Attention Deficit and Hyperactivity Disorder, or ADHD is a condition in which a person is unable to control behavior due to difficulty in processing neural stimuli, accompanied by an extremely high level of motor activity. ADHD affects both children and adults, but is more commonly diagnosed in childhood, as it is often prominently displayed during childhood1.
ADHD has three main categories; hyperactivity, impulsivity, and attention deficit. A person with ADHD may predominantly suffer in one category, or a mixture of the three.
Impact of coffee and caffeine on Attention Deficit and Hyperactivity Disorder
Those with ADHD have a different brain chemistry to those without, and this can change the effects coffee will have. Caffeine can cause sleep disturbances in both ADHD suffers and non-sufferers. Sleep disturbances cause ADHD like effects, such as irritability, forgetfulness, trouble focusing or sitting still, and difficulty controlling emotions. As those with ADHD already suffer from these symptoms, sleep deprivation caused by caffeine will exacerbate these symptoms. Therefore, coffee should not be drunk by ADHD sufferers at any time that will affect sleep, i.e. the evening.
Although coffee has a disrupting effect on sleep, caffeine has some very beneficial impacts on those with ADHD. Caffeine is a vasoconstrictor, which means it causes blood vessels to narrow, reducing blood flow. Amphetamines, which are often used to treat ADHD (such as Adderall) are also vasoconstrictors. Caffeine therefore imitates the effect of ADHD medications. It is not known why vasoconstriction is beneficial to those with ADHD, but it is thought that reducing blood flow will reduce activity in regions of the brain that are overactive, allowing them to function and cooperate better with the rest of the brain.
Individuals with ADHD also tend to have low dopamine levels. Low dopamine levels cause difficulty focusing and concentrating. Stimulant chemicals such as caffeine or amphetamines raise dopamine levels. This is another example where caffeine imitates the effect of prescription medications for ADHD. For non-ADHD sufferers, stimulants will raise dopamine levels too high, causing anxiety and agitation. For ADHD sufferers, stimulants can raise dopamine levels to the perfect level.
There are two things that are important to note;
Firstly, when caffeine and stimulant ADHD medicines (like amphetamines or methylphenidate) are combined, they create an effect called synergy. This occurs when two drugs have additive mechanisms of action, making their combined effect more powerful. This means medications would have a stronger effect, and also stronger side effects.
Secondly, caffeine is not as effective as prescription medication. To reach similar effects as amphetamines, a lot of coffee would have to be drunk. Mayo clinic defines heavy caffeine use as four or more cups a day, or 500-600mg. A caffeine overdose comes with side effects, such as sleeplessness, rapid heartbeat, anxiety, muscle shakes, stomach upset. So while caffeine has been shown to have positive impacts on ADHD, it should be used as a treatment with great caution, especially when used alongside prescription medications.2