Mar 18, 2011 by Bill Jenkins, Ph.D.

Effects of caffeine on the brain

Whatever your personal opinion of that daily coffee or diet soda might be, we as a society—not just as individuals, but as a whole society—have made the use of caffeine into a daily ritual. For some it is an approved indulgence. For others, it represents an absolute need.

While this is obviously a problem amongst adults, it represents adverse example-setting when practiced in the presence of children. Every time we pull through the drive-thru for that daily double-mocha, every time our children hear us say, “I need a diet soda,” we send a message to our charges in the back seat that this is a necessary part of our daily, adult lives.

That stage is being set, so let’s take a step back and look objectively at this habit of caffeine, both in ourselves and our children.

Make no mistake: caffeine is a drug. As a psychoactive compound, this stimulant blocks the action of adenosine and adenosine receptors. Essentially, caffeine binds to adenosine receptors in nerve cells, but it doesn’t slow down the cell’s activity; instead, it speeds it up. Also, while adenosine opens blood vessels, caffeine causes them to constrict.

On the “positive” side, the immediate effects in humans range from enhanced cognitive performance (Smit and Rogers, 2000) to auditory vigilance (Lieberman et al., 1987) to improved reaction time (Durlach, 1998; Lieberman et al., 1987). [i]

But on the “negative” end of the spectrum, it causes high blood pressure, increases heart rate, disrupts sleep cycles, and negatively impacts attention spans.

As the body becomes habituated to the drug, it compensates for these effects, and begins to require more caffeine to function at normal levels. One study showed that children aged 9-10 who regularly drank two or fewer cans of cola a day were less alert than their non-indulging counterparts. [ii]In short, the more caffeine we take in, the less of its effects we experience, and the less we are able to function at normal levels of alertness.

Aside from the stimulant nature of caffeine, we cannot ignore how it is delivered: children and adolescents primarily get caffeine doses through drinking soda and energy drinks. During their most formative years, they are repeatedly exposed to and conditioned to the paring of sugar and caffeine. Interestingly, Robinson and Berridge refer to sugar as a “natural reward” that “activates similar reward pathways as drugs of abuse, such as cocaine, amphetamine, and nicotine.” [iii]

So along with decreased brain function, these habits can potentially contribute to life-long afflictions like diabetes and obesity.

Lastly, let’s add to this the fact that childhood and adolescence is the fastest stage of brain development. At this time, proper sleep and nutrition are critical elements in laying the foundation for future brain health and fitness. The consumption of caffeine and sugar undermines both.

We know the habits that contribute to a healthy life. Maintaining good nutrition, getting the right amount of sleep and staying away from drugs are all key lessons that we want our younger generations to internalize. How can we help make that happen?

As challenging as it might be, might we consider starting with ourselves, ditching the daily double-mocha and diet soda, and taking the first step toward leading by example? By becoming more aware of our own habits, maybe we can begin to help our children take positive control of their own.


[i]Temple, Jennifer L. (2010) Caffeine Use in Children: What we know, what we have left to learn, and why we should worry. Neuroscience and Biobehavioral Reviews. 2009 June; 33(6): 793–806.

[ii]Heartherley, S.V., Hancock, K.M.F. and Rogers, P.J. (2006) Psychostimulant and other effects of caffeine in 9-11-year-old children. Journal of Child Psychology and Psychiatry. 47-2, 135-142.

[iii]Robinson TE, Berridge KC . The psychology and neurobiology of addiction: an incentive-sensitization view.

Addiction. 2000 Aug;95 Suppl 2:S91-117.

Related Reading:

What Every Parent Should Know about Their Baby’s Developing Brain (Part 2)

Adolescence: What’s the Brain Got to Do with It?