I did a little reading up on caffeine and ADHD and found mixed opinions.
From American Psychological Association: A sip into dangerous territory
Caffeine certainly yields both physical and emotional modifications in children; but is every change for the worst?
Marjorie Roth Leon, PhD, of National-Louis University, thinks not. She performed an aggregate analysis of 19 empirical studies examining the effects of caffeine on aspects of cognitive, psychomotor, and emotional functioning among children with attention-deficit hyperactivity disorder (ADHD). Traditional treatments, such as the stimulant drugs methylphenidate and amphetamine, outperformed caffeine in improving functioning and reducing levels of hyperactivity. However, says Leon, "compared to giving children with ADHD no treatment whatsoever, caffeine appears to have potential to improve their functioning in the areas of improved parent and teacher perceptions of their behavior, reduced levels of aggression, impulsiveness and hyperactivity, and improved levels of executive functioning and planning."
Leon believes caffeine's positive effects are not limited to children with ADHD in terms of curbing aggressiveness.
"Caffeine decreases explosiveness in children who have ADHD, and similarly increases feelings of calm in people who do not have ADHD," she says.
But when faced with the task of finding caffeine's benefits for normal children, she encountered obstacles. Teachers did not mark any behavior improvements following caffeine ingestion. Furthermore, "children without ADHD experience an increased feeling of restlessness and have faster simple reaction times" with caffeine, says Leon. And while caffeine calms and uplifts ADHD children, the substance can have adverse effects on normal children's levels of anxiety and happiness.
From Healthline: The 'ADHD Diet': What Works and What Doesn’t
Can Caffeine Treat ADHD?
ADHD is characterized by lack of focus, the inability to sustain attention and, of course, hyperactivity. So it’s a bit of a paradox that the most common—and effective—treatments for the disorder are stimulants. The go-to prescription drug, methylphenidate (Ritalin), is a potent central nervous system stimulant, which has the opposite effect in people with ADHD; it enables them to remain relatively calm and focused. So it should come as no surprise that some experts suggest caffeine for the treatment of ADHD symptoms.
Caffeine is a natural stimulant found in coffee, tea, and cocoa. In most individuals, it has been shown to increase alertness and reduce fatigue, while also improving vigilance during tasks that require sustained attention. Emerging research suggests that caffeine may also be a useful supplement for children and adults with ADHD.
From the Journal of the American Academy of Pediatrics: Health Effects of Energy Drinks on Children, Adolescents, and Young Adults
Energy drinks have no therapeutic benefit, and many ingredients are understudied and not regulated. The known and unknown pharmacology of agents included in such drinks, combined with reports of toxicity, raises concern for potentially serious adverse effects in association with energy drink use. In the short-term, pediatricians need to be aware of the possible effects of energy drinks in vulnerable populations and screen for consumption to educate families. Long-term research should aim to understand the effects in at-risk populations. Toxicity surveillance should be improved, and regulations of energy drink sales and consumption should be based on appropriate research.