Low to Moderate Alcohol Consumption & Neurodegeneration
A commonly asked question about alcohol consumption and its effects on the brain is whether or not low to moderate amounts, such as one or two drinks per day, cause degeneration of neurons or nerve cells. It has long been known that high levels of alcohol consumption, such as 12 to 24 drinks per week or more, can certainly cause neurodegeneration, specifically in the neocortex, which houses associative memories, the ability to think and plan, and the ability to regulate primitive drives according to context.
A recent study titled “Associations Between Alcohol Consumption and Gray and White Matter Volumes in the UK Biobank” examined the brains of over 35,000 generally healthy middle-aged and older adults in the United Kingdom who were drinking various amounts of alcohol. The study found that even for people who were drinking low to moderate amounts of alcohol, such as one or two drinks per day, there was evidence of thinning of the neocortex and loss of neurons in other brain regions.
It is important to note that the study defines chronic intake as an average of one or two drinks per night, which can be different than people’s perception of “chronic” as high levels of intake like five or ten drinks a night or drinking every night.
This study suggests that even consuming as little as seven glasses of wine per week can lead to degeneration of the brain. Though it’s also worth mentioning that there are ways to mitigate the neuronal loss caused by alcohol consumption. These findings are important for people who are interested in making informed decisions about their alcohol consumption.
Inebriation: Top-Down Inhibition, Impulsivity & Memory Formation
Alcohol is a substance that has been consumed by humans for thousands of years and its effects on the body have been studied extensively. But one question that often comes up is the effect of low to moderate amounts of alcohol on the brain, in particular, whether or not it causes degeneration of neurons or nerve cells.
It’s been known for many years that high levels of alcohol consumption, 12 to 24 drinks per week or more, causes neurodegeneration, in particular, of the neocortex, the outer layers of the brain that house associative memories, the ability to think and plan, and the ability to regulate primitive drives according to context.
Recently, a study titled “Associations Between Alcohol Consumption and Gray and White Matter Volumes in the UK Biobank” looked at the brains of more than 30,000 and even more than 35,000 generally healthy middle-aged and older adults in the United Kingdom who were drinking various amounts of alcohol. The study found that even for people that were drinking low to moderate amounts of alcohol, one or two drinks per day, there was evidence of thinning of the neocortex, loss of neurons in the neocortex, and other brain regions.
Drinking a lot, having three or four drinks per night every night of the week is clearly bad for the brain, but now this study shows that even drinking small amounts, such as one or two drinks per night, can have detrimental effects on the brain. It’s important to note that while drinking alcohol, one is consuming a toxic substance, ethanol, which has to be converted into something else because it’s toxic to the body. The body deals with this by using a molecule called NAD to convert ethanol into something called acetyl aldehyde. Acetyl aldehyde is particularly bad, it will kill cells and damage them indiscriminately. The body then uses another component of NAD to convert acetyl aldehyde into something called acetate, which can be used as fuel by the body.
This conversion process happens within the liver, but it’s important to note that if the body can’t do this conversion fast enough, acetyl aldehyde will build up in the body and cause more damage.
Additionally, the state of being tipsy or drunk is actually a poison-induced disruption in the way that neural circuits work. The effects vary from person to person and regular drinkers tend to feel more energized and good for longer periods of time, as opposed to occasional drinkers who feel good for a shorter period of time before transitioning into a state of tiredness or losing motor skills.
Long-Lasting Effects & Impulsivity, Neuroplasticity & Reversibility
Huberman discusses the effects of alcohol on the brain and behavior. He explains that when people drink, their prefrontal cortex and top-down inhibition is diminished. This leads to an increase in habitual and impulsive behavior. He also notes that the more often people drink, the greater the changes in the neural circuits that control habitual and impulsive behavior. These changes make it easier for people to behave impulsively and habitually, even when they are not drinking.
Huberman also delves into the cellular mechanisms behind these changes. He explains that chronic drinking increases the number of synapses in the neural circuits that control habitual behavior, leading to “a growth of the neural circuits in your brain that lead to existing habit execution.” On the other hand, chronic drinking reduces the number of synapses in the neural circuits that control behavior.
The good news is that these changes are reversible. According to Huberman, a period of abstinence of anywhere from two to six months can return neural circuits to normal. However, for people who have been drinking heavily for many years, the impact on the brain may be long-lasting. Huberman emphasizes that even in these cases, it is still important to focus on one’s health and the possibility of recovery.
Predisposition for Alcoholism; Chronic Consumption, Cortisol & Stress
When people consume alcohol, there is an initial shutting down of prefrontal cortical circuits and a gradual shutting down of memory control circuits. However, individuals can be divided into two categories; those who start to feel sedated after a couple of drinks, and those who do not. This can be a predictor of whether or not an individual has a predisposition for alcoholism.
