TOLERANCE TO DRUGS AND ALCOHOL: WHAT IT CONSISTS OF AND TYPES - ARTE - 2025

The drug tolerance occurs when a drug is consumed continuously, resulting in a reduction of their effects on the body. In this way, it is necessary to increase the dose of the substance to feel its effects again.

Not all substances produce tolerance; it depends on the chemical composition of drugs and the brain's ability to differentiate them from its own neurotransmitters. For example, alcohol, illegal drugs, drugs such as benzodiazepines, or substances such as caffeine can cause tolerance.

Tolerance is part of a compensatory mechanism that the brain develops. When the drug begins to exert its effects in the body, the brain detects the existence of an alteration in its balance or homeostasis.

The main response of the brain to this threat to its normal functioning is to resist. To do this, it adapts the receptors and cellular mechanisms to the drug so that it does not take effect.

Ultimately, the brain's receptors become insensitive to the addictive substance. Thus, the person needs to consume a larger dose to feel its effects again.

If the person has used drugs regularly enough to experience tolerance, they will suffer withdrawal syndrome when they stop taking the substance.

Differences between tolerance and dependence

When a person repeatedly abuses drugs such as alcohol, hashish, cocaine, heroin, or others, they can develop both dependency and tolerance over time.

Tolerance and dependence are signs that sporadic use of a drug is beginning to be problematic. However, there are important differences between dependency and tolerance.

Tolerance

Tolerance develops when a person does not experience the same effects using the same amount of a certain drug or substance. Specifically, what happens is that the brain has adapted to the presence of the drug. Therefore, when a person has a high tolerance, she needs to take more frequent doses and in greater quantity than her friends.

Another sign is that they can begin to mix different substances to achieve the desired intoxication. For example, someone who has developed a tolerance to alcohol will not feel as drunk as before by drinking the amount they used to drink.

Thus, you will begin to drink more quickly or consume more alcoholic beverages. Or, choose strong liquors with a high alcohol content.

What it is doing is that the brain continues to adapt to these amounts of alcohol and ends up getting used to it, needing more and more alcohol to feel intoxicated.

Dependence

On the other hand, drug dependence appears when the individual feels that he cannot have a normal life without consuming certain substances. In this way, you need to take this drug to function well in your day to day.

If you don't take it, you will feel the uncomfortable and annoying withdrawal symptoms. Withdrawal symptoms are usually the opposite of those caused by the drug.

Another sign of drug dependence is that a person may spend a lot of time using it, looking for it, or thinking about it. It is possible that dependence is accompanied by tolerance when use is spread over time.

As the substance is abused, brain cells become more dependent on the effects of the drug. Little by little, they need this substance to maintain a balance in the functioning of the brain. This ends up producing structural damage that leaves cells unable to function properly without the drug.

Generation of addiction

Finally, a vicious cycle occurs, as tolerance grows, the dose increases, and damage to brain cells is becoming more serious.

On the other hand, if we talk about other substances such as certain medications, it may be that there is tolerance, but not addiction. For example, tolerance can develop to some effects of drugs prescribed to suppress pain without addiction to them.

Tolerance types

Tolerance affects receptors and brain cells, although there are other forms of tolerance as well. According to California State University-Fullerton, there are 3 mechanisms that contribute to increased tolerance (in addition to brain tolerance):

Metabolic tolerance

It refers to substances or drugs that are consumed orally. It is related to the speed with which the liver breaks down these substances. When the use is very continuous, this speed increases, with the drug remaining in the bloodstream for less and less time.

Behavioral tolerance

It is about the emotional response of the individual according to the expectations he has about the effects of the drug. That is, the person increases the dose voluntarily to obtain more intense effects.

Conditional tolerance

This mechanism increases tolerance through environmental cues. Apparently, certain environmental factors are associated with the desire to take the drug, such as activities, moods, certain places, situations or people.

These mechanisms, together with brain adaptation, feed off each other, resulting in increased tolerance to the drug.

According to the period of time

On the other hand Drug Abuse differentiates three types of tolerance according to the period of time:

- Acute or short-term: this tolerance arises from continued exposure to a substance for a relatively short period of time.

An example is what happens with cocaine. With the first dose, individuals experience euphoria, increased heart rate and blood pressure. However, with a second dose 40 minutes later, the positive effects of the drug do not increase as should be expected.

- Chronic: happens when the body adapts to constant exposure to the drug for weeks or months. The result is that the effects of the drug diminish, needing to take a higher dose than the previous one to experience the effects again with the same intensity.

- Learned: with exposure for years to certain substances, such as alcohol, the person may appear as if they have not ingested any substance. I mean, the drug no longer works. You can even successfully carry out activities of your daily life after consuming it.

Cross tolerance

Another type of tolerance, called cross tolerance, is also commonly talked about. In this one develops tolerance to a drug that at the same time extends to other similar substances. It tends to occur with those substances that exert similar effects on the brain.

Reverse tolerance

On the contrary, reverse tolerance is a state in which greater or equal effects are produced with a lower dose of the substance. It is very typical in chronic alcoholics. In some of these cases, they can get drunk with just a couple of drinks.

Can tolerance be reversed?

The brain is plastic. If you go long periods of time without using drugs, you will re-adapt your receptors and neurons to the new situation.

It must also be taken into account that most drugs or substances have more than one effect. Thus, tolerance tends to develop differently for each of them.

For example, heroin produces a very rapid tolerance to the effects of euphoria and well-being. Despite this, the effect of respiratory depression (reduction in the rate of respiration) remains unchanged. Therefore, it is possible to overdose or die.

The decrease in tolerance depends on the history of abuse of the substance. That is, if the drug has been taken for long periods before abstinence, it will take longer for the brain structures to return to their initial state.

However, in cases of chronic drug abuse, the level of damage to the body can be permanent, even if the substances are abandoned.

References

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