Drug addiction, better known in psychology as tolerance, is defined as the state of adaptation of the organism to the drug.
When you start using any type of drug, we notice that small amounts produce big effects, changes and sensations in the person. It does not take large amounts for our behavior to be affected by the narcotic. But if we keep taking the same medicine or similar medicines we will notice that it does not produce the same effect it did at the beginning, usually it will be less, indicating that our body has become accustomed to the medicine.
In the next article we will define the term tolerance, so we will see that it is divided into different types; we will also know what changes are happening in our body when it gets used to it and we will see that the environment also influences the process of drug tolerance.
Read on if you want to know what changes your repeated use of a narcotic causes in your body, why the effect is reduced, or how to decrease the habit.
What is drug addiction?
Drug addiction, or also called tolerance, is defined as the state of adaptation of the body which decreases the response to the same amount of drug that previously produced a greater effect or the need for an increase in the dose of consumption to obtain the same effects as those obtained at the start. In other words, it is the decreasing effect of the drug by consuming it repeatedly.
Before we follow the specific case of drug addiction, let’s see how Psychology describes the term addiction.
Characteristics of habituation
Addiction, as a general concept in psychology, is explained as the decrease in the individual’s response to a repeatedly presented stimulus. It is a central process, that is, it occurs by modification of the central nervous system (CNS) and not by a state of fatigue of the individual or by sensory adaptation. The answer is innate, differentiating from extinction where yes learning has taken place.
Some of its properties are the specificity of the stimulus, it means that there will only be a decrease in the response to the particular stimulus which produced habituation and generalization, there will be habituation to the specific stimulus in different situations.
This process can lead to spontaneous healing, which means that, over time, the response to the habitually diminished stimulus increases again, returning to the initial state.
By understanding the process of addiction and more specifically drug addiction, we will see what kind of drug tolerance exists.
Types of drug addiction
In this section we will define the two types of drug addiction that exist, seeing how the body acts on the drug and how the substance generates changes in the body, more specifically in its receptors.
1. Pharmacokinetic or metabolic tolerance
This type of drug habit appears after repeated administration of the substance, a process that accelerates the degradation mechanisms of this drug.
In this particular case, the change occurs mainly in the substance, which has a faster decrease in concentration in the organism, caused by the acceleration of its degradation.
2. Pharmacodynamic, pharmacological, neural or functional tolerance
This variant of addiction occurs when, after repeated consumption of the substance, drug receptors get used to its presence, causing the body to adapt to the substance and therefore higher doses than initially required are needed.
Unlike other types of addiction, pharmacodynamic tolerance causes more changes in the body, because at the sites of drug reception in the brain there is an increase or decrease in the number and sensitivity to the substance . .
After discussing the two classes of tolerance, we will describe two terms more closely related to drug addiction.
We will refer to this process when the consumption of a particular substance not only results in addiction to it, but tolerance to other similar drugs will also be shown.
This would be the case, for example, in people with intolerance to alcohol, who will also show tolerance to tranquilizers, requiring higher doses to see the effect.
Reverse habituation occurs when, after consuming similar or even lower doses of the same drug, similar or better effects are obtained, thus presenting a result contrary to what one expects from habituation, hence the name of reverse tolerance.
This paradoxical process may be due to the accumulation of the drug in certain tissues of the body and its subsequent release, or hypersensitivity of the substance receptors. That is, an increase in the function or the number of receptors.
Given the effects associated with reverse tolerance, this it is linked to the appearance of an overdose, without it being necessary for the dose taken to be greater than that normally consumed.
Biological effects that addiction produces on the body
Know the different tolerance classes, we continue to describe the effect, the change, that occurs in the body in each of the different types of room.
Pharmacodynamic or functional tolerance
Due to the repeated consumption of the substance, the concentration of neurotransmitters (NT) in the synaptic space increases, this increasing number of NT therefore generates a decrease in the number of neural receptors, not constantly sending signals to the cells.
This decrease in receptors is called downregulation.. Likewise, it is also possible that the receptors become less sensitive, exhibiting a higher activation threshold.
On the contrary, if there is a decrease in neurotransmitters in the synaptic space, the receptors will increase in number or become more sensitive to take advantage of all that is available. This process is called regulation of receptor discharge.
An example would be the decrease in the number and sensitivity of GABA A receptors after persistent alcohol consumption.
Pharmacokinetic or metabolic tolerance
As we pointed out above, this tolerance is linked to the faster decrease in the amount of substance in the body. In other words, it is after repeated consumption, the metabolism becomes more and more efficient in breaking down and eliminating the drug.
For example, in the case of alcohol, there would be an acceleration of metabolism induced by liver enzymes, as is the case with enzymes of the cytochrome P-450 system.
Influence of context on drug addiction
The influence of context on drug addiction, it produces what is called in psychology conditioned tolerance, concept proposed by Siegel, defined as the relation produced between the contextual signals where the substance is consumed and the response given by the organist to this consumption.
This would mean that, in the usual context where the drug is consumed, the effects are reduced, attenuated, by the compensatory conditioned response produced by the environment, this response generally appears in the opposite direction to this effect produced by the substance.
He also tries to explain tolerance from the opposite process theory of Solomon and Corbit (1974) or acquired motivation theory.
This theory asserts that, when there is an intense emotional change, whether it is very positive or very negative, it is usually accompanied by the adversary’s affection. The first intense emotional change will be called “process a” and the affect of the adversary will be called “process b”.
In the early stages of drug use, the substance produces pleasure; in these first moments the “process b” is already activated, linked to a feeling of displeasure, but to a lesser extent than the “process a”. This will increase the “process a” and the “process b” in the calculation of the “process a”, generating, as already pointed out, a feeling of pleasure.
Now, with repeated consumption, the “a-process”, which produces pleasure, weakens. This fact is explained by the habit that appears in the drug, tolerance. Instead, “process b” will continue to increase, becoming more intense and increasing feelings of discontent.
This event it is linked to the onset of abstinence. This is ultimately the strongest effect and what prevails is “process b”, thus provoking aversive motivation which will lead to wanting to avoid the withdrawal syndrome.
Control of established tolerance
As we presented in the previous section, tolerance may be due to a state of environmental conditioning. So, it could be eliminated or diminished using quenching, non-contingent reinforcement or external inhibition.
With regard to extinction, a process that appears due to the lack of response to a previously enhanced stimulus, it has been shown to occur in front of different types of substances, such as morphine, and in front of different pathways. administration, such as, for example, intravenously.
On another side, the noncontingent reinforcement process, consisting of a presentation, does not appear conditioned stimulus (CE) and unconditioned stimulus (EI). That is, the onset of AC will signal the non-presentation of IE. It has obtained positive results in decreasing tolerance to the sedative effects of morphine in rats.
Finally, with regard to external inhibition, various authors have pointed out that the reduction in drug addiction is due to the introduction of a new stimulus in the context. This would produce a new stimulus-driven response, which interferes with the emergence of tolerance. The effect of external inhibition would also strengthen the belief in the environmental specificity of the room.
As an example of what this section presents, we will cite Linnoila (1986) who pointed out that: circumstances not normally associated with ethanol, such as in a car ”.
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