- Alcohol is the world's most popular drug and has been a part of human culture for at least 9,000 years.
- Alcohol's effects on the brain range from temporarily limiting mental activity to sustained brain damage, depending on levels consumed and frequency of use.
- Understanding how alcohol affects your brain can help you determine what drinking habits are best for you.
Alcohol has enjoyed a near universal presence across human societies. Our ancestors began experimenting with alcohol fermentation at least 9,000 years ago and incorporated such heady drinks into their ceremonies, celebrations, social gatherings, and even medical practices. Today, alcohol is the most popular drug in the world. We use it to destress, to cheer us up, and to lubricate social interactions.
But why have people across cultures and through the ages enjoyed alcohol so much? It's all in how alcohol interacts with the human brain.
To see how alcohol affects the brain, let's perform a little thought experiment. Imagine you're at your favorite haunt, and you order a drink. It doesn't matter if it is wine, beer, or a cocktail. As far as our brains are concerned, alcohol is alcohol is alcohol. (Our waistlines, however, have another opinion on the matter.)
You ease into the booth, have a few sips, and enjoy some chitchat. You polish off your drink as a sense of relaxation disperses across your consciousness. Here's what's going on inside that head of yours.
Alcohol inbound
To get to the brain, alcohol must first be absorbed into your body through the GI tract. Most of the booze will be sopped up by your small intestines, where epithelial cells send it into the bloodstream. If you are drinking on an empty stomach, the alcohol beelines to the small intestine, and you'll feel its effects wash over you quite suddenly.
But if you enjoyed some pub grub with your drink, you'll notice the effects take longer to hit you. That's because your pyloric sphincter is closed to allow the stomach to digest the food. While your stomach absorbs some of the alcohol, it can't manage the job as effectively as your intestines.
Once in the bloodstream, the alcohol moves throughout your body. Your liver begins metabolizing what alcohol it can, but it can only manage so much at a time. On average it can handle one standard drink per hour, but this rate is highly dependent on you as an individual. Some people process their alcohol faster, others slower.
For the record, the United States health organizations measure one standard drink as 1.5 ounces of distilled spirits (at roughly 40 percent alcohol by volume, or ABV), 5 ounces of wine (at roughly 12 percent ABV), and 12 ounces of beer (at roughly 5 percent ABV).
Since you are drinking out, you'll need to pay attention to how much you've consumed in standard measurements. If you ordered a pint of your favorite IPA, for example, you probably consumed 16 ounces of beer at 7.5 percent ABV. You ordered one drink, but your liver is handling closer to two standard drinks.
But hey, it's the weekend, and you decide to belly up to the bar and order another round.
At this point, you're consuming alcohol faster than your liver can metabolize it, and the excess is accumulating in your bloodstream, increasing your blood alcohol concentration (or BAC). As the alcohol rides your bloodstream, it eventually makes its way to your brain, where it passes the blood-brain barrier and begins interacting with your neurons.
How alcohol affects your brain
Women wearing Bavarian folk dresses and headwear enjoy beer during Oktoberfest.
(Photo by Sean Gallup/Getty Images)
Alcohol inhibits activities in the brain. This is why it is known as a "depressant" — not because it makes you feel dispirited but because it reduces, or depresses, mental processes (compared to stimulants like caffeine that increase them). It manages this feat by tweaking with your brain signals.
Put simply, your nervous system relies on two types of signals: excitation and inhibition. Think of them as your personal binary code. An excitatory signal tells a neuron to fire up; an inhibitory signal tells a neuron to stay sedate. Chemical messengers called neurotransmitters are responsible for these signals. Glutamate and GABA are the primary neurotransmitters for excitatory and inhibitory signals, respectively.
As you're enjoying your second drink, the alcohol is hindering your glutamate neurotransmitters while pumping up the GABA. Basically, it's telling your brain to chill out, and you perceive this mental inactivity as a drowsy, easygoing relaxation.
The alcohol is also increasing your brain's output of dopamine, another neurotransmitter that serves many functions, one of which is to control your brain's reward center. A sensation or experience that releases dopamine tells your brain, "Hey, this is going to feel good. Remember this experience because we'll want do this again sometime."
Dopamine is why we experience drinking as fulfilling and also why it can prove habit forming. One study showed that people with a family history of alcohol abuse release more dopamine than nondrinkers simply in expectation of a quaff.
At this point the chemical pickling process has intensified, and your mental inactivity starts to affect the various structures of your brain. As these brain structures switch from active to less active, you feel a variety of different effects.
