Drug Habituation: What It Is, Types, Causes And Characteristics
Drug habituation, better known in psychology as tolerance is defined as the state of adaptation of the organism to the drug.
When we begin to consume any type of drug, we observe that small amounts of it produce great effects, changes and sensations in the person. Large quantities are not necessary for our behavior to be altered by the narcotic. But if we continue consuming the same drug or similar drugs, we will notice that it does not produce the same effect as it did at first; generally, this will be lower, indicating that our body has become accustomed to the drug.
In the following article we will define the term tolerance, as well as see that it is divided into different types; We will also know what changes occur in our body when it becomes habituated and we will see that the environment also influences the drug tolerance process.
Keep reading if you want to know what changes the repeated consumption of a narcotic generates in your body, why its effect is reduced or how to reduce habituation.
Drug habituation, or also called tolerance, is defined as the state of adaptation of the organism that 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 that were obtained initially. In other words, it is the decrease in the effect of the drug when consumed repeatedly.
Before continuing with the specific case of drug habituation, let’s see how Psychology describes the term habituation.
Habituation characteristics
Habituation as a general concept in Psychology is explained as the decrease in the individual’s response to a stimulus presented repeatedly It is a central process, that is, it is produced by a change in the central nervous system (CNS) and not by a state of fatigue of the individual or by a sensory adaptation. The response is innate, differing from extinction where learning did occur.
Some of its properties are stimulus specificity, this means that there will only be a decrease in the response to the specific stimulus that has produced habituation and generalization, habituation to the specific stimulus occurs in different situations.
This process can present spontaneous recovery, which means that, As time goes by, the response to the stimulus that had decreased due to habituation increases again, returning to the initial state
Once the habituation process is understood and more specifically that of habituation to drugs, we will move on to see what type of drug tolerance exists.
Types of drug habituation
In this section we will define the two types of drug habituation 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 habituation to the drug appears after repeated administration of the substance a process that causes the degradation mechanisms of this drug to accelerate.
In this specific case, the change occurs especially in the substance, which presents a faster decrease in concentration in the body, caused by the acceleration of its degradation.
2. Pharmacodynamic, pharmacological, neural or functional tolerance
This variant of habituation occurs when, after repeated consumption of the substance, The drug receptors become accustomed to its presence, generating a state of adaptation of the organism to the substance and, consequently, higher doses are needed than those initially required.
Unlike the other type of habituation, pharmacodynamic tolerance causes greater change in the body, since in the places where drugs are received in the brain, there is an increase or decrease in the number and sensitivity to the substance.
cross tolerance
Having mentioned the two types of tolerances, we will go on to describe two other terms linked to drug habituation.
We will refer to this process when the consumption of a specific substance generates not only habituation to it, but also Tolerance to other similar drugs will also occur
This would be the case, for example, of people with tolerance to alcohol, who will also show tolerance to tranquilizers, needing higher doses of these to notice an effect.
The reverse tolerance
Reverse habituation appears when, after consuming similar or even lower doses of the same drug, similar or greater effects are obtained thus presenting a result contrary to that expected by habituation, hence the name inverse tolerance.
This paradoxical process is possibly due to the accumulation of the drug in certain tissues of the body and its subsequent release, or to a hypersensitization of the substance’s receptors. That is, an increase in the function or number of receptors.
Given the effects related to reverse tolerance, this It is linked to the occurrence of overdose, without the dose taken being greater than that normally consumed
Biological effects that habituation produces in the organism
Knowing the different kinds of tolerance, We move on to describe the effect, change, that occurs in the body in each of the different types of room
Pharmacodynamic or functional tolerance
Due to repeated consumption of the substance, the concentration of neurotransmitters (NT) in the synaptic space increases, this increasing number of NT consequently generates a decrease in the number of neuronal receptors, so as not to constantly send signals to the cells.
This decrease in receptors is called downregulation Likewise, it is also possible that the receptors become less sensitive, presenting a higher activation threshold.
Contrary, If there is a decrease in neurotransmitters in the synaptic cleft, the receptors will increase in number or become more sensitive to take advantage of all that is available. This process is called receptor upregulation.
An example would be the decrease in the number and sensitivity of GABA A receptors after persistent alcohol consumption.
Related article: “Types of neurotransmitters: functions and classification”
Pharmacokinetic or metabolic tolerance
As we have already pointed out previously, this tolerance is related to the more rapid decrease in the amount of the substance by the body. That is to say, After repeated consumption, the metabolism becomes increasingly 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, such as the enzymes of the cytochrome P-450 system.
Influence of context on drug habituation
The influence that the context exerts on drug habituation, produces what in Psychology is known as conditioned tolerance a concept proposed by Siegel, defined as the relationship 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, its effects are reduced, attenuated, by the conditioned compensatory response produced by the environment, this response generally appears in the opposite direction to the effect produced by the substance.
An attempt is also made to explain tolerance based on Solomon and Corbit’s opponent process theory (1974) or theory of acquired motivation.
This theory states that, When an intense affective change occurs, whether very positive or very negative, it is usually accompanied by opposing affect The first intense affective change will be called “process a” and the opposing affect will be called “process b.”
In the initial phases of drug consumption, the substance produces pleasure; In these first moments, “process b” is already activated, related to the feeling of displeasure, but to a lesser extent than “process a”. This will make “process a” greater in the calculation of “process a” and “process b”, generating, as already noted before, a feeling of pleasure.
Now, with repeated consumption, the “a process,” which produces pleasure, weakens. This fact is explained by the habituation that appears to the drug, tolerance. On the other hand, “process b” will continue to increase, becoming more intense, and the feeling of displeasure will increase more and more.
This event is related to the onset of abstinence That is, finally the strongest effect and the one that prevails is “process b”, thus causing the aversive motivation that will lead to wanting to avoid the withdrawal syndrome.
You may be interested: “Drug withdrawal syndrome: its types and symptoms”
Control of established tolerance
As we have presented in the previous section, tolerance can be due to a state of environmental conditioning. Therefore, could be eliminated, or diminished, using extinction, noncontingent reinforcement, or external inhibition
Regarding extinction, a process that appears due to the non-presence of a response to a previously reinforced stimulus, it has been seen that it occurs with different types of substances, such as morphine, and with different routes of administration, such as, for example. , the intravenous.
Besides, the non-contingent reinforcement process, consisting of the presentation, does not pair the conditioned stimulus (CS) and the unconditioned stimulus (US) That is, the appearance of the EC will indicate the non-presentation of IS. It has obtained positive results in reducing tolerance to the sedative effects of morphine in rats.
Finally, in reference to external inhibition, different authors have pointed out that The reduction in habituation to the drug would be due to the presentation of a novel stimulus in the context This fact would produce an orientation response to the new stimulus, which interferes with the emergence of tolerance. The external inhibition effect would also reinforce the belief in the environmental specificity of the room.
As an example of what is presented in this section we will quote Linnoila (1986) who pointed out that: “It is possible that subjects who show tolerance to the effects of ethanol in a meeting or in a bar, lose that tolerance when they are in circumstances not normally associated with ethanol, such as in a car.”
