To examine this question, we need to first think about what causes ADHD. Most scientists think that inadequate levels of brain chemicals, known as the neurotransmitters dopamine and serotonin, are to blame for ADHD…these chemicals don’t spend enough time between the brain cells to perform their work but instead get sucked back into the next brain cell too quickly. (For the dietitians and other healthcare professionals or scientists reading this, this means that dopamine and serotonin receptors on each neuron don’t allow those neurotransmitters to spend enough time in the pre-synaptic space.) This altered brain metabolism leads to the hallmark signs of ADHD: inattention, hyperactivity, and impulsivity. Although it seems counterintuitive to give a stimulant medications like methylphenidate (Ritalin) to a hyperactive person, these medications beneficially stimulate brain activity by increasing the dopamine and serotonin activity.
Therefore, anything that stimulates dopamine or serotonin can help improve the symptoms of ADHD, especially inattention. Sugar is known to increase dopamine – this is our “feel good” chemical, which is why sugary foods and beverages are so appealing to us! The problem with sugar intake is that the increase in dopamine activity is very short lived, so sugar is not an effective treatment for ADHD. It is unhealthy for many other reasons, so I don’t recommend consuming sugary foods or drinks on a regular basis.
Caffeine is known to increase mental alertness, so it is also not surprising that this would be linked to improvement in the ADHD symptom of inattention. However, there have been very few studies in humans to confirm this hypothesis because most studies for ADHD are done with children – and it’s not very ethical to give children a lot of caffeine just for the purpose of studying its effects!
Here is a summary of two studies that have been done:
Study: Barry, Christopher, & Sloman; 1981
Results: 6 children with ADHD treated as day hospital patients; Low dose caffeine with low dose methylphenidate had the better treatment effect compared with methylphenidate by itself or methylphenidate + high dose caffeine.
Study: Walker, Abraham, & Tercyak; 2010
Results: Adolescents with ADHD were two times more likely to drink caffeinated beverages.
The 1981 study is (obviously) very old, and completed with a very small sample size. It did show that children should not consume excess caffeine if taking stimulant medications, but it did not study the effect of caffeine without medications. The 2010 study confirmed what the teenagers I work with tell me: adolescents are likely to self-medicate with caffeine. However, this does not tell us whether or not caffeine improves ADHD symptoms or reduces dependence on medications.
Bottom Line: Drinking sugar sweetened, high caffeine beverages is not likely to show sustained improvements in ADHD symptoms, and can lead to other health risks. It is best to work with a doctor and registered dietitian to determine a medication, behavioral, and nutrition plan that improves ADHD symptoms and promotes a healthy lifestyle.
References
1. Barry DG, Christopher DW, Sloman L. Responses to methylphenidate and varied doses of caffeine in children with ADHD. Canadian J Psychiatry. 1981;26:
2. Walker LR, Abraham AA, Tercyak KP. Adolescent caffeine use, ADHD, and cigarette smoking. Children’s Health Care. 2010;39:73-90.