Your prefrontal cortex, for example, is your mind's executive and plays key roles in decision-making, self-management, and social behavior. As this region's activities slow down, you'll find you are more socially adventurous but also less cautious and prone to impulsive decisions.
Alcohol impairs your cerebellum, which regulates balance and motor functions. The more you drink the more you must concentrate to perform motor functions as basic as walking. A cock-eyed cerebellum also stifles your reaction time and is the reason why drinking and driving is so dangerous.
Then there's the hippocampus, the brain's hard drive. Even small amounts of alcohol can make memories slippery to hold on to. Drink enough and you'll find large portions of the evening's events completely wiped.
Two (or more) drinks over the line
Depending on how much you drink, you can end up anywhere from squiffy to chemically inconvenienced to full-on drunk. But these are only the short-term effects. Alcohol can continue to alter your mind well beyond your morning hangover.
The brain is an incredibly adaptive organ, so the more often you drink the better it learns to compensate for alcohol's effects. This is why long-time drinkers have to drink more to maintain the same buzz. Drink heavily enough for long enough, and your brain's compensation will shift into normalcy, resulting in alcohol dependence. So, the more often you drink the more severely alcohol changes your brain.
Light drinking can be part of a healthy lifestyle and may even confer some health benefits. One study found that light drinkers — those who consume less than three drinks per week — have a lower risk of cancer than moderate to heavy drinkers and even nondrinkers. Of course, the researchers warn that the "evidence should not be taken to support a protective effect of light drinking," so teetotalers needn't get their drink on just to mitigate their risk of cancer.
Moderate drinking — one drink a day for women, two for men — can also be part of a healthy lifestyle, but some research has suggested that even this rate of consumption can have ill health effects. One study found that moderate drinkers were more likely to develop hippocampal atrophy.
Heavy drinking, on the other hand, is undeniably harmful to your body and brain. Such levels of consumption can impact your cognitive abilities and lead to diminished gray matter, memory loss, loss of visuospatial abilities, and Wernicke-Korsakoff syndrome. Heavy drinking quite literally shrinks your brain.
Talk with your doctor
It's worth pointing out that our little thought experiment provides a general overview of how alcohol affects the brain. As with any drug, many factors influence how things shake out, such as a person's age, gender, genetic background, drinking history, and even level of education. Lifestyle choices such as whether you smoke or get enough exercise will also play in.f
Studies have suggested, for example, that women who are heavy drinkers are more vulnerable than men at developing cirrhosis, nerve damage, and brain damage — even if they engage in such levels of consumption for fewer years.
If you choose to drink, the best way to determine what habits are best for you is to speak openly and honestly with your physician.
Some scientists have studied near death experiences (NDEs) to try to gain insights into how death overcomes the brain. What they've found is remarkable, a surge of electricity enters the brain moments before brain death. One 2013 study out of the University of Michigan, which examined electrical signals inside the heads of rats, found they entered a hyper-alert state just before death.
Scientists are beginning to think an NDE is caused by reduced blood flow, coupled with abnormal electrical behavior inside the brain. So the stereotypical tunnel of white light might derive from a surge in neural activity. Dr. Sam Parnia is the director of critical care and resuscitation research, at NYU Langone School of Medicine, in New York City. He and colleagues are investigating exactly how the brain dies.
Our cerebral cortex is likely active 2–20 seconds after cardiac arrest. Credit: Getty Images.
In previous work, he's conducted animal studies looking at the moments before and after death. He's also investigated near death experiences. “Many times, those who have had such experiences talk about floating around the room and being aware of the medical team working on their body," Dr. Parnia told Live Science. “They'll describe watching doctors and nurses working and they'll describe having awareness of full conversations, of visual things that were going on, that would otherwise not be known to them."
Medical staff confirm this, he said. So how could those who were technically dead be cognizant of what's happening around them? Even after our breathing and heartbeat stops, we're conscious for about 2–20 seconds, Dr. Parnia says. That's how long the cerebral cortex is thought to last without oxygen. This is the thinking and decision-making part of the brain. It's also responsible for deciphering the information gathered from our senses.
According to Parnia during this period, "You lose all your brain stem reflexes — your gag reflex, your pupil reflex, all that is gone." Brain waves from the cerebral cortex soon become undetectable. Even so, it can take hours for our thinking organ to fully shut down.
Usually, when the heart stops beating, someone performs CPR (cardiopulmonary resuscitation). This will provide about 15% of the oxygen needed to perform normal brain function. "If you manage to restart the heart, which is what CPR attempts to do, you'll gradually start to get the brain functioning again," Parnia said. “The longer you're doing CPR, those brain cell death pathways are still happening — they're just happening at a slightly slower rate."
