Drugs are substances that generate in people who use them an effect on their mental life, which they tend to value as pleasant at the time they express themselves, but which end up severely conditioning the way they carry out their daily activities.

Because all drugs involve (in a way) the manipulation of our central reward system, vitiating the “magnetism” of the compass that guides our motivations and goals in life. This is how the phenomenon we know as “addiction” or “dependence” happens.

The effects of any substance in our brain can be divided into three categories , namely: stimulant (generation of euphoria and increased activity), psychodysleptic (alteration of perception) and depressant (deep relaxation of physiological and cognitive activation).

In this article we will deal precisely with the last of them, highlighting several of the most frequently consumed nervous system depressant drugs in the world. Special attention will be given to their effects and the way they alter thought and behaviour.

Nervous system depressant drugs

Central nervous system depressant drugs have the property of inducing states of deep muscular relaxation, as well as a laxity of consciousness and a slowing down at the cognitive level and of physiological processes such as breathing or heart rate. All of them have the property of exerting synergetic effects when consumed in combination, so that the concomitant use of two or more of them can lead to coma or even death. In addition, they have been shown to generate tolerance and withdrawal (which is the opposite of the effect of intoxication).

Another aspect that should be known is that of cross-tolerance. The consumption of a drug from this family means that a higher and higher dose is needed to obtain the same effect as at the beginning, but all this can be extended to all of them. Thus, if someone develops this process with alcohol, he or she will show an attenuated reaction to the effect of the anxiolytics when consuming them separately. Let us see in the future what these drugs are and their most important characteristics.

1. Alcohol

Alcohol is the generic name given to ethanol . It comes from the aerobic fermentation of the sugar contained in some fruits (grapes, apples, etc.) and grains (rice, barley, etc.), mediated by the activity of fungi such as yeasts. In general, it is feasible to differentiate their presentation in two different categories: fermented beverages (wine, beer, etc.) and distilled beverages (whisky, rum, gin, etc.), the latter containing a higher percentage of this substance (thirty degrees or more).

Alcoholic beverages are defined as all products containing at least 1% ethanol in their composition (or one degree, which would be an equivalent measure); and a very wide range of spirits and beers marketed as “non-alcoholic” fall into this category. The calculation of the grams of this substance would be made by simply multiplying its grades (in every 100 cc of liquid) by 0.8, a figure which corresponds to its density.

When the substance is ingested, 80% of it is absorbed by the small intestine, and the remaining 20% by the stomach. In addition, crosses the blood-brain barrier and the placental barrier , so it would reach the brain and the fetus in the case of pregnant women (acting as a very dangerous teratogen and increasing the risk of multiple problems in the newborn).

In turn, women get intoxicated more quickly and have a higher risk of the substance harming their bodies. When alcohol is mixed with gas (carbonated drinks) or used on an empty stomach, the arrival of its effect is accelerated.

It could be said that alcohol-induced drunkenness involves going through a series of distinct stages . In the first place, the person may experience well-being and a tendency to laugh easily, accompanied by loquacity and behavioural disinhibition (so he dares to interact with others in a less “apprehensive” way).

Progressively, as consumption continues, there is a state of sedation and a hindrance to movement, with slurred speech and a substantial loss of reflexes. Finally, a state is reached in which consciousness is altered, lacunar amnesia and breathing difficulties arise. At this point, the risk of coma and death (from respiratory depression) is present.

Despite being a drug that can be legally acquired without any problem, and even being a common guest at many celebrations and parties, alcohol generates addiction and is associated with multiple pathologies in different organs and systems. Its use is particularly harmful in the case of women , due to intersex discrepancies in the body’s distribution of adipose tissues and the enzymes responsible for their metabolization.

2. Benzodiazepines

Benzodiazepines are drugs prescribed to treat some of the disorders in the global category of anxiety, and more particularly those with a physiological symptom profile (e.g. panic). They act on our brain by affecting GABA, the most important inhibitory neurotransmitter for humans, which reduces the basal level of cortical activation. Its effect begins about ten or fifteen minutes after its consumption by mouth, through which it is easily absorbed.

Its impact on the organism attenuates the way in which the sympathetic nervous system precipitates its own anxious physiology . That is why it is used in the treatment of this symptom, despite the fact that it can generate addiction among those who consume it for long periods. Thus, it has been described the appearance of both an abstinence syndrome (discomfort when stopping consumption or not having this compound) and tolerance (need to increase the dose to achieve the same effect as at the beginning). In some cases, it also leads to hostility and irritability.

When consumed in higher doses they can induce sleep, or in other words, acquire hypnotic properties (reducing the time between access to bed and reconciliation). However, their use modifies their structure: it shortens phase 1 (light sleep), prolongs phase 2 and practically cancels out phases 3 and 4 (deep sleep). It is for this same reason that it is a priority to provide sleep hygiene strategies , and to reserve this drug only for cases of extreme need, maintaining it for a maximum of three or four weeks.

In addition to the anxiolytic/hypnotic effects, this medication induces myorelaxation by its action on the basal ganglia, cerebellum, and spinal cord; and anticonvulsant effects, including spasms that occur during alcohol withdrawal. This is why its use can extend to health problems very different from anxiety, such as contractures in muscle fibres and detoxification from other substances.

Side effects of its administration include dizziness (especially in older patients whose liver and/or kidney function is impaired), excessive sedation, headaches, inhibited sexual desire, erectile dysfunction, insufficient lubrication, joint involvement during speech production (dysarthria/dysphasia), tremor, diarrhea, or constipation. Cases of antegrade amnesia have also been detected , that is, a hindrance to the process of storing information in the long-term memory store. Such problems make academic and work activities difficult and significantly reduce the quality of life.

