The trend among younger children to frequently drink caffeinated soda may indicate a higher risk of alcohol consumption in the future, new research suggests.

In a study of over 2,000 US children, aged between just nine to 10, those who reported drinking caffeinated soda daily were found a year later twice as likely to state they had sipped alcohol.

Published in the peer-reviewed journal Substance Use & Misuse, the results of the study also demonstrate that daily drinkers of caffeinated soda were more impulsive and had poorer working memory.

Although strong associations between caffeinated beverage consumption and future substance use have been well documented in adolescents and adults, the findings are the first to demonstrate similar results in young children.

In teenagers, previous research has shown that those regularly drinking energy drinks are five times more likely to use alcohol or marijuana within one to two years.

"Our findings suggest that daily consumption of caffeinated soda in children is predictive of substance use in the near future. One possible explanation is that the substances contained in caffeinated soda (caffeine and sugar) could induce a toxicological effect on the brain, making the individual more sensitive to the reinforcing effects of harder drugs like alcohol," said lead author Mina Kwon, from the Department of Psychology at Seoul National University.

To test cognitive functions, the children were given a series of tasks to do while their brain activity was recorded.

For example, in one task, participants had to determine whether an object presented to them was the same as that shown in the two preceding trials. The results showed that both high impulsivity and low working memory were significantly associated with daily caffeinated soda consumption.

Interestingly, children who regularly drank caffeinated soda also showed distinct brain activity compared to their non-drinking peers.

For example, when performing the impulse control task, daily drinkers showed lower activity in a brain region called the anterior cingulate cortex (ACC). Reduced activity in the ACC is frequently observed in children with attention deficit hyperactivity disorder (ADHD) and individuals with substance use disorders.

Meanwhile, in the working memory test, daily drinkers showed less activation in a brain region called the inferior frontal gyrus (IFG), which is a part of the frontal lobe. Prior studies have shown that reduced activation in the frontal cortex is related to lower working memory capacity.

Taken together, the findings strongly suggest an association between daily soda consumption low working memory and high impulsivity, which are themselves recognised as risk factors for substance use disorders.