CPR may help retain some brain function for longer. Credit: Getty Images.
Dr. Parnia's latest, ongoing study looks at large numbers of Europeans and Americans who have experienced cardiac arrest and survived. "In the same way that a group of researchers might be studying the qualitative nature of the human experience of 'love,'" he said, "we're trying to understand the exact features that people experience when they go through death, because we understand that this is going to reflect the universal experience we're all going to have when we die."
One of the objectives is to observe how the brain acts and reacts during cardiac arrest, through the process of death, and during revival. How much oxygen exactly does it take to reboot the brain? How is the brain affected after revival? Learning where the lines are drawn might improve resuscitation techniques, which could save countless lives per year.
"At the same time, we also study the human mind and consciousness in the context of death," Parnia said, “to understand whether consciousness becomes annihilated or whether it continues after you've died for some period of time — and how that relates to what's happening inside the brain in real time."
For more on the scientific perspective on a near death experience, click here:
Elephants dilate their nostrils to create more space in their trunks, allowing them to store up to 5.5 liters (1.45 gallons) of water, according to their new study.
They can also suck up three liters (0.79 gallons) per second—a speed 30 times faster than a human sneeze (150 meters per second/330 mph), the researchers found.
The researchers wanted to better understand the physics of how elephants use their trunks to move and manipulate air, water, food, and other objects. They also wanted to learn if the mechanics could inspire the creation of more efficient robots that use air motion to hold and move things.
Photo by David Clode on Unsplash
While octopuses use jets of water to propel themselves and archer fish shoot water above the surface to catch insects, elephants are the only animals able to use suction both on land and underwater.
"An elephant eats about 400 pounds of food a day, but very little is known about how they use their trunks to pick up lightweight food and water for 18 hours, every day," says lead author Andrew Schulz, a mechanical engineering PhD student at the Georgia Institute of Technology. "It turns out their trunks act like suitcases, capable of expanding when necessary."
Sucking up tortilla chips without breaking them
Schulz and his colleagues worked with veterinarians at Zoo Atlanta, studying elephants as they ate various foods. For large rutabaga cubes, for example, the animal grabbed and collected them. It sucked up smaller cubes and made a loud vacuuming sound, like the sound of a person slurping noodles, before transferring the vegetables to its mouth.
To learn more about suction, the researchers gave elephants a tortilla chip and measured the applied force. Sometimes the animal pressed down on the chip and breathed in, suspending the chip on the tip of its trunk without breaking it, similar to a person inhaling a piece of paper onto their mouth. Other times the elephant applied suction from a distance, drawing the chip to the edge of its trunk.
Elephants inhale at speeds comparable to Japan's 300 mph bullet trains.
"An elephant uses its trunk like a Swiss Army knife," says David Hu, Schulz's advisor and a professor in Georgia Tech's School of Mechanical Engineering. "It can detect scents and grab things. Other times it blows objects away like a leaf blower or sniffs them in like a vacuum."
By watching elephants inhale liquid from an aquarium, the team was able to time the durations and measure volume. In just 1.5 seconds, the trunk sucked up 3.7 liters (just shy of 1 gallon), the equivalent of 20 toilets flushing simultaneously.
Soft robots and elephant conservation
The researchers used an ultrasonic probe to take trunk wall measurements and see how the trunk's inner muscles work. By contracting those muscles, the animal dilates its nostrils up to 30%. This decreases the thickness of the walls and expands nasal volume by 64%.
"At first it didn't make sense: an elephant's nasal passage is relatively small and it was inhaling more water than it should," Schulz says. "It wasn't until we saw the ultrasonographic images and watched the nostrils expand that we realized how they did it. Air makes the walls open, and the animal can store far more water than we originally estimated."
Based on the pressures applied, Schulz and the team suggest that elephants inhale at speeds comparable to Japan's 300-mph bullet trains.
Schulz says these unique characteristics have applications in soft robotics and conservation efforts.
"By investigating the mechanics and physics behind trunk muscle movements, we can apply the physical mechanisms—combinations of suction and grasping—to find new ways to build robots," Schulz says.
"In the meantime, the African elephant is now listed as endangered because of poaching and loss of habitat. Its trunk makes it a unique species to study. By learning more about them, we can learn how to better conserve elephants in the wild."
The paper appears in the Journal of the Royal Society Interface. The US Army Research Laboratory and the US Army Research Office 294 Mechanical Sciences Division, Complex Dynamics and Systems Program, funded the work. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the view of the sponsoring agency.
Source: Georgia Tech
Original Study DOI: 10.1098/rsif.2021.0215
Reprinted with permission of Futurity. Read the original article.
