In theory and in animal model, caffeine intake is effective in ADHD treatment. In practice, research studies show they are associated but a causal link is not yet found.
Effectiveness in Theory and in Animal Model
It is generally accepted that an underlying cause of attention deficit hyperactivity disorder (ADHD) is an energetic dysfunction, and children with ADHD are commonly treated with stimulant medications to raise their arousal level.
Much like psychostimulant medications that are used to treat ADHD, foods, beverages, and supplements containing caffeine (and tobacco products containing nicotine) are thought to play a role in compensating for lower levels of mental arousal and to enhance cognitive performance among ADHD-affected individuals.
Epidemiological studies have pointed out that the incidence of ADHD is lower in countries with greater average consumption of caffeine. And although it has not yet been tested if caffeine is effective in alleviating cognitive disturbances in ADHD patients, promising positive results were obtained using an animal model of ADHD - spontaneous hypertensive rats (SHR).
For instance, in an SHR animal study, researchers found that caffeine plus exercise was able to reverse olfactory impairment observed in SHR animals. In addition, chronic caffeine intake and voluntary exercise independently improved short-term recognition memory performance.
Studies Show Association but not Causality
In a 2010 study, a total of 448 adolescents and young adults between the ages of 13 and 21 years were recruited in a study of the effects of caffeine on ADHD. The participants were surveyed for their use of caffeinated beverages such as coffee, tea, cola, etc.
This study found that adolescents with ADHD were nearly twice as likely to use more caffeine than were adolescents without ADHD.
However, the best that researchers could conclude is that there is an association between caffeine and ADHD. Whether this is cause or consequence of their ADHD, confined to beverages, or applies equally to other food (e.g., chocolate) and non-food sources of caffeine (e.g., herbal supplements and nonprescription medications) cannot be answered by this study.
In a 2020 study of 302 adolescents (ages 12-14), researchers also found that adolescents with ADHD were 2.47 times more likely to consume caffeine in the afternoon and evening than adolescents without ADHD.
It is interesting to note that, in comparison with adolescents without ADHD, adolescents with ADHD consume more caffeinated beverages in the afternoon and evening than in the morning. Researchers say that the afternoon is likely a time where teens’ caffeine consumption is not directly supervised by parents.
Further, the afternoon and evening are times of day when there are high demands to pay attention, such as during class or while completing homework. Adolescents with ADHD struggle with sustained attention and may be more likely to turn to caffeine use to increase attention in the afternoon and evening hours.
Although a direct causal link cannot be established, these study results raise questions about the function caffeine serves in this population. Researchers say that caffeine may play a role in increasing the effect of prescription stimulants for the treatment of ADHD.
Liu, Kezhi, et al. “Tea consumption maybe an effective active treatment for adult attention deficit hyperactivity disorder (ADHD).” Medical Hypotheses, vol. 76, 2011, pp. 461–463.
Walker, Leslie R., et al. “Adolescent Caffeine Use, ADHD, and Cigarette Smoking.” Children’s Health Care, vol. 39, 2010, pp. 73–90.
Cusick, Caroline N., et al. “Caffeine Use and Associations with Sleep in Adolescents With and Without ADHD.” Journal of Pediatric Psychology, vol. 45, no. 6, 2020, pp. 643–653.
França, Angela Patricia, et al. “Caffeine Consumption plus Physical Exercise Improves Behavioral Impairments and Stimulates Neuroplasticity in Spontaneously Hypertensive Rats (SHR): An Animal Model of Attention Deficit Hyperactivity Disorder.” Molecular Neurobiology, vol. 57, 2020, pp. 3902–3919.