How does alcohol affect the brain?

Alcohol affects the brain in a variety of ways, including chemical processes, structure, and function. Here are some of the main ways in which alcohol affects the brain:

Central nervous system (CNS) depression

Central nervous system (CNS) depression is a condition in which the functioning of the central nervous system is slowed. Alcohol is a typical CNS depressant, which means that it suppresses the activity of the nervous system. This occurs by depressing neuronal function, primarily through an increase in the action of gamma-aminobutyric acid (GABA), the main inhibitory neurotransmitter in the CNS, and a decrease in the action of excitatory neurotransmitters such as glutamate. [1]

Under the influence of alcohol, the activity of brain centers responsible for coordinating movements, processing information, controlling emotions and making decisions is reduced. This leads to a number of changes in the body:

1. Response inhibition: Alcohol slows down the body's response to various stimuli. This can manifest itself in impaired coordination of movements, decreased reaction speed, and slower thought processes.
2. Decreased blood pressure and heart rate: Alcohol dilates blood vessels and lowers blood pressure, which can lead to feelings of relaxation and drowsiness. Heart rate may also slow down.
3. Muscle relaxation: Alcohol causes muscles to relax, which can lead to loss of control of movement and poor coordination.
4. Respiratory depression: High doses of alcohol can depress the respiratory center in the brain, causing slowed breathing and even respiratory arrest in extreme cases.
5. Drowsiness and depressed emotions: Alcohol can cause drowsiness, apathy, and depressed emotions, which can lead to changes in mood and behavior.

In general, alcohol has a depressive effect on the central nervous system, which can lead to a number of physiological and psychological changes. Although moderate alcohol use may not cause serious problems, excessive and/or chronic use can lead to a variety of health and social problems.

Effects on neurotransmitters

Alcohol affects a variety of neurotransmitters in the brain, which explains its diverse effects on behavior, mood, and overall body function. [2], [3] Below are the major neurotransmitters affected by alcohol:

1. Gamma-aminobutyric acid (GABA):

   • Alcohol increases the action of GABA, the main inhibitory neurotransmitter in the central nervous system. This leads to inhibition of neuronal activity and decreased brain excitability, which contributes to muscle relaxation, drowsiness and reduced anxiety. [4]

2. Noradrenaline and adrenaline:

   • Alcohol reduces levels of norepinephrine and adrenaline, neurotransmitters responsible for arousal and activation of the body. This can lead to a slower heart rate, decreased attention and reactions, and drowsiness. [5]

3. Dopamine:

   • Alcohol increases dopamine levels in the brain, which can cause feelings of pleasure and euphoria. This phenomenon plays a key role in the onset of alcohol dependence, as the body seeks to repeat the pleasurable sensations associated with drinking alcohol. [6]

4. Serotonin:

   • Some studies show that alcohol can increase serotonin levels in the brain. Serotonin is responsible for regulating mood, sleep, and appetite. Changes in serotonin levels can affect emotional state and overall well-being. [7], [8]

5. Glutamate:

   • Alcohol has an inhibitory effect on glutamate, the main excitatory neurotransmitter in the brain. This can lead to decreased brain activity, slower thought processes and impaired motor coordination. [9]

6. Endorphins:

   • Alcohol consumption can lead to the release of endorphins, natural opioid peptides that cause feelings of satisfaction and well-being. This can create feelings of euphoria and attachment to alcohol. [10]

Suppression of prefrontal cortex function

Alcohol has depressing effects on many parts of the brain, including the prefrontal cortex (PFC), which is a key part of the brain responsible for many higher cognitive functions and behavior regulation. [11], [12] Here's how alcohol affects prefrontal cortex function:

1. Cognitive decline: The prefrontal cortex plays an important role in problem solving, planning, decision making, controlling behavior, and performing purposeful actions. Alcohol use can lead to a decline in these cognitive functions because alcohol depresses the activity of the prefrontal cortex.
2. Reducing inhibition: The prefrontal cortex helps control inhibition, which is the ability to resist unwanted or inappropriate actions. With alcohol use, inhibition function can be impaired, leading to more risky or reckless behaviors.
3. Decreased attention and concentration: The prefrontal cortex also plays a role in maintaining attention and concentration. Under the influence of alcohol, a person may have difficulty concentrating on tasks and may become quickly distracted.
4. Decreased control over emotions: The prefrontal cortex helps regulate emotions and reactions to stressful situations. Alcohol use can weaken this control, leading to more emotional or maladaptive reactions to various stimuli.
5. Decreased ability to plan and organize: The prefrontal cortex is also involved in the processes of planning and organizing actions. Under the influence of alcohol, a person may have difficulty planning future actions and organizing tasks.

