Please welcome this month's Scicurious Guest Writer: Elizabeth Aston!

We all enjoy going out for a few drinks, but sometimes, just when the party’s getting started, we feel like passing out! Wouldn’t it be great if we could keep our energy level up so the party could continue? Initially this may seem like a great idea, but in reality, drinkers who try to skip the alcohol-related sleepiness often get a lot more than they bargained for.

Many drinkers have been buying in to the new fad of mixing alcohol with caffeine, especially caffeinated alcohol-energy drinks such as the formerly caffeinated Four Loko*, or by mixing vodka and Red Bull. Many of these alcohol-energy beverages are pre-mixed, easily attainable, brightly colored, taste like liquid candy, and boast 12% alcohol by volume per can - this is essentially an entire bottle of wine in one handy binge-can. The original Four Loko formula included alcohol (equivalent to about 4.5 beers), caffeine (approximately 156 mg or about two cups of coffee), guarana, and taurine (two other herbal stimulants in unspecified amounts). This alcohol-energy drink craze has prompted development of an entire website devoted to Four Loko anecdotes delving into the crazy and often terrifying experiences of drinkers under its influence. Getting drunk and partying all night? Yes please! Or…maybe not.

At first as you drink, you probably recall feeling very interesting, “buzzed”, talkative, and charming. Many drinkers develop very “impressive” dance skills and carry on conversations with a variety of inanimate objects. After the initial stimulation dissipates, drinkers begin to feel very tired, fatigued, sedated (Morean & Corbin, 2010), and may ultimately throw up on a stranger, shower with their clothes on, or pass out in the middle of eating Taco Bell. Many drinkers hate the sedating effects of alcohol, but actually, sedation is one way of telling you when you’ve had enough alcohol for the evening (King, de Wit, McNamara, & Cao, 2011). In fact, increased sedation after drinking alcohol may even make you more cautious because you know you are too tired to drive. (Marczinski, Harrison, & Fillmore, 2008).

Alcohol may be more sedating in the end, but caffeine is a more…stimulating subject. Coffee and other caffeinated drinks are part of the morning/afternoon/late night routine for many people including workaholics, graduate students, new parents, and procrastinators. Avid caffeine consumers swear by its ability to help them stay awake to work, study, and play longer. Even so, drinking too much caffeine isn’t so fun, and can lead to irritability, tremors, insomnia, nausea, and heart palpitations.

Consuming alcohol results in one set of effects, and consuming caffeine results in a completely different set of effects. When used in moderation, both alcohol and caffeine consumed alone can have positive outcomes. Despite this, most of us have experienced very negative consequences from consuming too much of either beverage. What about alcohol and caffeine together? When alcohol and caffeine are combined, the effects and ultimate results become much more complicated.

Alcohol drinkers who also consume caffeine feel awake, talkative, and stimulated for a much longer period of time compared to when they drink alcohol alone. However, the added caffeine does not make you less drunk or less likely to go home with a grenade. Furthermore, the sedation that always accompanies drinking alcohol is often muted, or experienced much later when caffeine is in the picture.

Dr. Cecile Marczinski of Northern Kentucky University conducted a recent study further investigating the difference between consuming alcohol alone and co-ingestion of alcohol and caffeine (Marczinski, Fillmore, Henges, Ramsey, & Young, 2012). Fifty-six college-aged social drinkers (over 21) were recruited to participate in the study. In this case, college students are the perfect demographic because they are the ones lining up on Friday nights at fine gas stations across the country for these drinks. The researchers were interested in looking at differences in impulsivity (what makes you decide to go skydiving at the last minute) and disinhibition (what makes you feel comfortable removing articles of clothing in public) between subjects who drank each of the four beverages. To look at disinhibition and reaction time, the researchers used something called a cued go/no-go task. The cued go/no-go task measures the ability to initiate an action and the ability to stop or inhibit an action. Essentially this task measures how fast you can press a button, and whether you can stop yourself from pressing the button once you have started. Participants are instructed to press a key on a computer keyboard as quickly as they can whenever a “go target” appears, in this case a green target. At the same time, participants are asked not to press a key whenever a “no-go target” appears, in this case a blue target.

The targets appear very quickly, and the speed with which a subject reacts to each “go target” (fewest milliseconds) while still maintaining accuracy (inhibiting responses to “no-go targets”) is analyzed. A sober person can usually respond to a “go target” in about 290 milliseconds (less than one third of a second), while a drunk person usually takes at least 300 milliseconds to respond to the same target. This may seem like a very small amount, but it is the difference between hitting the brakes in time…or not.

At the beginning of the study, the authors collected information from the subjects, including personal drinking habits, daily alcohol consumption over the past month, caffeine consumption, impulsivity, and attention. Subjects then tried a baseline trial on the cued go/no-go task, and answered questions about their current, personal level of energy and sedation (things like “I feel stimulated” or “I feel down”). Then, the drinkers were given one of four beverages that they were told to consume steadily over ten minutes: an energy drink (Red Bull), an alcohol drink (Smirnoff Red Label vodka, science budgets are tight these days), an alcohol-energy drink beverage (Red Bull and Smirnoff Red Label vodka) or a placebo beverage (carbonated, lemon-flavored decaffeinated soda [Squirt]). Squirt was used for the placebo condition because it is similar in taste, carbonation, and appearance to Red Bull (and presumably, the subjects didn’t notice any difference). A small amount of the vodka was floated on the top of the placebo beverage to fool any suspicious participants about the alcohol contents. The alcohol dose used in both the alcohol and alcohol-energy drink conditions was 0.65 g/kg which is equivalent to a little more than three beers or three regular mixed drinks. Forty-five minutes after finishing the beverage, subjects completed the cued go/no-go task once more, and provided ratings of stimulation and sedation a second time.

