Drug use and abuse is a serious social and health problem worldwide. Substance abuse kills, directly or indirectly, about 11.8 million people annually.
Alcohol and nicotine take the dubious prize when it comes to lethality: Because of them, 11.4 million people die earlier than expected each year. According to the WHO, up to half of people who use tobacco end up dying because of it.
The prevalence of substance use disorders is estimated at 1.5% of the world’s population, although in some disadvantaged regions this percentage increases to 5%. No matter how low these data may seem, don’t be fooled: one in 5 people in the world (20%) consume tobacco. The fact that addictive behavior is not reflected in epidemiological data depends solely on whether the person is lucky in not paying for this dependence at a physiological level.
With all the statistics we only want to make it clear that the consumption of addictive substances claims as many lives and causes as many pathologies as many pandemic events caused by viruses and bacteria. With the intention of taking a more biological and anatomical approach to this global problem, here we will review the topic of how drugs affect the nervous system
The World Health Organization (WHO) defines a “drug” as any therapeutic or non-therapeutic substance that, introduced into the body by any route of administration, produces an alteration, in some way, of the natural functioning of the individual’s central nervous system and It is also susceptible to creating dependency. It should be noted that the dependence developed can be physiological, psychological or both.
The American Psychological Association (APA) recognizes several types of drugs in use, encompassed in 10 categories different: alcohol, caffeine, cannabis, hallucinogens, inhalants, opioids, sedatives, hypnotics (including anxiolytics), stimulants (cocaine and others) and tobacco. These are the substances that are considered addictive today, but surely not the only ones.
Among the activities that can generate dependence, currently only one is considered potentially pathological: gambling. Surprisingly, it has been shown that the altered reward circuit in a gambling addict responds in a similar way to the stimulus (winning a cash prize) as a cocaine addict does when receiving a new dose. Other activities that could share mechanisms with drugs are still being evaluated, such as video games, compulsive shopping, and chronic exercise.
Drugs and their effect on the nervous system of the human body
Let’s start with the most basic: nicotine. When a person smokes a cigarette, nicotine passes into the bloodstream, then to the brain and In just 7 seconds it produces excitation in part of the neurons located in the ventral tegmental area (VTA), which send signals to the nucleus accumbens. The latter is responsible for producing dopamine, the neurotransmitter and hormone that makes us feel that “rush” or shock of well-being.
In the case of tobacco, this sensation is very ephemeral, because as soon as the nicotine acts it stops doing so: the physiological peak of this drug is 7 seconds and its decline range is another 7. Furthermore, The more the neurons and circuits of the nucleus accumbens are exposed to the substance, the more of it will be needed to elicit the desired response. This is how tolerance and long-term dependency are generated.
To find out how drugs affect the nervous system, we can turn to another much more aggressive one: heroin. This drug quickly enters the brain, adheres to the opioid receptors of cells located in different areas and causes changes in the excitability of neurons, stimulating the presynaptic release of gamma-aminobutyric acid (GABA), among other things.
When you come into contact with this drug at the nervous level, a generalized sedative effect and indescribable well-being occur (the level of dopamine in the described reward system is increased by 200% in experimental models). All of this causes euphoria, drowsiness, a feeling of heat and gradual loss of consciousness, accompanied by a powerful analgesic effect. People who have consumed it do not lie when They claim to be “in a cloud” in the moments after the injection.
Finally, we can dissect the nervous effects of cocaine, the third of the most present drugs in general culture. Once consumed, the effects on the central nervous system are noticeable in a matter of 10 seconds (inhaled) and 3-5 minutes, if consumed intranasally. This compound inhibits the action of monoamine transporters, resulting in vasoconstriction in the blood system, elevation of blood pressure, tachycardia, and increased cardiac output. All this reports a very characteristic feeling of activation and euphoria.
Chronic cocaine abuse puts the patient at risk for many events, including stroke, subarachnoid hemorrhages, intraparenchymal hemorrhages, and many other things. In general, every drug addict is seven times more likely to suffer an ischemic heart attack, a value that is multiplied even more in those who use cocaine.
Beyond all these mechanisms, it should be noted that dependence alone also modifies the functioning of the patient’s nervous system. When withdrawal syndrome occurs (within 72 hours of completely stopping the use of a substance), the person experiences anxiety, restlessness, difficulties concentrating, nervousness, stress and other associated sensations. The addict’s brain can only function “normally” with the presence of the chemicals described. When they are withdrawn, the nervous system fails.
Summary
As you have seen, drugs have a similar function to that of normal neurotransmitters circulating in the human body: They reach an area, stimulate or inhibit cellular activity and generate a short-term response When its peak activity ceases, the individual physiological state returns to normal, but as dependence is generated, reaching this “normality” is increasingly complex.
Furthermore, you must keep in mind that we have moved on purely physiological grounds. Addiction to a substance can also have psychological bases and, therefore, there are people who can manifest addictive mechanisms towards substances that the body does not really need at the time of crisis. Without a doubt, we still have a lot to investigate as a society to elucidate the mechanisms of dependency in the human mind.
