Home / The Physical & Psychological Effects of Alcohol / Causes of Slurred Speech from Drinking Alcohol

Alcohol causes a lot of changes to the body and brain. Immediate effects include feeling more relaxed, sleepy, and talkative or social. After a couple of drinks, reflexes, perception, and reaction time will slow down, making tasks like driving dangerous. At very high levels of drunkenness, slow brain activity can lead to dizziness, double vision, vomiting, slow breathing, falling, memory loss, and passing out.

Slurred speech is a stereotypical sign of being drunk, so much so that doctors and police officers use this symptom as an indication that a person is very drunk. Consistently slurred speech may also be a sign that someone struggles with chronic alcohol abuse and may have brain damage causing this condition.

Short-Term Speech Slurring Indicates Drunkenness

Essentially, alcohol enters the bloodstream and is sent all over the body, including to the brain. All areas of the brain will be affected by the presence of alcohol, but some of these effects will be more apparent than others. More immediate changes after a couple of drinks include stumbling and forgetting words. If you are out having a few social drinks with friends or coworkers, and someone in the group starts slurring their speech, it is a sign they should stop drinking. This sign typically doesn’t begin until blood alcohol concentration (BAC) reaches 0.1%, which is over the legal driving limit of 0.08%. But why does their speech get sloppier? The temporary effect of too much alcohol is caused by the toxin’s interaction on neurons in the brain, mainly in the cerebellum.

First, alcohol changes how much gamma-aminobutyric acid (GABA) the brain produces. When the brain does not have enough GABA, which occurs with anxiety disorders or epilepsy, neurons fire too fast; when there is more GABA present, neurons fire slower. Too much GABA and the brain does not process information from the body very well, leading to slower movements, changes in time perception, and slurred speech. Alcohol also suppresses the production of glutamate, a neurotransmitter that stimulates excitement and energy; this suppression enhances the slowing, sedating effects in the brain.

A 2015 study examined specific neurons called Purkinje neurons, which are involved in motor coordination and muscle memory. Located in the cerebellum, these neurons help to coordinate voluntary muscles and transfer repeated motions into long-term memory. For example, a person learning to play the violin will use Purkinje neurons to eventually remember chords. Alcohol disrupts these neurons’ firing. At a BAC of 0.05% to 0.08%, this disruption shows up in slower physical reaction times, especially while driving, which is a behavior learned through voluntary muscles. Increased BAC leads to further disruption, changing other voluntary muscle coordination, including use of the tongue.

Two additional areas of the brain are involved in speech production and affected by alcohol. The supplementary motor area is associated with creating sentences, and Broca’s area controls language processing. These areas can be affected very differently due to individual differences, including gender, weight, age, and alcohol tolerance. People who have higher language processing ability may also experience less slurring because these areas of their brain process more effectively.

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Long-Term Speech Changes Mean Chronic Health Problems

People who drink excessively for a long time put themselves at risk for several chronic health problems, and brain damage is one of those problems. In the medical world, difficulty saying words is called dysarthria. This change in speech can be caused by several medical conditions, including:

  • Brain injury
  • Brain tumor
  • Multiple sclerosis
  • Parkinson’s disease
  • Stroke
  • Dementia
  • Other degenerative brain diseases
  • Head injury
  • Damage to the nerves of the jaw or neck

Acute alcohol intoxication or being drunk is a temporary cause of dysarthria, but over time, alcohol abuse can damage the brain and may make this condition permanent. Signs of dysarthria include:

  • Mumbling
  • Speaking softly or in a whisper
  • Having a nasal sound to the voice
  • Strained, hoarse, or breathy voice

If a person develops these symptoms and they do not clear up, it could be an indication of some form of brain damage, including deterioration from alcohol abuse.

Alcoholic dementia and neuropathy are two conditions that contribute to dysarthria from chronic alcohol abuse. Neuropathy is nerve damage, which may become permanent; when it is caused by alcohol abuse, nerve damage is due to vitamin deficiency. It may include symptoms like:

  • Numbness
  • Tingling
  • Physical weakness
  • Movement problems

This nerve damage may most clearly affect the hands, feet, arms, or legs, but it could cause muscle twinges or sagging in the face, or nerve damage in the jaw, which can change how a person speaks.

Alcohol abuse also increases the risk of cancers in the mouth or throat. A tumor in these areas may affect speech and voice quality, causing dysarthria.

Get Help to Avoid Harm from Alcohol Abuse

Ending alcohol abuse is extremely important to avoid long-term damage. If a loved one consistently slurs their words or begins to forget common words, this may be an indication that they drink too much. They may be consistently intoxicated, and that can lead to chronic health problems, many of which also manifest as speech changes.