Effects of drinking water on the brain


Chapter 2

Literature Review 2.0 Effects of water on the body.

2.0.1 Energy level.

In order to increase energy level, the human body has to be kept hydrated constantly. The human brain is mostly made up of water hence it is of utmost importance that we keep our brain hydrated to obtain maximum productivity and alertness (Simonds,N.D). A well hydrated body will create higher amounts of oxygen levels present in the body, which will provide us with more energy. The increased energy levels will make a person more alert and even lift their mood (Bernstein, 2012). Even if the level of water in the body is at least one percent below the optimal water level, the person will feel fatigue (Chasey,N.D).

2.0.2 Effects of drinking water on the brain

Water provides the brain with electrical energy in order for all the functions of the brain to be carried out, which includes thought and memory processes. It has also been proven to help a person “be more focused, has the ability to experience greater clarity creativity and think faster” (Bailey, 2013). A study was carried out on participants who drank three cups of water which was 24 ounces, or 775 milliliters. After taking a battery of cognitive tests, the participants who drank water performed better on a test that measured reaction time compared with those who did not drink water. The researchers contemplated that the thirst sensation of the participants may have taken some attention away from their task at hand, resulting in a slower response time (Rettner, 2013). However, in another study, water consumption did not affect the results on other tests of cognition much, such as memory of words (Rettner, 2013).

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2.1Effects of Caffeine on the Brain


Adenosine is a naturally occurring neurotransmitter in our brain. Adenosine is produced as long as we are awake as our brain has neurons. These neurons are specialised cells that transmit nerve impulses from one neuron to another in order for us to carry out daily activities.

Adenosine is a by product of the functioning neuron. The Adenosine produced will then bind to adenosine receptors which is a method used by our body to detect the amount of adenosine in our body. When the amount of adenosine in our body reaches a certain amount, the information will be sent to our brain or spinal cord causing us to feel tired.

Caffeine, like the Adenosine, also binds to the Adenosine Receptors. Compared to adenosine molecules, Caffeine molecules have the capability to bind faster to adenosine receptors. As such, when the Caffeine molecules are binded before the Adenosine molecules, the Caffeine molecules blocks the Adenosine Receptors from causing any effects of tiredness or sleepiness in our body (Goodwin, 2013).

caffeine-diagram.jpg Figure 2.1: In the brain Caffeine (C) binds faster to adenosine receptors. Adenosine (A), which is a natural sedative, will be prevented from attaching itself therefore, causing alertness.


Since caffeine prevents the adenosine from binding with the adenosine receptor, uncontrolled neuron activation will occur (N.A, 2009). This will cause the pituitary gland to release a certain hormone into the bloodstream which will affect the adrenal glands to produce adrenaline which is a “flight or fright” hormone (Veracity, 2005). The flight or fright hormone is our body’s way to prepare ourselves to “fight” or “flee” in situations that make us feel as if we are under attack, threatened or harmed the response produced is primitive, automatic and an innate (Neimark, N.D).Adrenaline will also cause an increase in muscle tension, blood pressure, respiration, heart rate, metabolism, mental alertness, emotional and a decrease in digestion, sex hormones, mental creativity, emotional stability will be decreased (Bay, N.D)

2.2Importance of taking caffeine in moderation

2.2.1Caffeine Tolerance

Tolerance is the reduced stimulus towards a drug, which will occur when the drug is repeatedly used until the body has adapted to its presence (Hussar, 2013). Therefore a higher dose of drugs will be needed to achieve the same outcome achieved initially (NIH, 2007).

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Since caffeine is a drug, too much intake of it will cause us to be tolerant to it. This is due to the gradual creation of adenosine receptors by the brain cells to re-balance the adenosine receptors that have been blocked by caffeine molecules (Stromberg,2013). Eventually more adenosine receptors will be produced, causing the need of more caffeine molecules to block the extra adenosine receptors created in order to achieve the same effect that was intended (Stromberg,2013). Off and on, drinkers require little amounts of caffeine for optimal performance during cognitive tasks while habitual drinkers require a higher dosage of caffeine to achieve the same effect (Papadeli, Papadelis, Louizos, Tziampiri, 2002).

2.2.2Effect of drinking caffeine near bed time

For a regular drinker the ingestion of caffeine will not affect much but if a person is not a regular drinker he or she may find it difficult to fall asleep (Keeffe, 2011). These problems usually arise during the digestion of caffeine in the body. Caffeine will be mainly digested in the liver by a liver enzyme to produce Theophylline, Theobromine, and Paraxanthine separately (Gabriel, 2000). Paraxanthine molecule has almost the same structure and effect as caffeine on the brain (Gabriel, 2000). If the intake of caffeine increases, the amount of caffeine and Paraxanthine that will be accumulated in the body will also increase (Keeffe, 2011). Adenosine that has been produced in the body can only be removed through sleep. Therefore insufficient sleep will cause tiredness and unproductivity throughout the following day which will lead to another cup of coffee to overcome that tiredness. The more caffeine ingested, the more adenosine and caffeine molecules will be accumulated in the body by night. The half life of one dosage of caffeine is 3-7 hours but if more caffeine is accumulated in our body the half life of caffeine can increase from 11-96 hours or even days (Keeffe, 2011).

2.2.3Effects of high doses of caffeine on cognition.