Nevertheless, these drugs have a better safety profile than the ones used before them: barbiturates. Adhering to what the physician stipulates through his clinical judgment, without increasing the dose or prolonging the treatment time, is basic to minimizing the risk of addiction.

3. Barbiturates

Barbiturates are non-selective nervous system depressants. They consist of barbituric acid (a combination of urea and malonic acid from apples) and two carbon radicals.

Until the 1960s it was the most commonly used anxiolytic , despite being sadly famous for the high number of fatal intoxications it produced worldwide (since the therapeutic and fatal doses are too close together). This fact, together with its enormous addictive capacity, made it necessary to discourage its therapeutic use and to replace it with the new anxiolytics (when they were synthesized).

Currently are only used for intravenous anaesthesia in certain surgeries, and also for resuscitation of head injuries. Finally, sodium phenobarbital is still used for epilepsy, which is one of the most common causes of death from respiratory depression worldwide (especially when combined with alcohol).

4. GHB

GHB (gamma-hydroxybutyrate) is another of our brain’s depressant drugs, which is often labeled as liquid ecstasy . The truth is that this is a misnomer, since ecstasy (or MDMA) is a chemical compound whose effect and mechanism of action are different from those of GHB. The latter is usually presented as a transparent and slightly salty liquid, which facilitates its “camouflage” in drinks of all kinds without the change in taste being practically perceptible, which is dangerous for anyone who may drink it inadvertently (since it enhances the effect of alcohol and facilitates an eventual overdose).

This is a popular drug at rave parties, which were traditionally held underground and where all kinds of substances were used along with electronic music and colorful lights. The consumption of GHB induces a state of “euphoria” and disinhibition due to depression of the prefrontal cortex , something that on many occasions ends up being expressed as acts of violence. Many of those who use it recognize hallucinations in visual mode, so that a response of agitation and nervousness is precipitated, leading to the collapse of the emotions.

The effect of the substance reaches its peak approximately 10-20 minutes after consumption, which is why the possibility of using it as a sleep-inducer and anesthetic was formerly postulated. Later it had to be ruled out because of the perceptive alterations it caused and also because of its numerous and disabling side effects (dizziness, nausea, diplopia, drowsiness and headaches). The effect of the drug lasts for two hours , but with a residual stage that doubles its duration. Its origin is synthetic (it comes from artificial synthesis in a laboratory).

Sometimes it is presented as a whitish powder, which makes it easier to assess the associated effect according to the dose administered (in grams). It is estimated that from four grams it can induce a state of sleep that is extremely difficult to interrupt, as well as a dissolution of consciousness that ultimately implies comatose states.

5. Kava

Kava is a substance that is sold as an alternative medicine for the treatment of acute states of anxiety, although there is no evidence as yet of its possible beneficial effect in this regard. It comes from a plant of Polynesian origin (piper nigrum) directly related to pepper, and is widely used in regions along the Pacific Ocean. Its effects are similar to those of other depressant substances described in this text, and include a state of calm and relaxation in which the full integrity of the higher cognitive functions is maintained .

Although there are some studies on the substance from which addictive properties are inferred, what is really true is that there is not yet any definitive evidence on this point either. It is usually presented in the form of a drink, and its active ingredients are called kavalactones. All the possible harmful effects that could be attributed to this substance, including its hepatotoxicity and possible tissue apoptosis, are still under study.

6. Heroin

Heroin is one of the most addictive drugs that have been documented . It is made from morphine, which in turn is extracted from the opium poppy. It comes in the form of a white powder, or as a blackish sticky substance. Some of its users mix it with cocaine (speedball), resulting in a mixture that has led to the death of many people over the last few decades. In the latter case, the route of consumption is by injection, although the heroin is also administered by smoking and inhaling, which speeds up its access to the nervous system and the time it takes for it to take effect (by attaching itself to the opioid receptors).

Initially, this drug was synthesized to replace morphine for military use, since many soldiers returned home (after the first major war) suffering from harmful chemical dependency. It was also sold with the innocent aim of treating common coughs and diarrhoea. Finally, however, was withdrawn from the market for safety reasons; although its use spread as an illegal practice unstoppably, especially in the 1960s.

Its consumption produces a relevant dryness in the mouth (xerostomia), flushing, heaviness in the arms/legs, nausea, diffuse dermal itching, cognitive slowing, deep sleep and vomiting. When stopped, unbearable joint pain, flu-like symptoms, uncontrollable diarrhea, tremor, and desperate search for the substance can occur. The effects of withdrawal can sometimes be quite severe, forcing the use of partial agonist damage control treatments (methadone).

As time goes by, if its use does not cease, major complications may arise. The most relevant ones are the damage to the structure of the nasal cavities (in the case of the inhaled route), insomnia in any of its phases, pericarditis (infection of the tissue that covers the heart), alterations in the sexual sphere, chronic constipation, problems in the emotional life (mainly depression) and a degradation of the renal and hepatic functions. Social ostracism is also very common, which aggravates the problem and makes it difficult to achieve adequate reintegration .

In other cases, the misuse of syringes and intravenous equipment can lead to chronic infection by heroin users (HIV, hepatitis, etc.), which is an additional health problem for which separate therapeutic solutions must be provided. Finally, there is a relevant risk of overdose, derived from the synergetic effects of its combination with other depressants, or from its use in an unusual or infrequent space (due to conditioned tolerance).

Bibliographic references:

  • Barerah, S. (2018). Forms of Drug Abuse and Their Effects. Alcoholism and Drug Abuse Weekly, 1. pp. 13 – 19.
  • Dassanayake, T., Michie, P., Jones, A., Carter, G., Mallard, T and Whyte, I. (2012). Cognitive Impairment in Patients Clinically Recovered From Central Nervous System Depressant Drug Overdose. Journal of clinical psychopharmacology, 32, 503-510.