Alcohol Tolerance Levels

You can drink enough alcohol for a period of time that you can develop a tolerance to some of its effects. If you drink long enough, you may find that drinking the same amount you usually drink does not produce the same effect.

In other words, if you have developed alcohol tolerance you have to drink increasingly greater amounts of alcohol to feel the same effects you used to feel with fewer drinks.

You may think that not having alcohol interfere with your behaviour and ability to function like it used to do is a positive occurrence, however, the development of tolerance to alcohol can actually signal pending problems.

Tolerance to the effects of alcohol can influence drinking behaviour and consequences in many ways.

Alcohol Tolerance Can:

  • Encourage greater alcohol consumption
  • Contribute to alcohol dependence
  • Cause organ damage
  • Affect the performance of tasks
  • Contribute to the ineffectiveness of medications
  • Increase the toxicity of other drugs
  • Contribute to the risk of alcoholism

There are several ways that tolerance to alcohol develops:

Functional Tolerance

Functional tolerance is when the brain functions of drinkers adapt to compensate for the disruption that alcohol causes in their behaviour and their bodily functions.

Have you ever known someone who could consume large amounts of alcohol and not display any obvious signs of intoxication? That is because that person has developed a functional tolerance to alcohol.

When someone has had enough to drink that they should be exhibiting some signs of behavioural impairment and they do not, their tolerance to alcohol is allowing them to drink increasing amounts of alcohol.

Functional Tolerance Can Result in Dependence

The problem is that a higher level of consumption can result in developing a physical dependence on alcohol and developing alcohol-related organ damage.

Research has found, however, that functional tolerance can develop at the same rate for all of the effects of alcohol. For example, someone may quickly develop a functional tolerance for mental functions, such as solving puzzles, but not for tasks requiring eye-hand coordination, such as driving a vehicle.

Alcohol Abuse vs. Dependence

Different Types of Functional Tolerance

Sometimes drinkers will quickly develop a tolerance to the unpleasant effects of intoxication, such as becoming nauseous or dizzy, while not developing a tolerance to the pleasurable effects. This can cause increased alcohol consumption.

There are different types of functional tolerance to alcohol which are produced by different factors and influences.

Acute Tolerance

When a drinker develops a tolerance to the effects of alcohol during a single drinking session, it is called acute tolerance. The drinker may appear to be more intoxicated in the early stages of the drinking session than near the end.

But, acute tolerance typically develops to the “feeling” of intoxication, but not to all of the effects of alcohol. Consequently, the person may be prompted to drink more, which can impair those bodily functions that do not develop acute tolerance.

Environment-Dependent Tolerance

Research has found that alcohol tolerance can be accelerated if drinking over a series of drinking sessions always take place in the same environment or accompanied by the same cues.

Studies have found that when drinkers consumed their alcohol in the same room all the time their heart rate increased to a lesser extent than when they drank in a new environment.

Cues Associated With Drinking

Another study found that “social drinkers” who were given an eye-hand coordination task, performed better if they consumed their alcohol in a bar-like environment, rather than an office environment.

The researchers concluded that the subjects were more alcohol tolerant in the bar environment because it contained cues associated with drinking. This is called environment-dependent tolerance.

The Dangers of Drinking and Driving

Learned Tolerance

Alcohol tolerance can also be accelerated by practising a task while under the influence of alcohol. Even if the subjects only mentally rehearsed the task after drinking alcohol, they developed the same level of tolerance as those who actually physically practised the task while drinking.

This is called behaviorally augmented tolerance or learned tolerance.

Rewards Can Affect Tolerance

Learned tolerance can also be accelerated by the expectation of a reward. One study found that subjects who knew they would receive money for the successful performance of a task while under the influence developed tolerance more quickly than when they did not expect a reward.

How Does This Apply to Real-Life Situations?

Repeatedly driving the same route home while intoxicated could cause the driver to develop a tolerance for the task and reduce alcohol-induced impairment. However, that tolerance for that specific task is not transferable to a new task.

For example, if the driver encountered unexpected situations, a detour, or a change in driving conditions, he could lose any previously acquired tolerance to alcohol’s impairment of his driving skills.

Environment-Independent Tolerance

Functional tolerance to alcohol can develop independently of environmental influences with exposure to large quantities of alcohol. Using significant higher amounts of alcohol, researchers found that laboratory animals developed tolerance in an environment different from the one in which they were given alcohol.

This is called environment-independent tolerance.

Metabolic Tolerance

Metabolic tolerance occurs when a specific group of liver enzymes is activated after a period of chronic drinking and results in more rapid elimination of alcohol from the body.

This activation of the liver enzymes increases the degradation of alcohol and reduces the time during which alcohol is active in the system and consequently reduces the length of intoxication.

Metabolic Tolerance Can Lead to Liver Damage

When chronic drinking activates these enzymes, however, it can cause health problems for the chronic drinker because it can also affect the metabolism of other drugs and medications, producing possible harmful effects, including liver damage.

Studies have also found that metabolic tolerance can also lead to the ineffectiveness of some medications in chronic drinkers and even in recovering alcoholics.

How Alcohol Damages the Liver

Tolerance and the Predisposition to Alcoholism

Research has revealed that some aspects of alcohol tolerance are genetic. Several studies comparing sons of alcoholics fathers to sons of nonalcoholic fathers found tolerance differences that could affect drinking behaviour.

Some studies found that sons of alcoholic fathers were less impaired by alcohol than the sons of nonalcoholic fathers.

Other studies found that sons of alcoholic fathers displayed acute tolerance for alcohol – experiencing the pleasurable effects of alcohol early in drinking sessions, while not experiencing the impairing effects of alcohol later in the sessions.

The genetic predisposition to alcohol tolerance could contribute to increased alcohol consumption and the risk for alcoholism in the sons of alcoholic fathers.

Is Alcoholism Genetic?

Developing a tolerance for alcohol’s effects quickly could be a clue that the drinker is at risk of developing alcohol-related problems whether they are a son of an alcoholic or not.

If you know someone who reportedly can “hold their liquor well” or who drinks large amounts of alcohol without exhibiting outward signs of intoxication, there is a chance that person is at risk for developing medical complications from alcohol use, as well as developing alcohol use disorders.


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