Written by Sarya Güleç
Coffee, cola, and energy drink… Caffeine is the most used stimulant with some research stating that two billion cups of coffee are consumed every day worldwide. No doubt, caffeine makes most of us feel more alert. It belongs to the group of compounds that have a stimulant effect on the central nervous system (4). There have been researches about how this stimulant influences both humans and animals. The majority of the studies reviewed, suggest caffeine as having a positive effect on both short and long-term memory in both adults and the elderly.
A study has tested the effect of caffeine on rats’ memory, using a water maze task. The rats in this study were either given caffeine immediately after training, 30 minutes before training, or 30 minutes before they were to be tested in the maze. The study concluded that caffeine consumption was linked to greater memory retention in rats; however, the consumption was not related to memory acquisition (2).
Image Credit: https://universityhealthnews.com/daily/memory/how-does-caffeine-affect-the-brain-and-the-brains-grey-matter/.
In the brain, adenosine and adenosine receptors regulate the release of neurotransmitters and play an important role in the regulation of sleep, arousal, cognition, memory, and learning (2). Adenosine connects with adenosine receptors, when caffeine binds to adenosine receptors which in turn blocks the binding of adenosine to its receptor. The blockage of adenosine receptors indirectly affects the release of neurotransmitters such as norepinephrine, dopamine, acetylcholine, serotonin, glutamate, and gamma-aminobutyric acid (GABA). An influx in these neurotransmitters alters mood, memory, alertness, and cognitive function (2).
A group of 20 healthy young individuals, all of whom regularly drink coffee on a daily basis, took part in the study. They were given tablets to take over two 10-day periods and were asked not to consume any other caffeine during this time. During one study, they received tablets with caffeine; in the other, tablets with no active ingredient (placebo). At the end of each 10-day period, the researchers examined the volume of the subjects' gray matter by means of brain scans. They also investigated the participants' sleep quality in the sleep laboratory by recording the electrical activity of the brain (EEG). The results showed that the quality of sleep was not affected but the gray matter was. The researchers observed changes in the gray matter, as they reported in the journal Cerebral Cortex. Gray matter refers to the parts of the central nervous system made up primarily of the cell bodies of nerve cells, while white matter mainly comprises the neural pathways, the long extensions of the nerve cells. The volume of gray matter cells was greater with the users.
It has been confirmed in other research that their sleep quality decreases if they drink coffee or other caffeine beverages close to bedtime. Also, it is known that sleep deprivation can in turn affect the gray matter of the brain. However, this study suggests that sleep is not necessarily influenced by regular use. Although the grey matter is reduced by caffeine the change in the brain is only temporary.
Image Credit: https://www.theguardian.com/news/2013/nov/27/caffeine-compared-coke-coffee-aspirin-chocolate-tea.
Another study about the effect on rats showed that higher doses of caffeine before training impairs memory retention, caffeine improves memory consolidation but at low doses. This improvement cannot be generalized for all types of behavior, caffeine at moderate doses improves memory retrieval before the test.
High doses can lead to neurotoxicity. Neurotoxicity has been observed in cerebellar granular cells isolated from rat pups. This study found that the effect was abolished following pre-treatment (45 min prior to the caffeine treatment) with nimodipine, a calcium channel blocker. The study concluded that newborn apneas due to neurotoxicity, which is induced by high doses of caffeine, could be prevented by nimodipine(5). Another study showed that, at the dose of 50mg/kg 3 times a day, induced marked neuronal death in different brain regions in neonatal rats.
References:
University of Basel. (2021, February 16). Regular caffeine consumption affects brain structure. ScienceDaily. Retrieved October 27, 2023 from www.sciencedaily.com/releases/2021/02/210216100137.htm
Fiani, B., Zhu, L., Musch, B. L., Briceno, S., Andel, R., Sadeq, N., & Ansari, A. Z. (2021, May 14). The neurophysiology of caffeine as a central nervous system stimulant and the resultant effects on cognitive function. PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8202818/
Windell, J. (2021, February 21). Drinking caffeine regularly will change your brain. Home. https://www.michiganpsychologicalassociation.org/index.php?option=com_dailyplanetblog&view=entry&year=2021&month=02&day=21&id=70:drinking-caffeine-regularly-will-change-your-brain
Munawar, A. (2021, December). DIFFERENTIAL EFFECT OF CAFFEINE ON MEMORY AND LEARNING. ResearchGate. https://www.researchgate.net/publication/359507131_DIFFERENTIAL_EFFECT_OF_CAFFEINE_ON_MEMORY_AND_LEARNING
Alasamari, F. (2020, April 4). Caffeine induces neurobehavioral effects through modulating neurotransmitters. sciencedirect. https://www.sciencedirect.com/science/article/pii/S1319016420300359
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