Caffeine is hardly a new addition to the human diet. There is evidence of caffeine consumption in all societies since the Stone Age. According to popular opinion, caffeine can make up for lack of sleep and improve alertness and mood. Newer studies, however, show there is more evidence for caffeine improving short-term memory than for directly affecting alertness.
Short-Term Memory
There are two kinds of short-term memory: working memory and short-term storage memory. Working memory is the ability to keep information active and in immediate reach for a short period of time. Short-term storage memory is the ability to store information for up to a few days. The two kinds of memory have different neural correlates. Working memory is primarily a function of activity in the frontal areas of the brain, whereas short-term storage memory correlates with the formation of neural networks in the hippocampus, the brain's main memory center.
Caffeine and Alertness
Caffeine, a white crystalline xanthine alkaloid, is a legal central nervous system stimulant found in a variety of beverages, including coffee, tea, cola and energy drinks. Caffeine is said to temporarily ward off drowsiness and improve alertness. Recent studies, however, counter this common belief. A research team led by Peter Rogers of the University of Bristol tested the effect of caffeine or a placebo on 379 participants who had not had caffeine for 16 hours. The team found no significant improvement in alertness in participants who received the caffeine compared to the controls.
Positive Effects on Short-Term Memory
Despite the failure to show any correlation between alertness and caffeine in regular coffee drinkers, caffeine has been found to enhance both working memory and short-term storage memory. A study published in the August 2007 issue of "Neurology" showed that elderly women who drank three cups of coffee or more a day had less decline in both working and storage memory compared to controls. A more recent, study published in the July 2009 issue of "Journal of Alzheimer's Disease," showed that caffeine can reverse the symptoms of Alzheimer's disease in aging mice. The researchers found that when the mice were given caffeine that corresponded to about five cups of coffee a day, the initial signs of cognitive impairment were reversed.
Adverse Effects in Children
According to a study published in the December 2010 issue of "The Journal of Pediatrics," caffeine can have adverse effects on attention and memory in children. In children, caffeine negatively affects the length and quality of sleep. The higher the caffeine intake, the less the child sleeps. Poor sleep habits lead to severe difficulties concentrating and storing information. In children, the cognitive impairments caused by excessive caffeine intake thus outweigh the positive effects of caffeine on memory.
References
- Carnegie Mellon University, School of Computer Science; Working Memory versus Short Term Memory; David Crow
- ScienceDaily: Coffee Consumption Unrelated to Alertness: Stimulating Effects May Be Illusion, Study Finds
- ScienceDaily: In Women, Caffeine May Protect Memory
- PhysOrg.com: Caffeine Reverses Memory Impairment in Alzheimer's Mice
- "The Journal of Pediatrics"; Caffeine Consumption in Young Children; William J Warzak, et al.; December 2010
