Children’s caffeine intake linked to brain differences and poorer mental health

According to a new observational study, young caffeine consumers, primarily from soft drinks, report poorer mental health and show lower surface area across the brain’s outer layer, which is involved in cognitive processing, decision-making, attention, and emotions, among other important functions. 

The study from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London in the UK analyzed data from 9,632 children participating in the Adolescent Brain Cognitive Development (ABCD) Study.

The researchers correlated mild caffeine intake — one drink per week — with lower cortical surface area and less sleep. They suggest that shorter sleeps associated with caffeine consumption is linked to mental health issues that develop over time.

“Caffeine is such a normal part of daily life that it's easy to forget young people are consuming it too,” comments Dr. Divyangana Rakesh, senior author of the study from the IoPPN. 

“Studies have found that two-thirds of adolescents consume caffeine at least once a week. Despite it being a psychoactive substance, it is completely unregulated.”

Brain and mental health impacts

The ABCD study followed the brain development of young people aged nine to 11 across the US. The children reported how many caffeinated drinks they usually consumed weekly and parents reported how long the children slept on average. MRI scans measured the children’s cortical thickness and surface area, the brain’s folded outer layer.

After six and 18 months, the children reported back on their mental health. The researchers noted increased caffeine consumption linked to lower surface area across the cortex, despite adjusting for household socioeconomic circumstances such as parental educational attainment and income.

The researchers examined what connects caffeine to brain structure differences and found that shorter sleep was linked to lower surface area. This shorter sleep and lower surface area link partly explained the association between higher caffeine and more mental health issues six and 18 months later. Examples of problems include attention, mood, and behavior. 

Focus on soft drinks

According to the Biological Psychiatry: Cognitive Neuroscience and Neuroimaging study, higher caffeine intake was associated with lower total cortical surface area and lower surface area — present in 22 different regions — across all four lobes of the brain. The publication highlights that soft drinks were the biggest source of caffeine in the study.

“We found that even fairly low levels of intake were linked to small differences in brain structure and later mental health, and lower sleep duration seems to be an important underlying link,” says Rakesh. 

“Although we cannot comment on causality, our results do suggest that both caffeine intake, including from soft drinks, and sleep are worth paying attention to when we think about young people's mental health.”

The researchers underline that differences in overall brain surface area emerged at just one caffeinated drink a week, compared with none.

“Soft drinks contain a lot of sugar and often go hand in hand with less healthy lifestyle habits and more risk-taking behaviors, so we can't yet separate the role of caffeine from everything else that comes with them,” says Jiayi Zheng, first author of the study from the IoPPN at King’s College London.

“That’s the next question we want to answer, ideally with more precise measures of what young people drink, when they drink it, and how well they sleep.”