It is important to take caffeine in moderation which is about 200 to 300 mg per day (Rivers, 2012). If caffeine is taken in excess which is more than 500 to 600 mg it will disturb our body systems as caffeine is a drug that can cause our adrenal glands to release adrenaline. Therefore, a person may suffer from insomnia, nervousness, restlessness, irritability, upset stomach, fast heartbeat and muscle tremors if adrenaline is released in excess in a person’s body (Mayo Clinic, 2014). The more severe symptoms of caffeine overdose is trouble of breathing, vomiting, hallucinations, confusion, chest pain, irregular or fast heartbeat and uncontrollable muscle movements, convulsions (Rivers, 2012). Caffeine will also block our adenosine receptors therefore too much caffeine will result in sleep deprivation. A normal person needs about 7 to 8 hours of sleep. Sleep deprivation is caused by the disruption in the sleep cycles which may eventually cause to the feeling of tiredness, moody and depression. Sleep deprivation will also disrupt a person’s performance and alertness during the day (Mayo Clinic, 2014).

2.2.4Effect’s of low doses of caffeine on cognition.

A study was once done to study the effects of low doses of caffeine on cognition of 11 males and 12 females aged between 18 and 56. The respondents were either given 0, 12.5, 25, 50 or 100 mg of caffeine. Their performance was tested by using a test battery that consisted of a long duration simple reaction time test, a rapid visual information processing task and a mood questionnaire. All the doses of the caffeine had influenced cognitive performance, there were minimal differences between the dosage size. The effects of caffeine were more obvious in those that were regular caffeine consumers. After a night without caffeine, the participants cognitive performance, mood and thirst has been affected even at doses same as and even lesser than the amounts of caffeine contained in a single serving of beverages containing caffeine (Smit, Rogers, 2000).

2.3Effect of caffeine on Memory

2.3.1Information processing model processes memory

The Information Processing Theory assumes that human memory is formed in the same way that a computer processes information. There are 3 stages of memory which are sensory memory, short-term memory, and long-term memory (Cherry, N.D).. A computer receives information from external devices codes information followed by storing the information into its memory and uses the information to produce an output (McLeod, 2008). In humans, memory is formed by the input device called the sensory register, which consist of our five senses namely taste, touch, sight, hearing and smell that enables us to receive information from our surroundings. The information received by our sensory memory will then undergo selective attention and the selected memory will be stored into our short term memory. Short term memory information that has been selected will be held temporarily so that it can be used, removed or transferred into our long term memory. Information that is stored in the long term memory can be stored for a very long time.

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2.3.2Short term memory and working memory

Short term memory and working memory are often used interchangeably (Posit Science, 2015). The ability to store information temporarily for immediate retrieval and removal is short term memory, while working memory is the processing of information stored in the short term memory for manipulation (Examined existence, N.D). Information that has undergone selective attentionduring sensory memory will be generated in the short term memory (Cherry, N.D). The function of Short-term memory is to choose, launch and discontinue information-processing functions which consist of encoding, storing and retrieving data to and from the long term memory (Medicine.net, 2013). Short term memory has limited capacity and can only store about seven plus minus 2 items and it also has limited duration as it is very fragile and can be lost whenever there are distractions (Mc Leod, 2009).

2.3.3The magic number seven plus and minus two

Miller discovered in 1956 that an average adult can store about seven plus minus two items in their short term memory (Bilash, 2011). If information is chunked together, we will be able to store more information (Mc Leod, 2009).

2.4Short term memory test


The Memory Assessment Scale has three areas of cognitive function

MAS is a comprehensive battery that has the ability to assesses a person’s short-term, verbal and visual memory functioning. In order to assess memory, this battery has 12 subtest that are based on the 7 memory task which are Verbal Span, List Learning, Prose memory, Visual Span, Visual Recognition, Visual Reproduction and Names-Faces. The “verbal span test” is a test whereby a series of numbers will be read forward and backwards to the participants slowly beginning with 2 numbers to 3 numbers to 4 numbers up till 9 numbers, participants are then required to repeat the numbers said by the examiner in the correct order.

2.4.2Wechsler Memory Scale

A set of numbers will be announced through headphones to the participants at the rate of 1 word per second. Digits are chosen at random without repetition up to of 9 digits (when participants has a gone more than 9 numbers single digit will be doubled). The successive digits cannot occur in ascending or descending order with equal step sizes. A notification will be shown to alert the participants after the final digit at an interval of 1.0 s, so that the participants will know when to repeat the sequence said. The digit sequence was shown on the examiners monitor during its list presentation and the response of the participants were analysed by the examiner using the computer keyboard. The participant is then told to repeat the numbers that were shown or read to them.

2.4.3 Digit span test

A list of numbers are shown or read out to the participants. This process is continued until the participant cannot remember either the full sequence of numbers or the correct order of numbers. In the reverse trial of the Digit Span a series of numbers will be read to the participant and the participant will be asked to repeat the number sequence that was said by the examiner in the reverse order. This sequence of number is continued until the participant makes an error. Participants are given two chances for each sequence of number because both forward and reverse trials are given twice. The score of the Digit Span test is calculated by adding the total number of correct sequences, backwards and forwards. This test is also scored differently for a range of ages. For an adult to score an average score is about six numbers both backwards and forwards. While above average is anything over seven. Because of time limits, the computerized version of this test will only be able to measure the participant’s ability to repeat back a number sequence in the forward order. The 15 minute time limit should not greatly affect the results. An accurate result will be obtained and the participant’s working memory can be viewed (Mendez,N.D).


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