Alcohol also affects the relationship between the hypothalamus, pituitary gland, and adrenals, which are responsible for regulating physiological balance and perceived stress levels. Regular alcohol consumption, even at moderate levels, such as one or two drinks per night, can lead to changes in the hypothalamic-pituitary-adrenal axis, resulting in increased cortisol release at baseline when an individual is not drinking. This can lead to an overall increase in stress and anxiety levels when an individual is not consuming alcohol.It is important to note that this effect is not often talked about, as the immediate effects of alcohol, such as reducing stress, are more commonly discussed. However, it is important to consider the long-term effects of chronic alcohol consumption on stress and cortisol levels.
Gut-Liver-Brain Axis: Alcohol, Gut Microbiome, Inflammation & Leaky Gut
Despite some of the documented positive effects of alcohol, the negative impacts are significant and worthy of attention. For those who enjoy alcohol, it is important to be aware of the consequences of consuming it in a chronic pattern.
One of the more serious effects to consider is the impact on the gut-liver-brain axis. The gut-liver-brain axis is a complex communication network between the gut, liver, and brain. The gut and brain communicate through nerve cells and chemical signaling, while the gut also communicates with the liver through neural and chemical signaling. The liver is the first site where alcohol is broken down and metabolized, and it also communicates with the brain.
When someone ingests alcohol, it disrupts the gut microbiome, which is the trillions of microbacteria that live in the gut and support the immune system. These microbacteria also regulate mood by releasing chemicals like serotonin and dopamine. Unfortunately, alcohol has a detrimental effect on these helpful microorganisms. It should come as no surprise that alcohol is a sterilizing agent, and it has been used for centuries to clean wounds. However, it is not recommended for cleaning wounds due to its harshness.
Alcohol & Brain Thickness
Alcohol consumption, even in light to moderate amounts, has been shown to reduce brain thickness. This is a well-documented fact supported by numerous studies. These studies have found that the amount of alcohol consumed is directly proportional to the reduction in brain thickness.
One such study found that there is a dose-dependent increase in shrinkage of gray matter volume and white matter tracks, which are the wires that connect different neurons, as a function of the amount of alcohol consumed. This recent study reinforces the conclusion that the best amount of alcohol to consume is none at all.
Alcohol & Cancer Risk: DNA Methylation, Breast Cancer Risk
Alcohol consumption has been linked to an increased risk of cancer, and one of the well-documented effects is its ability to alter DNA methylation and gene expression. This can lead to an increase in cancer risk in many tissues, but breast tissue is particularly vulnerable, particularly in women. Studies have shown that there is a proposed 4-13% increase in risk of breast cancer when people drink 10 grams of alcohol per day.
It’s important to note that the amount of alcohol in different drinks varies across the world. In Japan, one beer, glass of wine, or shot of liquor contains 7-8 grams of alcohol. In the US, one beer, glass of wine, or shot of liquor contains 10-12 grams of alcohol. And in Russia, one drink contains as much as 24 grams of alcohol.
This means, for people drinking 10 grams of alcohol per day, which is equivalent to one beer in the US, slightly more than one beer in Japan, or a third of a drink in Russia, there is a 4-13% increase in risk of cancer. This may seem alarming, but it’s important to remember that alcohol is a toxin that many people enjoy consuming. Despite this risk, people continue to consume alcohol, and in the US, prohibition has been attempted in the past but ultimately failed due to the high demand for the substance.
It’s also important to note that cancer is a result of dysregulation in cell cycles, and alcohol consumption can cause mutations that lead to this dysregulation. Some of these mutations are starting to be understood, such as the PD-1 pathway, but more research is needed to fully understand the link between alcohol consumption and cancer.
Alcohol & Pregnancy, Fetal Alcohol Syndrome
Fetal alcohol syndrome is a severe condition that affects the development of the fetus, leading to permanent damage to the brain, limbs, and organs such as the heart and lungs. Ingesting alcohol during pregnancy is not safe and should be avoided at all costs.
Despite this, there are still myths circulating that certain types of alcohol, such as champagne, are safe to consume during pregnancy. This is categorically false. Alcohol is a toxin, and all types of alcohol can harm a developing fetus. The reason fetal alcohol syndrome exists is because alcohol disrupts cellular processes, including the orchestrated development of the embryo from conception to birth.
As a neurobiologist and embryology professor, he explains that embryonic development is controlled and precise, with checkpoints and recovery mechanisms in place to ensure the growth of a healthy fetus. However, alcohol acts as a mutagen, altering DNA and disrupting these checkpoints, making it one of the worst substances a developing fetus can be exposed to.