As he described it, “In my mind's eye I saw many, many things: children that I hadn't even had yet, friends that I had never seen but are now my friends. The thing that really stuck in my mind was playing an instrument". Then Tony landed on his head and lost consciousness.
When he came to at the hospital, he felt like a different person and didn't want to return to his previous life. Over the following weeks, the images kept flashing back into his mind. He felt that he was “being shown something" and that the images represented his future.
Later, Tony saw a picture of a saxophone and recognized it as the instrument he'd seen himself playing. He used his compensation money from the accident to buy one. Now, Tony Kofi is one of the UK's most successful jazz musicians, having won the BBC Jazz awards twice, in 2005 and 2008.
Though Tony's belief that he saw into his future is uncommon, it's by no means uncommon for people to report witnessing multiple scenes from their past during split-second emergency situations. After all, this is where the phrase “my life flashed before my eyes" comes from.
But what explains this phenomenon? Psychologists have proposed a number of explanations, but I'd argue the key to understanding Tony's experience lies in a different interpretation of time itself.
When life flashes before our eyes
The experience of life flashing before one's eyes has been reported for well over a century. In 1892, a Swiss geologist named Albert Heim fell from a precipice while mountain climbing. In his account of the fall, he wrote is was “as if on a distant stage, my whole past life [was] playing itself out in numerous scenes".
More recently, in July 2005, a young woman called Gill Hicks was sitting near one of the bombs that exploded on the London Underground. In the minutes after the accident, she hovered on the brink of death where, as she describes it: “my life was flashing before my eyes, flickering through every scene, every happy and sad moment, everything I have ever done, said, experienced".
In some cases, people don't see a review of their whole lives, but a series of past experiences and events that have special significance to them.
Explaining life reviews
Perhaps surprisingly, given how common it is, the “life review experience" has been studied very little. A handful of theories have been put forward, but they're understandably tentative and rather vague.
For example, a group of Israeli researchers suggested in 2017 that our life events may exist as a continuum in our minds, and may come to the forefront in extreme conditions of psychological and physiological stress.
Another theory is that, when we're close to death, our memories suddenly “unload" themselves, like the contents of a skip being dumped. This could be related to “cortical disinhibition" – a breaking down of the normal regulatory processes of the brain – in highly stressful or dangerous situations, causing a “cascade" of mental impressions.
But the life review is usually reported as a serene and ordered experience, completely unlike the kind of chaotic cascade of experiences associated with cortical disinhibition. And none of these theories explain how it's possible for such a vast amount of information – in many cases, all the events of a person's life – to manifest themselves in a period of a few seconds, and often far less.
Thinking in 'spatial' time
An alternative explanation is to think of time in a “spatial" sense. Our commonsense view of time is as an arrow that moves from the past through the present towards the future, in which we only have direct access to the present. But modern physics has cast doubt on this simple linear view of time.
Indeed, since Einstein's theory of relativity, some physicists have adopted a “spatial" view of time. They argue we live in a static “block universe" in which time is spread out in a kind of panorama where the past, the present and the future co-exist simultaneously.
The modern physicist Carlo Rovelli – author of the best-selling The Order of Time – also holds the view that linear time doesn't exist as a universal fact. This idea reflects the view of the philosopher Immanuel Kant, who argued that time is not an objectively real phenomenon, but a construct of the human mind.
This could explain why some people are able to review the events of their whole lives in an instant. A good deal of previous research – including my own – has suggested that our normal perception of time is simply a product of our normal state of consciousness.
In many altered states of consciousness, time slows down so dramatically that seconds seem to stretch out into minutes. This is a common feature of emergency situations, as well as states of deep meditation, experiences on psychedelic drugs and when athletes are “in the zone".
The limits of understanding
But what about Tony Kofi's apparent visions of his future? Did he really glimpse scenes from his future life? Did he see himself playing the saxophone because somehow his future as a musician was already established?
There are obviously some mundane interpretations of Tony's experience. Perhaps, for instance, he became a saxophone player simply because he saw himself playing it in his vision. But I don't think it's impossible that Tony did glimpse future events.
If time really does exist in a spatial sense – and if it's true that time is a construct of the human mind – then perhaps in some way future events may already be present, just as past events are still present.
Admittedly, this is very difficult to make sense of. But why should everything make sense to us? As I have suggested in a recent book, there must be some aspects of reality that are beyond our comprehension. After all, we're just animals, with a limited awareness of reality. And perhaps more than any other phenomenon, this is especially true of time.
Steve Taylor, Senior Lecturer in Psychology, Leeds Beckett University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
