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Does Caffeine have an effect on the Human Process of Memory?

Mariana Gonzalez

January 29, 2009

 

On college campuses (Vanderbilt included) many students pull all nighters on days before tests in order to study, and use the aid of such products such as Red Bull and Coffee to enable them to stay up and study. Does the consumption of these chemicals help us retain information? It seems like an appropriate question to ask due to the fact that many individuals drink these products in order to pay attention in class. Is their consumption directly related to memory or more so attention which in return helps students transfer more information into their memory?

Summary

The intention of this review is to evaluate the affect that caffeine has on human memory. To conduct my research I searched online databases for experiments and reviews already made about the topic. After two weeks of ongoing research, I had narrowed down my resources to eight from about twenty. Most of the experiments concluded that there was no significant increase in memory gain from caffeine, but there was a positive correlation. Many professionals attributed this to the effects caffeine has on the body (which were already known) and therefore attribute the positive correlation with other reasons such as enhanced participation. Although most of the research I found was inconclusive, there were some academic articles that cited and used ongoing research that has attributed caffeine usage with stimulation of certain parts of the brain that do in fact directly correspond to memory.

Introduction

Caffeine

:::Desktop:Caffeine.jpgCaffeine is a naturally occurring stimulant in the leaves, seeds, or fruit of over 60 plants around the world. It is also the most widely used psychoactive, or mind altering, substance in the world. Its affect on humans socially and behaviorally include elevated mood, decreased fatigue, increased attentiveness, and a person can think more clearly and harder. Biologically, Caffeine increases heart rate, blood flow, respiratory rate, and metabolic rate. Studies have proven that Caffeine is mildly addictive and tolerance to the amounts of caffeine ingested and its effects may develop. Most experts say that moderate use of caffeine is not likely to cause any health problems, but large quantities, such as in most energy drinks, tend to give the consumer insomnia, nervousness, headache, and tachycardia (excessively rapid heart rate). There have been four documented deaths from Caffeine, and four other cases of seizures due to caffeine in energy drinks.

Memory

In basic terms, memory is the ability to store and retrieve information over time. The three main steps in memory are encoding (processes associated with receiving or registering stimuli through one or more of the senses and modifying that information), storage (which can also be split into categories such as short term and long term), and lastly retrieval (which is the process in which we recall the information which has been successfully stored into our memory). A very important distinction can be made according to the type of storage used. Short-term memory is a place where nonsensory information is kept for more than a few seconds but less than a minute and long-term memory is a place in which information can be kept for hours, weeks, months, and years. The area in the brain called the hippocampus has been proven to show increased activity when remembering things from memory in innumerable experiments.

 

Research

Research was conducted over the topic from the dates January 15th to January 25th by the use of online databases. The following databases were used: PubMed, WebMD, SpringerLink, and Google Scholar. The search terms used were: Caffeine, short-term memory, and long-term memory (and variation of the three terms paired together). Studies and Essays were excluded from the original twenty found if the subjects being tested were animals, the experiment conducted had to do with physical activity (Caffeine is often associated with ongoing physical activity), and if the experiment was not relevant to the subject. The most commonly found research materials were short online briefs about past experiments held on the topic.

Results

Articles

In sticking with popular belief I also encountered some news articles that claimed that Caffeine had a positive impact on memory.

In an article found on Web MD, a practical and trusted resource, author Miranda Hitti claims that Caffeine boosts short-term memory. In a study with a dozen adults, caffeine boosted activity in brain regions related to attention and short-term memory. The participants ingested 100 mg of Caffeine, which is roughly the amount in one cup of coffee. They were tested twice. In one trial Caffeine was actually consumed, and in the other Caffeine was replaced by a placebo. Their brains were scanned using the MRI technique while taking verbal memory tests and the researchers claim that this is the first time that it has been scientifically proven that caffeine has this effect directly tied to the regions of the brain that are important in short term memory and attention. (http://www.webmd.com/brain/news/ 20051130/caffeine-boosts shortterm-memory)

In another article, less trusted, printed by a website by the name Energy Fiend, the author (unknown) claims again that by drinking a lot of caffeine one can get a memory boost. This resource is not very reliable because it is bias towards gaining energy in the form of caffeine and other methods. The website from where it was pulled contains many advertisements for energy drinks, and energy pills. But according to the article that was written from information found in the Mainichi Daily News, brain cells in the hippocampus are stimulated to increase calcium concentration when caffeine is consumed. This in turn improves the cells signal flow and this in turn improves memory. (http://www.energyfiend.com/2008/08/boost-memory-drink-lots-of-caffeine)

 

Experiments

In an experiment conducted by Feierabend JM (1984) 48 subjects were tested by polygraphic monitoring of several variables that were done throughout the experiment investigating the effects of caffeine on mental performance. The experiment was set up with 4 groups of individuals. One group was served regular coffee, another was served decaffeinated coffee, another warm water, and the last was not served a beverage. After ingesting the beverage subjects were asked to engage in tasks such as mental maze learning task, letter cancellation task, and a second mental maze. The experiment concluded that at the dosage of caffeine ingested (300 mg) the drug improves behavioral routine and speed rather than cognitive functions.

Two experiments conducted by Warburton DM (1984) tested the effects of caffeine on physiological functions and mental performance. A total of forty-two participants were tested with a rapid visual information test, a verbal reasoning test, a verbal and non-verbal memory test, and a set of mood measures. The first study tested participants after they were allowed a set amount of caffeinated beverages an hour before testing. In the second study the participants were allowed to consume an unlimited amount of caffeine before being tested. The conclusions in both studies results showed that the caffeine produced improved attention and verbal reasoning compared to the control group who had consumed sugar free and sugar containing drinks. With all this said, Warburton still concluded that no direct effects on memory were found.

