The Biomedical Features of Caffeine

The Need for Caffeine

Jacob Sorenson

Mike Thomas

Biology 181 Honors Paper

December 4, 2014

        Caffeine is a substance so commonly used in our lives, yet most of us do not truly know what it is or how it works. This is a substance that is extremely abundant and never more than a cup of joe or monster energy drink away. But what are we really doing to our bodies when we ingest this substance? Is it harmful? Will it affect us positively? Many studies have been going on for years on this simple compound and the research is quite revealing. The effects of caffeine have been proven to be effective and positive in many ways and new research is developing ways to use caffeine.

        What is caffeine? It is simple to say it is made from coffee beans, tea leaves, and other sources, but what truly is caffeine? Caffeine is made up of this compound structure, C8H10N4O2. It is a bitter, white crystalline xanthine alkaloid and a stimulant drug. Caffeine is a stimulant that is classed as a psychoactive drug. This substance is an adenosine antagonist which means it blocks all adenosine receptors from receiving adenosine in the nervous system. Each adenosine receptor plays a different role in the central nervous system and caffeine’s ability to block all receptors is huge. When adenosine binds to each receptor it causes certain affects such as slowing down our neural activity and sleepiness. Caffeine has the effect of binding to these same adenosine receptors and taking the place of adenosine, thereby stopping the sleepiness effect. This then produces adrenaline which helps to pick up our senses and gives us that boost of energy we feel. Also, caffeine produces dopamine in our brains. This plays a huge part in why consumers of caffeine continue to want more, it’s that “feel good” feeling (Mandal).

        What exactly are these adenosine receptors and why do they effect the body in the way they do? In the body, adenosine helps in cellular energy transfer by forming molecules like adenosine triphosphate and adenosine diphosphate. Adenosine is a normal cellular constituent that is regulated mainly by ATP metabolism and other adenine nucleotides. Adenosine concentrations increase in muscle and plasma during muscular contraction.   In the brain adenosine is an inhibitory neurotransmitter. This means, adenosine can act as a central nervous system depressant. In normal conditions, it promotes sleep and suppresses arousal. Adenosine concentrations also increase progressively in the brain during wakefulness and then decrease during sleep. Adenosine inhibits the release of most brain excitatory neurotransmitters, especially dopamine (Ribeiro).  This is why caffeine plays such a huge role in effecting our body. It is able to break up the natural process of adenosine and give us the energy we need when we want it.

        Caffeine is such a functional substance that it has many positive effects. Caffeine has had many tests done that show it is a positive cognitive enhancer. It has been proven that it can increase memory gain. In a study done by Johns Hopkins University, it has been concluded that dosing a person with 200mg of caffeine directly after a learning process will have a positive effect in the memory consolidation of that person. The test included a group of twelve random people who did not consume caffeine on a daily basis. Each person was given a view of a series of pictures of everyday objects that were used either indoor or outdoor. Objects such as a basketball for outdoor and a wine glass for indoor. Immediately following the training, they were given one of either a placebo, 100mg, 200mg, or 300mg tablet of caffeine. The next day the participants came into the same facility to participate again. The first thing that was done was salivary samples to make sure the caffeine from the day before was out of their system, which it was. Only this time the participants were given a series of pictures of objects that were either the exact same, similar or different from the day before. The participants had to decide on each photo and try and remember which photo was there the day before. It was concluded that the participants who were given 200mg and 300mg tablets of caffeine got the highest results. More participants from the group that received caffeine were able to correctly identify the new images as "similar" to previously viewed images versus erroneously citing them as the same object. The brain's ability to recognize the difference between two similar but not identical items, called “pattern separation” (Borota), reflects a deeper level of memory retention, the researchers said (Favila). The questions now is why? There is an expression that happens in our brain called the Brain-Derived Neurotrophic Factor or BDNF. BDNF is a secreted protein in the human brain that affects the synapses in our brain and helps with consolidation, but more specifically, pattern separation. Caffeine acts as a support system which helps BDNF build up stronger and faster, thus giving us evidence that caffeine can help consolidate memory in a much deeper way (Genetics Home Reference). One last notable experiment done to test for caffeine’s effect as a cognitive enhancer was published in the journal Psychopharmacology. A research team led by Harris R. Lieberman did a study to see if caffeine would enhance a Navy SEAL’s cognitive performance in a stressful and sleep deprived state. The researchers had 68 Navy SEAL volunteers that would receive either 100, 200, or 300mg of caffeine, or a placebo. The SEALs were given these pills after 72 hours of no sleep and exposure to stressful situations. Tests including visual reaction time, a visual vigilance test, a matching memory test, and a marksmanship test, along with a mood and saliva test. These tests were conducted one hour after receiving the pills and then again at the eight hour mark. The data showed improvement by taking the 200mg and 300mg pill of caffeine in visual reaction time, the visual vigilance test, self-reported fatigue, and alertness. These improvements were greatest at the one hour mark and still significant at the eight hour mark. The other tests did not receive results that were improved. The conclusion done by Lieberman and his team stated that a 200mg dose of caffeine will increase cognitive performance (Lieberman).

         Also, another powerful, positive effect of caffeine is on the mind. It is the power that it has to help ward off the disease known as Alzheimer’s disease, or medically known as Dementia of the Alzheimer’s Type. Alzheimer’s disease is a neurodegenerative disease in the brain, which simply put means that the brain’s cells are dying. The brain then begins to shrink and in-between nerve cells and connections are found certain molecules called amyloid plaques. There is a specific one called beta-amyloid which seems to be a major cause of Alzheimer’s disease (MacGill). This is where caffeine comes into play. Scientists and many researchers have done projects on mice to find out the effects of caffeine and how it may help control Alzheimer’s disease. Mice with Alzheimer’s disease that were given caffeine in their drinking water from young adulthood into older age showed protection against memory impairment and lower brain levels of the beta-amyloid, which is thought to be the central pathogenesis for Alzheimer’s disease. In the research project, the researchers tested mice with many different substances. The main substances were that of caffeinated coffee, decaffeinated coffee, and just normal caffeine. The research team was trying to find out if caffeine truly was the reason for the slowing of the progression of Alzheimer’s disease. In the results, the researchers only found that the caffeinated coffee as well as the caffeinated water, had the effects they were working towards. The effect which was being sought out was that of the reduction of the beta-amyloid. They found a direct link that caffeine indeed does suppress this beta-amyloid in the brain, which stops the mice from getting Alzheimer’s disease (Chu). Therapeutic models are now being done on humans to find the possibility of the same effects. Another test was done at the University of Eastern Finland, School of Medicine, which also researched the positive effects caffeine had towards Alzheimer’s disease. The basis of the University’s research was taking middle aged people (age 45-65) and giving the subjects on average, 3-5 cups of coffee a day. The conclusion from the experiment were exactly what happened in the study conducted by Johns Hopkins University. The majority of the results showed the middle aged people had a 65% decline in risk of contracting Alzheimer’s disease (Eskelinen). The results are very clear on how caffeine truly does help at preventing cognitive decline and helps to ward off Alzheimer’s disease.