It’s important to note that fetal alcohol syndrome manifests on a continuum, and some changes may be more minor than others. Thankfully, the brain of young children is incredibly plastic, and there are things that can be done to help recover neural circuits that did not develop well. However, it’s important to emphasize that there is zero evidence that certain forms of alcohol are safer for pregnant women to ingest than others.
Hormones: Testosterone & Estrogen Balance
The literature on this subject is extensive, and there are many different hormones that are affected by alcohol consumption. However, the hormones that are most often discussed are testosterone and estrogen.
Testosterone and estrogen are present in both men and women and play important roles in things like libido, sexual development, and cognitive function. However, alcohol, specifically the toxic byproducts of alcohol, can increase the conversion of testosterone to estrogen. This occurs in a number of different tissues and can have negative effects on both men and women.
In women, this increase in the conversion of testosterone to estrogen can lead to an increased risk of estrogen-related cancers, such as breast cancer. In men, it can lead to growth of breast tissue, decreased sex drive, increased fat storage, and other negative effects.
It’s also worth noting that the effects of alcohol on hormone levels can vary depending on the amount consumed. Small amounts of alcohol may temporarily increase levels of testosterone, but chronic alcohol consumption can lead to decreased levels of testosterone over time. It is fair to say, based on the literature, that regular alcohol consumption is likely to disrupt hormone levels and can have negative effects on both men and women.
Alcohol & Serotonin, SSRIs & Depression, Risk for Alcoholism, Blackouts
Huberman discusses the neurochemical effects of alcohol on the brain and its relation to serotonin. He explains that alcohol consumption affects the activity of neurons that control the release of serotonin, which is a neuromodulator that changes the activity of neural circuits and is involved in mood and feelings of well-being. He mentions a recent study that has generated interest in serotonin and its relation to depression and how selective serotonin reuptake inhibitors (SSRIs), such as Prozac, can help alleviate depression by changing neural circuits rather than increasing serotonin itself. He emphasizes that it’s important to talk to a doctor before taking SSRIs and that they can be a valuable treatment in conditions such as OCD.
He then proceeds to talk about how alcohol consumption and specifically the conversion of alcohol into acetyl aldehyde disrupts the mood circuitries in the brain, making them hyperactive at first, which is why people become talkative and feel good after a few sips of alcohol. However, this effect decreases with time and high doses of alcohol can lead to depression-like symptoms. He also warns about the risk of blackouts, which occur when alcohol disrupts the hippocampus and its ability to transfer memories from short-term to long-term storage. He also talks about the risk of alcoholism, which is an addiction to alcohol and how it is related to the disruption of these mood circuitries and the reward system in the brain.
Negative Effects of Alcohol Consumption
First and foremost, it is important to understand that alcohol is a toxin to the cells of the body. Some people argue that consuming a toxin in small amounts can be beneficial, through a process known as hormesis. However, the evidence suggests that this does not apply to alcohol. Drinking alcohol in small amounts may not have immediate negative effects, but it can still cause damage to cells in the long run.
According to Huberman, the center of mass of the literature on alcohol suggests that no consumption, zero consumption, is better for health than low to moderate consumption. In other words, the less alcohol you drink, the better it is for your health. He also notes that consuming alcohol can have negative effects on the gut microbiome and the stress system.
So what can we do to offset the negative effects of alcohol consumption? Huberman suggests acquiring tools and getting proficiency with behavioral techniques that can help with stress modulation, without involving alcohol consumption. These tools and protocols can be beneficial for health in any case, regardless of whether or not you choose to consume alcohol.
It’s also important to note that Huberman is not here to tell you what to do or not do. He’s simply presenting the facts about the negative effects of alcohol consumption and offering suggestions for how to offset those effects. The choice is ultimately up to the individual.
Hangover: Alcohol & Sleep, Anxiety, Headache
Hangovers are a common experience for many people who consume alcohol. They are a constellation of effects such as headaches, nausea, and anxiety. Huberman explains that the anxiety associated with hangovers is likely due to the effect of alcohol on cortisol levels. He advises that anyone experiencing this type of post-alcohol consumption anxiety should refer to the Huberman Lab podcast episode on stress and anxiety, where they can find tools to deal with anxiety, including behavioral and nutritional supplement-based options.
Hangovers are also associated with other symptoms such as stomachaches, feelings of malaise, and fogginess. These symptoms can be related to the impact of alcohol on sleep. Alcohol disrupts the architecture of sleep, and can prevent the brain from getting the restorative deep sleep it needs. This is why people often wake up feeling groggy and unrefreshed after a night of drinking.
