Children today drink twice as much soda as they did 20 years ago, averaging as much as 20 ounces a day. Quenching that thirst for pop often comes with a price tag of 100 mg of caffeine, well beyond the threshold for detecting mood-altering and behaviorally active effects. Some children and adolescents then top off that daily cola intake with coffee drinks--the iced cappuccinos and "caffeine blasts" so popular in today's café scene.

The impact of so much caffeine intake among children, say many psychologists, has been too long ignored.

"Caffeine can stimulate immature neurological systems beyond children's ability to tolerate it, which can have serious effects," says APA Div. 43 (Family) President Terence Patterson, EdD, of the University of San Francisco. "Excessive caffeine use damages the attention capacity that children need to cooperate in play, family and school environments."

Leading caffeine researcher Roland Griffiths, PhD, of Johns Hopkins University, deems the drug the most widely used mood-altering drug in the world, with usage far exceeding that of alcohol and nicotine.

"Research has shown that the dose of caffeine delivered in a single can of soft drink is sufficient to produce mood and behavioral effects," he says. "Children who haphazardly consume caffeine are at risk for going through alternating cycles of withdrawal and stimulation."

To date, few studies have explored caffeine's physical effects on children and even less attention has been paid to the drug's psychological consequences. But researchers are now beginning to delve into the field.

So far, they agree that because caffeine's effects are dependent on body weight, the drug packs a more powerful punch for children, giving them an amplified version of the alertness, anxiety, nervousness and insomnia it may produce among adults. And they are troubled that the favorite beverages among American youth are those high in caffeine and sugar, instead of calcium and vitamin C.

What we know

John Greden, MD, head of psychiatry at the University of Michigan, cites many reasons to curb children's caffeine consumption. He has identified symptoms--agitation, disorientation, nervousness, twitching, recurrent headaches and gastrointestinal disturbances--which some researchers dub "caffeinism" and can be mistaken for anxiety neuroses.

Johns Hopkins' Griffiths says that adults may ignore children's caffeine consumption because the drug poses no life-threatening health risks and adults are familiar with its effects. But, he says, caffeine use among children is more complex because kids are less likely to be aware of how caffeine really affects them. So too, the cycle of dependence and withdrawal can be exacerbated for youths who depend upon their parents or schools for beverages and are thus unable to protect the continuity of their caffeine supply.

Griffiths has conducted and reviewed several studies showing that caffeine can produce many features of addiction in the manner of classic drugs of abuse, but at milder levels. Thirty percent of caffeine consumers fulfill DSM-IV diagnostic criteria for a drug dependence syndrome--including tolerance, withdrawal, desire to quit, and continued use despite having medical or psychological problems with caffeine. Studies have confirmed withdrawal and the dependence syndrome in children and adolescents.

One such study compared the mood ratings of 11- and 12-year-old children on low and high caffeine intakes over two successive days. On the second day, the children abstained from caffeine, and during withdrawal the low consumption group reported having more energy, lucid thinking and feelings of happiness, health and general well-being than the high consumption group, which reported difficulty thinking clearly and feelings of anger.

Griffiths' plea, as both a researcher and a parent, is for "an intelligent use of caffeine, with the most fundamental message being that caffeine really is a drug, and should be accorded respect as such."

The ADHD connection

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.

It is this exact "case of the jitters" that prompts some researchers to ask if children's caffeine abuse could be a harbinger of ADHD. Mark Stein, PhD, of Children's Hospital in Washington, D.C., researches the connection between caffeine and ADHD. Stein suggests that caffeine and ADHD may be related through their effects on sleep. Although their symptoms differ, he says, "caffeine is a stimulant that affects sleep, and chronic sleep deprivation can cause inattention, and potentially could be ADHD."

In regards to the consequences of moderate caffeine upon children's behavior, however, Stein has yet to raise any red flags. Ten years ago, he conducted a meta-analysis of theophylline, an oral drug used to treat asthma which produces pharmacologic effects similar to caffeine and found that overall the stimulant produced no negative cognitive or behavioral outcomes.

In fact, the drug seemed to produce "a mild positive effect on externalizing behavior," he says, in addition to "less aggression and more compliance."

Stein thus extrapolated that mild to moderate doses of caffeine could actually improve children's behavior--but not without a caveat. The studies "only measure behavior without looking at long-term effects," he admits. "I would thus not encourage children to take more caffeine, but I also don't think mild amounts are a major problem."

Stein gages moderate consumption at "one to two cups of coffee," he says, "but an important point to make is there are huge individual differences in reaction to caffeine. And with the advent of Starbucks, it is easier to get higher caffeine doses which taste good to teen-agers," Stein adds. "The consequences of escalating caffeine use have to be studied; I wouldn't give it a clean bill of health just yet."