But caffeine is also a stimulant that influences neurotransmitters such as dopamine—which raises the question: Could ingesting caffeine in the form of coffee, tea, or any other source be a safe way to help alleviate ADHD symptoms, or would it just make things worse? And is combining caffeine with ADHD medication even OK, or is it potentially dangerous? Caffeine predominantly does this by acting as an adenosine receptor antagonist. Caffeine is similar in structure to adenosine, a chemical that binds to receptors in the brain and subsequently slows down the activity of neurons that produce attention-boosting neurotransmitters like dopamine. This has the effect of making us sleepy and less able to maintain focus. But when we consume coffee, tea, or energy drinks, caffeine binds to these receptors instead, which minimizes the impact of adenosine and thereby curbs its effects by indirectly increasing dopamine release2. This is why caffeine in moderation can have positive effects on focus, attention, and energy. However, too much caffeine can lead to problematic side effects such as restlessness, elevated anxiety, rapid heartbeat, insomnia, headaches, dependency, cortisol and adrenal disruption, and more. “Stimulant medications for ADHD work to increase the amount of the neurotransmitter dopamine in the brain by slowing down its reabsorption, thus promoting increased focus,” says Uma Naidoo, M.D., a Harvard-trained nutritional psychiatrist and author of This Is Your Brain on Food. “Therefore, consuming stimulating substances like caffeine can have similar effects on those with ADHD. Modest amounts of caffeine have been shown to help improve focus, stimulate the mind, and clear brain fog. Individuals with ADHD benefit from this form of a ‘brain boost’ as it helps them to focus on completing each task at hand.” Other experts agree that it may be effective, particularly if ADHD symptoms aren’t too severe. “It can be an effective option for mild ADHD, especially if the person is not having negative side effects such as GI symptoms, cardiac symptoms, or sleep disruption,” says Lidia Zylowska, M.D., a psychiatrist at the University of Minnesota Medical School and author of The Mindfulness Prescription for Adult ADHD. Research in the area of caffeine and ADHD is not robust enough to be conclusive—most has been done on animals or children, and some studies are quite old. But overall, it shows promise, and some experts have called for additional investigation4 into caffeine’s potential therapeutic effect. Here’s a sampling of the research to date: If you don’t tolerate caffeine, or if you abuse it, it could potentially make your ADHD symptoms worse. This is particularly true if you suffer from anxiety, which can be negatively affected by excessive caffeine consumption, and which happens to affect about 50% of adults8 with ADHD. Additionally, if your caffeine consumption interferes with sleep, it will likely cancel out any potential focus-enhancing benefits. “Especially if consumed later in the day, the stimulating effects of caffeine can prevent us from falling and staying soundly asleep, which can exacerbate feelings of brain fog and lack of focus during the day,” says Naidoo. In a 2020 study9, the combination of L-theanine and caffeine not only helped to improve the focus of boys with ADHD and reduce mind wandering but also improved their inhibitory control and prevented rash behavior. While both caffeine and L-theanine demonstrated cognitive benefits individually, the combination was even better at alleviating these ADHD symptoms. Green tea, including matcha, generally has the highest levels10 of L-theanine, along with moderate amounts of caffeine. But, because both are stimulants, we do know that combining caffeine and ADHD medications “can potentially put someone at risk for having more serious side effects such as cardiac overstimulation,” says Zylowska. “However, some patients combine caffeine with medications and are able to tolerate it well—it often depends on the dose of each.” According to Zylowska, some people may space out caffeine and stimulant medication—for example, relying on a morning cup of espresso to get going and using their stimulant medication later in the day. “Many patients also spontaneously decrease the use of caffeine as they start stimulant medications,” she says. “But if they don’t, it is really important to monitor for the synergistic side effects.” (This refers to the fact that caffeine and stimulant medications have a synergistic effect that increases the other’s effectiveness, which could potentially increase problematic side effects.) For a generally healthy person, consumption of up to 400 mg of caffeine per day is generally safe and tolerable. But this may need to be much lower depending on your personal tolerance and whether or not you are taking medication. (Check out this handy guide to caffeine levels in nine popular drinks.) Also, if you’re pregnant or lactating, please speak with your doctor about how much caffeine is appropriate for you at all times. The way caffeine affects you personally will depend on a variety of factors such as your personal tolerance, whether you have another health condition such as anxiety or cardiovascular issues, whether you’re getting enough sleep, and whether you’re taking stimulant medication.