Deterioration of short-term and long-term memory

Alcohol can have negative effects on short-term and long-term memory. [13] Here's how it happens:

1. Short-term memory:

   • Alcohol affects the hippocampus, a key brain structure responsible for short-term memory. Under the influence of alcohol, the hippocampus may function less efficiently, resulting in difficulty remembering information for short periods of time.
   • People who drink large amounts of alcohol may experience "black holes" - temporary gaps in memory where they cannot remember what happened during the intoxicated state.

2. Long-term memory:

   • Long-term alcohol use can damage the hippocampus and other brain structures responsible for long-term memory. This can cause problems with forming new memories and retaining information over the long term.
   • Prolonged and excessive alcohol consumption can also lead to alcoholic amnesia, a condition in which a person loses the ability to recall events or information from the past, although their physical health may be generally normal.

3. Effects on cognitive function:

   • Alcohol intoxication can also decrease overall cognitive performance, which includes the ability to concentrate, pay attention, and problem solve. This can lead to difficulty performing cognitive tasks, including working with information from memory.

4. Memory retrieval deficits:

   • After a period of alcohol consumption, especially in large amounts, a person may experience a memory recovery deficit where they are unable to recall events that occurred while intoxicated.

Effects on neuronal plasticity

Neuronal plasticity is the ability of the nervous system to change its structure and function in response to experience, learning, and other stimuli. Alcohol can have a negative effect on neuronal plasticity, limiting it and promoting long-term changes in the brain. [14] Here's how alcohol affects neuronal plasticity:

1. Decreased synaptic plasticity:

   • Alcohol can impair synaptic plasticity, which is the ability of synapses (places of contact between neurons) to change their strength in transmitting signals. This can make it harder to learn and remember new information because synapses are less able to change.

2. Damage to dendrites:

   • Dendrites are the outgrowths of neurons through which they receive incoming signals from other neurons. Alcohol can damage the structure of dendrites, which affects their ability to transmit signals efficiently and participate in the formation of new connections between neurons.

3. Decreased formation of new neurons:

   • Some studies suggest that alcohol may inhibit the formation of new neurons in certain areas of the brain, such as the hippocampus, which plays a key role in learning and memory. This can limit the brain's ability to adapt and learn new information.

4. Effects on glial cells:

   • Glial cells play an important role in maintaining and protecting neurons. Alcohol can have a negative effect on glial cells, which can degrade the environment for neurons and lead to impaired neuronal plasticity.

5. Decreased regeneration of nerve tissue:

   • If nerve tissue is damaged, alcohol can slow or prevent its regeneration, which can worsen the effects of injury or other damaging factors.

Toxic effects of alcohol on the brain

Alcohol is a psychoactive substance that can have toxic effects on the brain, especially with prolonged and excessive use. [15] The following are the main ways in which alcohol can be toxic to the brain:

1. Neurotoxic effects: Alcohol is a neurotoxin, which means it can directly damage neurons and other brain cells. High concentrations of alcohol can cause neuronal degeneration and neuronal death, especially in vulnerable areas of the brain such as the hippocampus and cortex.
2. Inflammation and oxidative stress: Alcohol can trigger inflammatory processes in the brain and activate oxidative stress mechanisms, leading to cell and tissue damage. This can increase the risk of developing neurodegenerative diseases such as Alzheimer's disease.
3. Blood supply disorder: Alcohol use can cause blood vessels to constrict and disrupt the blood supply to the brain. This can lead to hypoxia (lack of oxygen) in certain areas of the brain, which can cause neuronal damage and death.
4. Increased blood vessel permeability: Alcohol can increase the permeability of blood vessels in the brain, allowing toxic substances and other harmful substances to enter brain tissue more easily. This can increase the effects of toxins on neurons and other brain cells.
5. Metabolic disruption: Alcohol can interfere with metabolic processes in the brain, including neurotransmitter synthesis, metabolism and mitochondrial function. This can lead to energy deficits and brain cell dysfunction.

