Although energy drinks in moderation can enhance an individual’s response time, the benefits disappear once consumption becomes a regular habit, according to a study published by the American Psychological Association.
“Several aspects of cognitive performance that show improvement under the influence of caffeine are attention, reaction time, visual search, psychomotor speed, memory, vigilance and verbal reasoning,” said co-author Cecile A. Marczinski, Ph.D., of Northern Kentucky University.
Monster, Red Bull, and Rockstar are becoming increasingly popular among high school and college students, and psychologists are keen to explore how these sugar-laden, highly caffeinated drinks affect young people.
In particular, college students consume energy drinks to stay awake, focus on study materials and reduce the effects of alcohol. However, using energy drinks to slow alcohol intoxication has recently landed many young people in hospital emergency rooms. This has led some state liquor control boards ban the drink Four Loko, a combination of caffeine and alcohol.
“The results of the current study illustrate that energy drinks can increase stimulation and decrease mental fatigue, suggesting that they may be used with alcohol to counteract the sedation associated with drinking,” said Marczinski.
For the study, researchers recruited 80 college students (34 men and 46 women) between the ages of 18 and 40. The first group was given Red Bull 7; a second group was given lower amounts of caffeine added to Squirt, a decaffeinated soda that looks and tastes like Red Bull; a third group was given a placebo—plain Squirt with no additional caffeine.
Half an hour after the participants finished their drinks, they were asked to play a computerized “go/no-go” test in which they had to respond quickly to targets on a screen. When a green target appeared, they needed to hit the forward slash key, and when a blue target appeared, they were supposed to do nothing.
Researchers also asked the volunteers how stimulated and mentally fatigued they felt after consuming their drinks. The students who drank Red Bull said they felt more stimulated and less tired than the other participants, but their response rates were actually slower.
“This finding is of interest given that energy drinks are frequently mixed with alcohol and the acute effects of alcohol impair response inhibition,” Marczinski said.
“Since regulation of energy drinks is lax in the United States in regard to content labeling and possible health warnings, especially mixed with alcohol, having a better understanding of the acute subjective and objective effects of these beverages is warranted.”
In another study reported in the same journal, Jennifer L. Temple, Ph.D., and colleagues at the University at Buffalo found boys and girls had different physiological responses to caffeine. For this research, 26 boys and 26 girls between the ages of 12 and 17 drank flat Sprite with added caffeine in three concentrations: 50 mg, 100 mg or 200 mg. Flat Sprite with no caffeine was included as a placebo.
Every 10 minutes for one hour, the volunteers were tested for any changes in blood pressure and heart rate. Once the hour was over, the students were given a questionnaire and the opportunity to eat as much as they wanted of the following junk foods: Skittles and Smarties (high sugar, low fat); potato chips and Doritos (low sugar, high fat); and M&Ms and Twix (high sugar, high fat).
Boys who had consumed high amounts of caffeine had greater increases in their diastolic blood pressure than boys who ingested less caffeine. In girls, however, there was no association between blood pressure and caffeine intake. Furthermore, those students who had the most caffeine chose more high-sugar snack foods in the laboratory compared to low-caffeine consumers.
The researchers also found that boys and girls had different reasons for drinking caffeine. Boys were more likely than girls to report drinking caffeine “to get energy,””‘to get a rush” and for “athletic performance.”
“Adolescents are among the fastest growing consumers of caffeine and yet very few empirical studies have focused on this population,” Temple said.
“It is imperative that we understand the impact of caffeine use on adolescents.”
The research can be found in the December issue of the APA journal Experimental and Clinical Psychopharmacology.