Caffeine in children: Researchers find changes in the brain
Even small amounts of caffeine per week are associated with sleep deprivation and brain abnormalities in children. Researchers suspect this may be a risk factor for future behavioral problems. Why there is no reason to panic, however.
A sip of cola or soda here, a glass of iced tea there – while there would be a huge outcry if parents served their children a cup of coffee in the morning, caffeine sneaks into (children's) everyday life almost unnoticed via sugary drinks. A little caffeine won't hurt, after all, it's not a double espresso. But a child's brain is not just a smaller version of an adult's and reacts significantly more sensitively to the psychoactive substance.
A research team from King's College London now shows, based on extensive US longitudinal data, that even small amounts of caffeine are associated with measurable differences in the brain development of nine- to eleven-year-olds.
Striking patterns in almost 10,000 children
For the study, the team led by Jiayi Zheng and Dr. Divyangana Rakesh from King's College London used data from 9,632 children from the so-called ABCD study (Adolescent Brain Cognitive Development) – the largest US longitudinal study on brain development in adolescence. In addition to self-reports on weekly consumption of soft drinks, tea, or coffee, the researchers analyzed high-resolution MRI brain scans as well as information from parents about their children's sleep duration.
The result: Children who drank more caffeine had an overall smaller cerebral cortex surface (cortical surface). The effect was seen in 22 regions across all four lobes of the brain – exactly where impulse control, attention, and emotions are processed.
Even one serving per week is enough
What is particularly surprising is the small amount. The abnormalities in the brain were measurable from as little as a single caffeinated drink per week. Senior author Dr. Rakesh sees this as a clear indication that we significantly underestimate caffeine in the everyday lives of young people:
«Caffeine is such a normal part of our daily lives that it is easy to forget that young people consume it too. Studies show that two-thirds of adolescents consume caffeine at least once a week. Although it is a psychoactive substance, it is completely unregulated.»
Why the brain needs a good night's sleep
Biologically, the mechanism is quickly identified. Caffeine occupies the exact receptors in the brain where the neurotransmitter adenosine would otherwise dock to signal fatigue. The body simply does not realize how exhausted it is and that it should actually be sleeping. In the children studied, this also led to shorter sleep times in reality.
Lack of sleep is tricky for developing brains. At night, the brain sorts synapses, prunes unused connections, and strengthens neural pathways. If this recovery is missing, remodeling processes stall. The research team therefore did not stop at the MRI scan but interviewed the children again six and eighteen months later about their well-being. A recurring pattern emerged: shorter sleep times and smaller brain surfaces were linked to more anxiety, depressive moods, and impulsivity later on.
Caffeine or simply too much sugar?
This all sounds quite dramatic, but as is often the case in research, we must clearly distinguish between causality and correlation. The researchers did not prove that caffeine directly triggers mental health problems, but merely identified a statistical link between consumption and these outcomes.
Furthermore, the children studied consumed their caffeine almost exclusively through sweetened soft drinks like cola. This automatically brings a second suspect into play: sugar. High amounts of sugar can also influence neural connectivity through inflammatory processes and metabolic reactions. Whether the caffeine molecule was actually noticeable in the brain or simply the side effects of too much soda cannot be clearly separated in an observational study. Lead author Zheng therefore cautiously contextualizes the result:
«Soft drinks contain a lot of sugar and often go hand in hand with less healthy lifestyle habits and riskier behavior. We therefore cannot yet separate the role of caffeine from everything else that comes with it.»
It is possible that children who drink a lot of cola sleep worse because they sit in front of screens longer in the evening or have a less balanced diet overall. The study provides no reason for panic. It is, however, a solid reminder that caffeine is not a harmless thirst quencher for children.
Science editor and biologist. I love animals and am fascinated by plants, their abilities and everything you can do with them. That's why my favourite place is always the outdoors - somewhere in nature, preferably in my wild garden.
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