (and it can be worse if the person forgets to eat - which is more common with ADHD and when on stimulant medication). These unpleasant consequences place natural limits on how much caffeine a person will consume.
Click here for information about caffeine and a list of the caffeine content of different beverages.
Caffeine's effects in the brain can become apparent in as little as five minutes after consumption, with a peak around 30 minutes later, and a duration of up to 60 minutes. That's a much faster onset, peak, and duration than short-acting stimulant medication, which takes around 30 minutes to onset, peaks soon after, and lasts for around 3-4 hours.
Such a short peak for caffeine is obviously not going to be a great treatment for ADHD, so you can see why someone might drink twelve cups of coffee a day! In addition, it is easy to build a tolerance for caffeine, especially if it is consumed around the same time each day, and it is quite possible to experience dependence, as evidenced by unpleasant withdrawal effects when it is stopped abruptly.
Do you know someone who can drink a caffeinated beverage and fall asleep right after? For most people, caffeine causes problems with sleep onset and poorer quality sleep. Caffeine has quite a long half-life meaning that an afternoon coffee can disrupt the sleep of many people for around 12 hours, and many people choose not to drink coffee after midday. I have met several clients with ADHD who can drink coffee right before bed. And likewise, there are people with ADHD for whom stimulant medication does not delay sleep, but for whom it helps them to get to sleep. While I am not sure of the mechanism of action here, I suspect it has to do with a calming effect and allowing the person to relax as is necessary for sleep. I wonder if those with ADHD who find stimulants to help with falling asleep also have poorer quality sleep due to it. I can't find any information about this. That would be a worthwhile experiment.
Click here if you want to go on a deep dive about caffeine with neuroscientist Dr Andrew Huberman. Dr Huberman's podcast series is also available on streaming services (there's even a good one about ADHD).