Caffeine Kick: How Does Drinking Coffee Affect Your Brain?
Do you wake up and smell the coffee? Some individuals cannot imagine surviving a whole day without a Joe, and in the US, over 85% of Americans adults are thought to consume caffeine in the form of drinks, foods and supplements. Whether it’s first thing in the morning or during the afternoon slump, a strong coffee is normally the most convenient solution to pull yourself from the verge of slumber to alive and kicking. The chemical component of coffee and other energy-boosting products responsible for this jump-start is caffeine, and the mechanism by which it stops you nodding off in that warm meeting room is to prevent the ‘I’m sleepy’ signals being activated in your brain. Although our latte sipping is normally used as a sleep-staving remedy, caffeine could impact your brain functions in a variety of ways from improving productivity to inducing anxiety. So, stick the kettle on and settle down over your cuppa to learn about the impact your favourite hot beverage could be having on your brain.
Wake me up before you go-go: Caffeine in the Brain
There is nothing quite like the smell of freshly ground coffee and the brewing by baristas is almost wizardry; making the potion of life for your half-asleep brain. Although not quite the magic beans sold to Jack by the giant, coffee beans are a compact blend of chemicals which differs from brand to brand. There are thousands of chemicals in each bean to give coffee its distinctive smell, earthy flavour and – most critically – kick. The levels of the majority of these chemicals are so low in coffee that their effects on your body are still being explored. However, one of these bad boys is known to enter your blood stream, pass into the brain and wake you up: caffeine.
Caffeine (also known in chemical terms as the really catchy 1,3,7-trimethylxanthine) acts as a sleep inhibitor by entering a competition with adenosine; a chemical which tells your brain you are tired. Caffeine and adenosine both bind to brain cells (neurons) at the same specific points, known as receptors. When adenosine binds, the neuron is informed the body is tired and needs to go to bed. The levels of adenosine rise steadily throughout your day so by the time you are brushing your teeth, your brain is ready to drop off to the land of nod. As you enter dreamland, adenosine begins to clear from its binding sites on neurons meaning when you wake up, your body should no longer feel tired. And if you experience morning grogginess, this could partially be down to excess adenosine still remaining attached to your neurons, making you want to go straight back to sleep!
If you drink a coffee, caffeine shortly enters the brain and starts to compete with adenosine for these receptor spaces. Once a caffeine molecule binds to a receptor, adenosine cannot bind there and hence, the sleepy signals are stopped in their tracks. Caffeine hangs around for a good few hours in the body which is why you are advised to not drink coffee later in the day to ensure a good nights sleep. Also, caffeine’s mechanism of action explains why coffee does not have as good an effect in keeping some people awake in the evening or night – if your adenosine levels are already high and you drink a coffee, there is limited space for the caffeine molecules to bind. This means the caffeine cannot stop the ‘I’m tired’ signals as well as it can when you have your double shot, sugar-free vanilla soya latte first thing in the a.m.
I’m Buzzing: The Cognitive Effects of Caffeine
How do you feel after you have had a caffeinated drink? More energetic & less sleepy is the normal short-term response to a shot of espresso but long term, caffeine consumption could be doing a lot more than allowing you to not fall asleep at your desk. There are many myths and statements made about the effects coffee drinking can have on your head, but does the scientific evidence hold up?
Productivity & Memory
Two cognitive associations linked to coffee consumption is an improvement in productivity and memory. In the short-term, coffee intake has been correlated with an increase in alertness and arousal following consumption, with caffeinated individuals showing faster reaction times in a cognitive test compared to test subjects given decaf coffee. With memory, the picture is slightly more fuzzy. A recent scientific study reported an increase in memory-associated tasks in young people at their ’non-optimal’ working hours (aka the morning) immediately following coffee consumption, but due to the close link between short-term memory and attention, it is hard to form a clear cut conclusion on the targeted mechanism in these types of studies. However, the mechanisms of long-term memory are completely different to short, and the link between its improvement and drinking coffee have tried to be measured experimentally. For example, when adult rats are fed the equivalent of 10 cups of coffee per day for around 2 months, they perform better on cognition tests than rats with less or no coffee in their diet. In humans, some studies argue for a similar trend, with coffee-intake over time favouring enhanced verbal memory, and one study points out this trend is only seen in elderly women. But, other population studies attempting to link coffee intake and memory function have found no such results. With these human studies, it is hard to tease out the direct relationship between coffee consumption and cognition due to various other effecting factors like genetics, overall health and lifestyle choices. What needs to be shown is a biological mechanism underlying how a single component or multiple chemicals in coffee can directly alter memory-related processes in the brain.
A huge problem in our ever-ageing society is the number of people contracting late-life diseases such as dementia and Parkinson’s. Some research into the link between developing dementia and drinking coffee have found that individuals who drink 3-5 cups a day in their mid-life have a lower chance of going on to develop dementia, but the numbers of people who went on to develop dementia (48 people) where low compared to the population studied (1408 people). In experimental set ups, specific chemicals found in coffee have been shown to prevent the formation of the large plaques associated with Alzheimer’s disease in test tubes, and mice with Parkinson’s-like symptoms had improved behaviour and reduced brain build-up of aggregates associated with Parkinson’s when treated with caffeine plus another coffee chemical (EHT). Although this work favours the idea there could be a direct mechanism on how coffee could reduce the likelihood of contracting a late-life neurodegenerative disease, the set ups are not transferable to real life conditions. Therefore, we really need to show if coffee has mechanistic effects in the human brain in order to confirm its relationship with reducing dementia and movement-related brain disorders.
Ever had one too many cups of coffee and felt extremely anxious? That is because caffeine is a stimulant of your sympathetic nervous system – the collection of nerves involved in your ‘fight or flight’ response. You may notice that post-coffee gulping, your heart beats faster, your breathing quickens and your alertness peaks up. If you are an individual with anxiety, this excessive stimulation of these ‘fight or flight’ functions can trick your brain into an anxiety-induced state as the effects of caffeine mirror those of an anxiety attack. It has been shown that excessive caffeine intake in teenagers, who are considered to be a sensitive group to develop anxiety, results in a significant increase in levels of anxiety and depression, even after controlling for diet, where the subjects live and lifestyle factors. Furthermore, individuals who self-identify as feeling jittery and anxious following too much coffee where shown to have higher levels of mutations in their adenosine receptor genes, suggesting a difference in how caffeine interacts at the adenosine binding sight in neurons could predispose specific people to feeling more than just buzzed after a shot of espresso. Together, these studies give us an idea of how caffeine intake can heighten anxiety in sensitive groups and potentially gives an explanation why some people are more sensitive to coffee-related anxiousness than others.
Now you are in the know about what happens to your brain after a cup of Joe. Caffeine is the key to keeping you awake by stopping those adenosine-associated sleep signals taking wind. The long-term affects of how coffee consumption impacts your brain are still being explored, with trends in improved cognition and memory coming through alongside a potential reduction in late-life brain disorders. But at the minute, these results are not clear cut and much more through research is being conducted to really understand the mechanisms involved in these links. Plus, as coffee drinking is so engrained into our everyday lives, it is much harder to study its effects in isolation.
Next time you are sipping on a skinny caramel macchiato, think about the epic battle between caffeine and adenosine in your brain to keep you from drifting off on the train and missing your stop.
Julia xoxo (@Julia.ravey.science)
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