Destruction of the protein structure of the brain

Alcohol can cause damage to the protein structure of the brain through several mechanisms: [16]

1. Oxidative stress: Alcohol consumption can stimulate oxidative stress processes in the brain. Oxidative stress occurs when free radicals are produced in the body that can damage proteins, lipids, and DNA in cells. In the brain, oxidative stress can lead to the breakdown of protein structure, including neuronal proteins, which can lead to impaired function.
2. Inflammation: Alcohol consumption can lead to inflammation in the brain. Inflammation is one of the body's defense mechanisms, but with prolonged and chronic inflammation, it can become negative and lead to damage to brain proteins and tissues.
3. Toxic Metabolites: Alcohol is metabolized in the body into various toxic metabolites such as acetaldehyde and free radicals, which can damage brain proteins and cause them to break down.
4. Cell membrane damage: Alcohol can damage cell membranes, causing toxic substances to enter and damage brain cells, including proteins.
5. Protein degradation: Some studies show that alcohol can stimulate the activation of enzymes that degrade proteins in the brain. This can lead to disruption of normal functioning of protein structures and damage to brain tissue.

Dehydration of the brain

Dehydration is the process of water loss from tissues and organs of the body. Alcohol can contribute to brain dehydration for several reasons: [17]

1. Diuretic action: Alcohol acts as a diuretic, which means that it helps increase the production of urine and the removal of excess fluid from the body by the kidneys. This can lead to dehydration of the body, including the brain.
2. Inhibition of antidiuretic hormone: Alcohol can inhibit the production of antidiuretic hormone (vasopressin), which regulates fluid levels in the body. Reduced secretion of this hormone can increase diuresis and lead to additional water loss from the body.
3. Reduced thirst: Drinking alcohol can reduce the sensation of thirst, which can lead to inadequate fluid intake. It can also contribute to dehydration of the body, including the brain.
4. Toxic effects on the hypothalamus: The hypothalamus is a part of the brain that regulates many functions, including fluid levels in the body. Alcohol can have a toxic effect on the hypothalamus, which can interfere with its ability to properly regulate water balance.

Brain dehydration can lead to a variety of negative effects, including decreased cognitive function, headaches, drowsiness, irritability, and decreased mood and overall well-being. It is important to remember that brain dehydration can be particularly dangerous, as the brain is very sensitive to water loss and can quickly begin to experience negative effects when there is a lack of fluid.

How does alcohol affect the blood vessels of the brain?

Alcohol has a variety of effects on the blood vessels of the brain:

1. Vasodilation: Alcohol consumption can cause blood vessels, including those in the brain, to dilate (vasodilate). This can temporarily increase blood flow and lead to a feeling of dizziness or "blood rushes" to the head.
2. Increased risk of brain strokes: In some cases, excessive alcohol consumption can increase the risk of stroke. This may be due to its ability to raise blood pressure and cholesterol levels, as well as an increased tendency to form blood clots.
3. Effect on blood flow: Alcohol consumption can change the overall blood flow, including blood flow in the brain. Depending on the dose, this can lead to increased or decreased blood flow in certain areas of the brain.
4. Toxic Effects: Chronic and/or excessive alcohol consumption can have toxic effects on brain blood vessels and cells, which can contribute to brain damage and degeneration.
5. Deterioration of cerebral circulation: Alcohol consumption can lead to deterioration of cerebral blood flow regulation and microcirculation in the brain, which can affect brain function and contribute to the development of various diseases such as vascular dementia or Alzheimer's disease.

Overall, while some studies suggest that moderate alcohol consumption (mainly red wine) may be associated with some heart and vascular health benefits, excessive and/or chronic alcohol consumption can have negative effects on brain blood vessels and overall health. [18]

Why do you feel sleepy after drinking alcohol?

After drinking alcohol, many people experience feelings of drowsiness and fatigue. This happens because of several factors:

1. Depressant effects on the nervous system: Alcohol is a nervous system depressant, which means it slows down brain activity. This can cause drowsiness and muscle relaxation.
2. Elevated GABA: Alcohol stimulates the release of the neurotransmitter gamma-aminobutyric acid (GABA), which is an inhibitor and can contribute to drowsiness and relaxation.
3. Increased melatonin: Alcohol consumption can also increase levels of melatonin, a hormone that regulates the sleep-wake cycle, which can also contribute to drowsiness.
4. Decreased sleep quality: While alcohol can help one fall asleep faster, it can also decrease sleep quality by causing more shallow and less restorative sleep. This can cause a person to wake up in the morning feeling tired and unrested.
5. Dehydration: Alcohol is a diuretic, which means it can increase the frequency of urination and cause dehydration of the body. It can also contribute to feelings of fatigue and drowsiness.

The effects of drowsiness after drinking alcohol can vary depending on the individual body and the amount of alcohol consumed. It is important to remember that alcohol consumption can affect the quality of sleep and overall health, so it is recommended to consume it in moderation and monitor your feelings and reactions to it.