Why can’t an alcoholic have one drink? This question baffles not only the alcoholic (now diagnosed as a person with severe alcohol use disorder) but their family members and close friends, as well.

The answer is in the details that explain the brain disease of addiction (aka brain disorder) – whether it’s an addiction to alcohol (aka alcoholism) [or other drugs (drug addiction), for that matter].

[But before I continue, there’s been a great deal of research and advanced understandings about the terms, alcoholism, which is now diagnosed as a severe alcohol use disorder, and alcoholic and alcohol abuse. This article provides clarification. For the purposes of this article, I’ll use the terms the general population still uses – alcoholic, alcohol abuse and alcoholism.]

Brief Explanation of the Disease of Alcoholism

Alcoholism is one of the brain diseases (disorders) of addiction. How? By its simplest definition, disease is something that changes cells in a negative way. When cells are negatively changed in a body organ, it changes the health and function of that body organ.

Cancer cells in the lungs, for example, change the health and function of the lungs, causing lung cancer. Alcoholism changes cells in the brain, which in turn changes the health and function of the brain, resulting in this brain disease, aka brain disorder.

This brain disease develops, and its development starts with a person abusing alcohol (or other drugs).

Why is it an alcoholic cannot have just one drink? The answer is in the details that explain the brain disease of addiction.

Alcoholism Starts with Excessive Ethyl Alcohol Chemicals Changing the Brain’s Communication System.

Abusing alcohol means a person drinks more than their liver can metabolize, and its through that metabolizing that the body rids the ethyl alcohol chemicals in alcoholic beverages. This post explains how the body processes alcohol.

This excess of ethyl alcohol – waiting its turn out the liver – interrupts the brain’s normal cell-to-cell communication system. This communication system is also referred to as an electro-chemical signaling process, neural networks, neural circuitry and neural connections.

My post, Here’s to Neural Networks! explains the key components of this system: neurons, branchlike extensions, neurotransmitters, receptors and synapses. The neuron is the “electrical signaling” part and the “neurotransmitters/receptors” are the chemical part. It takes both, along with branchlike extensions and synapses, to make cell-to-cell communication possible.

These cell-to-cell communication components work together to allow the brain do what it does — control everything a person thinks, feels, says and does.

All of which ties together to explain…

Why an Alcoholic Can’t Have One Drink

As I stated above, alcoholic beverages contain ethyl alcohol chemicals. These chemicals reach the brain through the bloodstream and may act on neurotransmitters, trigger a signaling (a message) or fool receptors, allowing the ethyl alcohol chemicals to activate a neuron or exaggerate a neuron’s normal messaging. In other words, they change the brain’s normal cell-to-cell communications by interacting with the chemical portions of the neural network – neurotransmitters and receptors.

SPECT showing brain changes caused by heavy week-end use.

Anyone who drinks or uses alcohol will experience some version of this because ethyl alcohol chemicals allow dopamine reliant pleasure/reward neural networks to function. These are the ones that give a person a pleasurable feeling for drinking an alcoholic beverage.

But if a person abuses alcohol, they chemically and structurally change their brain, making their brain more vulnerable to the five key risk factors for developing alcoholism (or other drug addictions).  The more risk factors, the more likely their brain will “cross the line” from alcohol abuse to alcohol dependence (aka alcoholism).

Why One Drink Can Cause a Relapse for an Alcoholic

The answer for this one has to do with brain mapping. When person activates a series of neural networks over and over, the brain “maps” that series. The expression for this is “neurons that fire together wire together” to create “embedded brain maps.”

Brain maps are what allow us to get through the day with efficiency. If we had to think through all the body parts that go into brushing our teeth, for example, this one activity would take quite some time to complete. With an embedded brain map, it takes on a “life of its own,” so to speak. It just happens. It’s become a habit.

These maps are triggered by cues — sound, sight, touch, smell, emotions… — and they can take hold (activate) within milliseconds. One analogy I use is the light switch. When the switch is off, the lamp is off; there is no light. But when the switch is flipped, before a person can blink their eyes, the electricity has reached the lamp, and it lights. Brain maps can activate that fast!

If a person’s brain is injured – by a traumatic brain injury or PTSD or substance abuse or alcoholism, as examples – wherever the injury or change occurs will be the neural networks impacted. Meaning – a person’s behaviors governed by brain maps in that area of the brain will change.

For someone with alcoholism, their brain has mapped a complex series of embedded brain maps that involve alcohol abuse, risk factors (genetics, early use, mental illness, social environment, childhood trauma), the characteristics of this brain disease (tolerance, loss of control, physical dependence and cravings) and triggers/cues (stress, relationships, anger, fear, good day, bad day, anxiety, work…). These maps will always be there until that person stops the use of alcohol, which in turn stops the ethyl alcohol chemicals changing neural connections, AND treats their brain disease.

If they drink, again, they will activate those old, embedded brain maps and find themselves in relapse.

For more information…

Check out:

• NIDA’s Drugs, Brains & Behaviors: the Science of Addiction (alcohol is considered a drug)
• NIDA’s Principles of Effective Treatment
• My latest book, 10th Anniversary Edition If You Loved Me, You’d Stop! (the first half explains how a person develops alcoholism and what it takes to effectively treat it).

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Note: this post was first published on December 30, 2013. It was updated November 2021.

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Lisa Frederiksen

Author | Speaker | Consultant | Founder at BreakingTheCycles.com

Lisa Frederiksen is the author of hundreds of articles and 12 books, including her latest, "10th Anniversary Edition If You Loved Me, You'd Stop! What you really need to know when your loved one drinks too much,” and "Loved One In Treatment? Now What!” She is a national keynote speaker with over 30 years speaking experience, consultant and founder of BreakingTheCycles.com. Lisa has spent the last 19+ years studying and simplifying breakthrough research on the brain, substance use and other mental health disorders, secondhand drinking, toxic stress, trauma/ACEs and related topics.

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