Huberman Lab Podcast has a episode on sleep with Dr. Matthew Walker from UC Berkeley, a world-expert in sleep and the author of the book Why We Sleep. Dr. Walker told Huberman that when alcohol is present in the brain and bloodstream, the architecture of sleep is disrupted, preventing the brain from getting the slow-wave sleep, deep sleep, and rapid eye movement sleep, which are all essential for getting a restorative night’s sleep.
Additionally, alcohol can also disrupt the gut microbiome, by destroying good, healthy gut microbiota, which leads to leaky gut. There is also some evidence that alcohol may disrupt the gut microbiome’s ability to produce neurotransmitters and hormones such as serotonin and melatonin. All these factors contribute to the unpleasant symptoms of a hangover.
Types of Alcohol & Hangover Severity, Congeners
Studies have shown that different types of alcohol lead to varying levels of hangover severity. At the lower end of the scale is beer, while whiskey is more likely to cause a hangover than gin. On the other hand, rum and red wine are more likely to cause a hangover than other types of alcohol. At the top of the list of drinks that induce hangovers is brandy.
There is a legend that drinks with a high sugar content lead to greater hangovers, however, studies have shown that this is not the case. For example, ethanol diluted in orange juice is at the bottom of the list of drinks that induce hangovers, while brandy is at the top of the list.
What sets these drinks apart is the levels of congeners they contain, these are substances such as nitrites that give alcohol its distinctive flavor, but also lead to some of the inebriating effects of alcohol. Congeners are found in greater quantities in darker-colored drinks such as brandy, and are responsible for disrupting the gut microbiome, leading to the symptoms of hangover.
Huberman suggests that having a healthy gut microbiome and perhaps ensuring that you bolster your gut microbiome the day after drinking can be especially important for warding off hangover or at least reducing the effects of hangover. It’s also interesting to see a study on this by giving some people probiotics, prebiotics, and low sugar fermented foods and see what the effects are in terms of subjective effects of hangovers.
Are There Any Positive Effects of Alcohol?, Resveratrol
You may have heard that there are positive effects of alcohol consumption, particularly in red wine, which is enriched in resveratrol. However, the truth is that if indeed resveratrol is good for us, the amount of red wine that one would have to drink in order to get enough resveratrol in order for it to be health-promoting is so high that it would surely induce other negative effects that would offset the positive effects of resveratrol.
Low to moderate consumption of red wine, one to four glasses per week, may have some positive effects on stress reduction, but it is important to note that the research in this area is not well-established.
Drinking red wine for the sake of resveratrol is not a good argument as the amounts required to have positive effects would also have negative consequences. Huberman acknowledges that it is not his intention to discourage people from drinking red wine but wants to ensure that the information is accurate and that people are aware of the actual science behind it.
Alcohol has been consumed by humans for thousands of years, and has been used for various purposes such as nutrition and medicine. However, it also has negative effects on the body, specifically on the brain.
A recent study has shown that even low to moderate levels of alcohol consumption, such as one or two drinks per day, can lead to degeneration of neurons in the brain. Additionally, alcohol is metabolized into toxic molecules that can cause damage to cells and organs in the body.
Genetic predisposition for alcoholism is influenced by a combination of genes and environmental factors such as patterns of abuse, social pressures, and trauma. Consuming alcohol at a young age also increases the risk of developing an alcohol use disorder.
The negative effects of alcohol on the body are significant, specifically the impact on the gut-liver-brain axis, which can disrupt the gut microbiome, leading to inflammation and leaky gut.
The alcohol also has a detrimental effect on brain thickness and increases cancer risk in many tissues, particularly in breast tissue.
It’s crucial for individuals to be aware of the risks associated with excessive or chronic alcohol consumption, and for those who enjoys alcohol it’s important to consume it in moderation.
Articles Associations between alcohol consumption and gray and white matter volumes in the UK Biobank: https://go.nature.com/3PNFj7y
Gut Microbiota at the Intersection of Alcohol, Brain, and the Liver: https://bit.ly/3AaeF2F
Tolerance to alcohol: A critical yet understudied factor in alcohol addiction: https://bit.ly/3CmfCYo
Associations Between Drinking and Cortical Thickness in Younger Adult Drinkers: Findings From the Human Connectome Project: https://bit.ly/3AeUosJ
Moderate Alcohol Consumption and the Risk of Breast Cancer: https://bit.ly/3PHlJcK
Can alcohol promote aromatization of androgens to estrogens? A review: https://bit.ly/3dJjGHZ
Other Resources Examine – Alcohol & Hangover: https://bit.ly/3QHYpx4
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