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Sugar-sweetened beverages are one of the major culprits in the obesity epidemic, but sodas have also been connected to behavioral problems among teens. That link apparently extends to young kids as well.

Among children 5 years old, according to the latest research, those drinking more sugar-sweetened sodas showed increased aggression, withdrawal and difficulty paying attention than those drinking fewer or none of the beverages.

(MORE: How Sweet Can Become Toxic)

It’s the first time that the effects of sugared beverages have been traced to behavior issues among children so young. But the findings mirror similar trends among adolescents; a 2011 study published in the journal Injury Prevention found that teens who drank more than five cans of soft drinks every week were significantly more likely to have carried a weapon and acted violently toward peers, family members and dates. Another study from the same authors reported that high consumption of soft drinks was associated with a range of aggressive or mood-related behaviors, from fighting, feeling sad or hopeless to even being suicidal.

In the latest study, published in the Journal of Pediatrics, parents reported that 43% of the 5-year olds participating in the Fragile Families and Child Wellbeing Study drank at least one serving of soda every day, and 4% consumed four or more servings daily.

In order to evaluate the relationship between the sugared drinks and behavior problems, the researchers adjusted for several factors that can influence behavior, including their mothers’ depression and the children’s diets. Even after this adjustment, the scientists found a significant relationship between more soda consumption and aggressive behaviors that included destroying other people’s belongings, getting into fights and physically attacking others.

What makes soda-drinking kids so unruly? “Soft drinks are highly processed products containing carbonated water, high-fructose corn syrup, aspartame, sodium benzoate, phosphoric or citric acid, and often caffeine, any of which might affect behavior,” the authors write.

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Caffeine is a likely culprit, since other studies connected the compound with changes in hormone levels that could alter the way still developing brains perceive and evaluate risk. Because caffeine can act on so many brain systems, but there is still little information on its influence on young children, the FDA is currently investigating the safety of caffeine that is added to food products consumed by kids and adolescents, like drinks, chips and even gum.

The sugar in sodas may also affect behavior, though that connection is murkier. A recent study reported that even at doses considered average for human consumption — about four cans of soda in a day — sugar has toxic effects in mice, impairing their ability to establish territories and reproduce. “There are too many unknown variables to say whether or not sugar causes aggression,” says Judy Caplan, a registered dietitian nutritionist for the Academy of Nutrition and Dietetics. “I think more studies like this are needed to really understand what role food (sugar) plays in aggression in children. We will have to see what the future confirms.”

While the beverage industry has taken steps to limit children’s access to sugared soft drinks — providing healthier options such as water, fruit juices and skim milk in schools instead–the study highlights how prevalent soda consumption is in the U.S. — even among the very young. According to an American Beverage Association spokesperson, member companies do not promote or market the consumption of soft drinks to children in the age group examined in the study, but so far the high consumption among kids doesn’t seem to help them establish and maintain healthy relationships with friends and family.