Subjects who got Red Bull, Red Bull and vodka, or Squirt had no trouble with the “go” – they responded more quickly to the “go targets” after the drinks. Subjects who drank vodka alone responded to the “go targets” more slowly than they had before the drinks, because reaction time is usually impaired by alcohol. The differences came up in the “no go” condition. Subjects who got Red Bull and vodka together had more trouble stopping or inhibiting themselves from responding to “no-go targets” compared to subjects in the non-alcohol conditions.

What about how they felt? The subjects drinking vodka and Red Bull together reported the greatest increase in how stimulated and energetic they felt following the beverage compared to baseline – even greater than the subjects who drank Red Bull Alone! Despite this, the energy drink did not change the effect of alcohol on the other subjective measures including how drunk or tired the subjects felt or how well they thought they could drive. This is good news! In this particular study, the subjects who received vodka and the subjects who received Red Bull and vodka both felt that their driving ability was impaired. However, several other recent studies have actually shown that drinkers who consume alcohol mixed with caffeine or an energy drink are more likely to drive after drinking these beverages (e.g., O’Brien, McCoy, Rhodes, Wagoner, & Wolfson, 2008; Thombs et al., 2010).

Increasing how stimulated and energetic a drinker feels can be very dangerous when it is combined with a decreased ability to inhibit actions due to alcohol. These individuals have elevated confidence and energy levels, slowed reaction time, and are less able to stop themselves from drinking – probably not a formula for success! Not to mention the other dangers these alcohol-energy drinks pose to drinkers, including increased likelihood of riding with a drunk driver, getting hurt, or needing medical attention (O’Brien et al., 2008). In 2010, the United States Food and Drug Administration (FDA) came down hard on Phusion Projects, LLC (developers of Four Loko) and other alcohol-energy drink manufacturers. The FDA informed several alcohol-energy drink companies that they would need to alter the ingredients of their beverages or products would be seized due to potentially hazardous safety issues (United States Food and Drug Administration, 2010). However, the demands imposed by the FDA have not prevented bars, gas stations, and 7-Elevens across the country from continuing to sell and promote the alcohol-energy drink combination. When a drinker is less able to evaluate how drunk they are, they are three times more likely to reach the legal limit, and four times more likely to drive home after drinking than drinkers who consume non-caffeinated beverages (Thombs et al., 2010). Just because your energy level is high doesn’t mean you are less impaired. Ignoring that fact would be loko.


King, A. C., de Wit, H., McNamara, P. J., & Cao, D. (2011). Rewarding, stimulant, and sedative alcohol responses and relationship to future binge drinking. Archives of General Psychiatry, 68(4), 389–399. doi:10.1001/archgenpsychiatry.2011.26

Marczinski, C. A., Fillmore, M. T., Henges, A. L., Ramsey, M. A., & Young, C. R. (2012). Effects of energy drinks mixed with alcohol on information processing, motor coordination and subjective reports of intoxication. Experimental and clinical psychopharmacology, 20(2), 129–138. doi:10.1037/a0026136

Marczinski, C. A., Harrison, E. L. R., & Fillmore, M. T. (2008). Effects of alcohol on simulated driving and perceived driving impairment in binge drinkers. Alcoholism: Clinical and Experimental Research, 32(7), 1329–1337. doi:10.1111/j.1530-0277.2008.00701.x

Morean, M. E., & Corbin, W. R. (2010). Subjective response to alcohol: a critical review of the literature. Alcoholism: Clinical and Experimental Research, 34(3), 385–395. doi:10.1111/j.1530-0277.2009.01103.x

National Institute of Alcohol Abuse and Alcoholism. (2004). NIAAA council approves definition of binge drinking (Vol. 3).

O’Brien, M. C., McCoy, T. P., Rhodes, S. D., Wagoner, A., & Wolfson, M. (2008). Caffeinated cocktails: energy drink consumption, high-risk drinking, and alcohol-related consequences among college students. Academic emergency medicine: official journal of the Society for Academic Emergency Medicine, 15(5), 453–460. doi:10.1111/j.1553-2712.2008.00085.x

Thombs, D. L., O’Mara, R. J., Tsukamoto, M., Rossheim, M. E., Weiler, R. M., Merves, M. L., & Goldberger, B. A. (2010). Event-level analyses of energy drink consumption and alcohol intoxication in bar patrons. Addictive behaviors, 35(4), 325–330. doi:10.1016/j.addbeh.2009.11.004

United States Food and Drug Administration. (2010, November 17). FDA warning letters issued to four makers of caffeinated alcoholic beverages. Retrieved from PressAnnouncements/ucm234109.htm

Dr. Elizabeth Aston is a postdoctoral researcher in the laboratory of Dr. Anthony Liguori. She received her Ph.D. in Neuroscience from Wake Forest School of Medicine, and studies responses to alcohol in binge drinkers. She hopes to continue studying problematic alcohol consumption and drug abuse. Dr. Aston sampled Four Loko only once, and now enjoys both caffeine and alcohol, but definitely not together.

*Clarification (7:14 PM EST, 2/27/13): Phusion Projects removed the caffeine, guarana, and taurine from their alcoholic beverage Four Loko, and the new, non-caffeinated product has been sold since November, 2010. The current Four Loko product contains only alcohol, not caffeine.