In another experiment held by Mitchell PJ (1992) a group of 25 subjects that was composed of six males and nineteen females was interviewed about their past consumption of caffeine. The subjects were then tested on short-term memory, mental arithmetic, reading comprehension, serial search, and verbal reasoning at four different times a day after ingesting 4 mg/kg of caffeine. All subjects were categorized in a low, moderate, or high user group based on the interview beforehand and the amount of caffeine that had been consumed in the months prior to the experiment. The results were, that reading comprehension was correlated with the time of day, and caffeine was seen to improve all other mental speed related tasks.

A more specific experiment was held by the Psychology Department at the University of North Dakota (1984) by six professionals that chose to experiment the effects of caffeine on memory for word lists in men and women. The study consisted of one hundred and seven university students (47 of which were male and 60 of which were female) and separated them into twelve groups. Four of the twelve groups received no caffeine, two groups ingested 2 mg/kg of caffeine, and the remaining four groups ingested 4 mg/kg of caffeine before the experiment was conducted. The groups were then divided into high and low impulsivity and then further divided by sex. There were two trials done of the experiment. The first trial was held with a slow word list (one word every three seconds) and another trial was held with a fast word list (one word every second). There were eight tested word lists that consisted of twelve words each. Each word was on average comprised of one to three syllables. The primary result for the study was that caffeine impaired recall for females but not for males. The conductors of this study suggest that caffeine may be affecting the efficiency with which the information was encoded or manipulated in working memory. The study does point out that the difference between men and women may be the average consumption of caffeine-consumed daily by both sexes, creating some tolerance in female participants. Prior interviews conducted showed that women (for the most part) consumed more caffeine daily than men. In conclusion this study offered no direct answer to the question at hand, but they did suggest that further research should be conducted in order to pin point the difference between caffeine consumption in males and females and why it happened to affect females working memory and not males.

The last study researched was conducted by the department of Psychiatry and Neuropsychology at Maastricht University (1998) by 4 experimenters. This study was also more specific than the others presented in this analysis much like the study conduced at the University of North Dakota. They focused on the effects of caffeine on memory in correlation with age. The experimental design was as follows. Sixty participants were separated into three age categories. The first group, the young group, consisted of people between the age of 26 and 34, the second group, or the middle aged, consisted of participants from 46 to 54 years of age and the last group, or the old group consisted of subjects from the age of 66 to 74. All groups had twenty pre-selected individuals that were seen to be healthy. The participants drank 225 mg of caffeine in a total of three cups of coffee while the control group drank 225mg worth of decaffeinated coffee. They were then tested with a memory activity. In sum, age related changes in information processing might underlie the effects of caffeine on cognitive performance. Caffeine turned out to have a negative effect on the younger group when recalling short-term memory, but the middle aged group greatly benefitted from this. The middle-aged group that got the placebo had very low memory scores. Scientists believe that this discrepancy is because of the regular consumption of caffeine by middle-aged persons. This dependency plummets when it is replaced with a placebo. Therefore caffeine withdrawal has a larger effect on memory than caffeine consumption.

Conclusions

From the experiments up to date, the data is inconclusive. Some studies believe that it helps increase memory storage and others say it helps other things such as attention, which in turn helps memory. The basic agreement between experimenters is that there is a correlation between memory and caffeine but not causation between the two variables. Future and ongoing experiments seem to have documented that caffeine does increase memory retention and that certain parts of the brain such as the hippocampus that specialize in memory and attention are activated with the consumption of caffeine. After analyzing all of the experimental reviews and articles (not including the recent unpublished experiments talked about in the news articles) I have come to the conclusion that caffeine does not directly cause an increase in short term memory, but does improve behavioral aspects such as attention that help increase memory due to a better ability to encode information into storage. By this process it is easy to se why the media and popular belief state that drinks such as Red Bull and coffee not only help you stay up longer, but also might actually help retain more information. In short the caffeine is not what is retaining more information in the brain it is the effect of the caffeine (greater attention) that helps improve retention of information.

 

 

Literature Cited

Boost Memory: Drink Lots of Caffeine. (2008, August 6). Energy Fiend. Retrieved January 21, 2009, from Google database.

 

Caffeine. (n.d.). Nutrition and Well Being A to Z [Fact Sheet about Caffeine]. Retrieved January 22, 2009, from Encyclopedia.com database: http://www.encyclopedia.com

 

Erikson, G. C., Hagar, L. B., Houseworth, C., Dungan, J., Petros, T., & Buckwith, B. E. (1984, September). [Review of the experiment The Effects of Caffeine on Memory for Word Lists]. Physiology & Behavior, 35, 47-51.

 

Feierabend JM. (1984, November 15). The effects of caffeine on physiological and mental performances [abstract]. Retrieved January 21, 2009, from PubMed database.

 

Hitti, M. (2005, November 30). Caffeine Boosts Short-Term Memory. WebMD. Retrieved January 22, 2009, from WebMD database: http://www.webmd.com/brain/news/ 20051130/caffeine-boosts shortterm-memory

 

Hogervorst, E., Riedel, W. J., Schmitt, A. J., & Jolles, J. (1998). [Review of the experiment Caffeine Improves Memory Performance During Distraction in Middle Aged, But Not in Young or Old Subjects]. Human Psychopharmacology, 13, 277-284.

 

Mitchell P.J. (1992). Effects of caffeine, time of day and user history on study related performance [Abstract]. Retrieved January 21, 2009, from PubMed database.

 

 

 

 

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