What does caffeine do to your brain

Coffee and tea are well-loved drinks that contain caffeine, a chemical component that may confer both beneficial and adverse effects on our health. Dr Ooi Yau Wei, cardiologist at Mount Elizabeth Novena Hospital, explains the advantages and disadvantages of caffeine.

The effects of caffeine are manifold, affecting various parts of the body, including the brain, heart, stomach and hormones.

Our bodies contain adenosine, a hormone that is responsible for slowing the nervous system and relaxing the body. When we drink caffeine, it blocks the effects of adenosine, resulting in greater alertness, mental energy and concentration.

Caffeine and your brain

Caffeine has been shown to influence cognition and mood. Its effects, however, vary depending on the amount of caffeine and time of consumption.

In rested individuals, caffeine in low and moderate doses improves vigilance and reaction time. In sleep-deprived individuals, caffeine has positive effects on learning and decision-making. Individuals who are habitual consumers of coffee and tea have been shown to perform better on various tests of cognitive performance such as reaction time and visual-spatial skills.

Caffeine can alleviate headache symptoms significantly. It is frequently used alone or in combination with other headache treatment medications. However, regular caffeine consumption can also lead to chronic migraine and analgesic rebound headaches (headaches caused by overusing headache/pain-relief medication).

Caffeine and your heart

Low to moderate coffee consumption (up to 3 cups per day) has been shown to protect against heart attacks. However, taking more than 3 cups of caffeine a day may trigger coronary (heart artery) problems and heart rhythm irregularities in people with underlying heart disease. Thus, patients at risk of heart problems should avoid drinking large quantities of caffeine.

For people who seldom take caffeine, an episode of caffeine intake can raise their blood pressure significantly. However, there is little or no acute effect on habitual coffee drinkers.

Downsides of caffeine

For all the good that caffeine does, caffeine intake has its downsides too.

Since caffeine can boost mental and physical energy, it is little wonder that many individuals turn to caffeine regularly to maintain their active, busy lifestyles. However, consuming high levels of caffeine may lead to symptoms such as headache, rapid heart rate, anxiety, tremors, and insomnia.

In the long term, caffeine dependence may lead to generalised anxiety disorder, nervousness, insomnia, irritability, and even panic attacks.

Caffeine has also been linked to a higher risk of osteoporosis. Research suggests that high coffee intake may be associated with lower bone density and increased fracture risk in women, particularly those with low calcium intake. One way to counter this is to increase intake of calcium-rich food, or calcium-fortified drinks.

Signs of caffeine withdrawal

Like all stimulants, caffeine can be addictive and give you withdrawal symptoms when you stop taking it. Here's how to tell if you're undergoing caffeine withdrawal:

If you experience

• Headache
• Tiredness/fatigue
• Decreased energy
• Decreased alertness
• Drowsiness/sleepiness
• Depressed mood
• Difficulty concentrating
• Irritability
• Fuzzy/foggy mind

How much caffeine should I take?

For most adults, consumption of up to 400mg of caffeine a day appears to be safe. Here’s the amount of caffeine in our common drinks.

• Coffee (235ml): 102 – 200mg
• Espresso (30ml): 30 – 90mg
• Tea (235ml): 40 – 120mg
• Coke (355ml): 35 – 47mg
• Mountain Dew (355ml): 118mg

The average US adult's coffee consumption is about 2 cups per day, which is the equivalent of approximately 280mg of caffeine, although coffee varies greatly in caffeine content. Individuals who consume 4 or more cups of coffee daily are considered to be heavy coffee drinkers.

Given all the benefits and risks caffeine might bring, the research suggests that the pros still outweigh the cons, provided you do not have any existing medical problems which can potentially be made worse with caffeine. When taken in moderate amounts, caffeine can improve mood and performance. Perhaps your daily cup has more benefits than you thought.

Coffee, cola or an energy drink: caffeine is the world's most widely consumed psychoactive substance. Researchers from the University of Basel have now shown in a study that regular caffeine intake can change the gray matter of the brain. However, the effect appears to be temporary.

No question -- caffeine helps most of us to feel more alert. However, it can disrupt our sleep if consumed in the evening. Sleep deprivation can in turn affect the gray matter of the brain, as previous studies have shown. So can regular caffeine consumption affect brain structure due to poor sleep? A research team led by Dr. Carolin Reichert and Professor Christian Cajochen of the University of Basel and UPK (the Psychiatric Hospital of the University of Basel) investigated this question in a study.

The result was surprising: the caffeine consumed as part of the study did not result in poor sleep. However, the researchers observed changes in the gray matter, as they report 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.

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 period, 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).

Sleep unaffected, but not gray matter

Data comparison revealed that the participants' depth of sleep was equal, regardless of whether they had taken the caffeine or the placebo capsules. But they saw a significant difference in the gray matter, depending on whether the subject had received caffeine or the placebo. After 10 days of placebo -- i.e. "caffeine abstinence" -- the volume of gray matter was greater than following the same period of time with caffeine capsules.

The difference was particularly striking in the right medial temporal lobe, including the hippocampus, a region of the brain that is essential to memory consolidation. "Our results do not necessarily mean that caffeine consumption has a negative impact on the brain," emphasizes Reichert. "But daily caffeine consumption evidently affects our cognitive hardware, which in itself should give rise to further studies." She adds that in the past, the health effects of caffeine have been investigated primarily in patients, but there is also a need for research on healthy subjects.

Although caffeine appears to reduce the volume of gray matter, after just 10 days of coffee abstinence it had significantly regenerated in the test subjects. "The changes in brain morphology seem to be temporary, but systematic comparisons between coffee drinkers and those who usually consume little or no caffeine have so far been lacking," says Reichert.

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Materials provided by University of Basel. Note: Content may be edited for style and length.

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