What is addiction, it is clear to a non-specialist – it is impossible to stop using a substance, despite the fact that the person knows the harm that this substance causes. From the point of view of neuroscience, this problem arises because of changes in the reward system. This is the name of the system of neural connections in the brain that is responsible for ensuring that a person has the motivation to achieve vital goals. The reward system links the satisfaction of biological needs to pleasure. The brain rewards the body for having solved the necessary task for survival.

Defects in this system occur due to genetic or prenatal factors and as a result of systematic use of psychoactive substances.

The presence of an innate predisposition to breakdowns in the reward system does not mean that there are people who are doomed to become drug addicts. Just as with other diseases, innate risks only increase the level of risk, but do not determine the fate of the individual.

The beginning of the use of psychoactive substances does not occur because a person from birth feels the need to stupefy the mind. The first introduction to drugs is due to social circumstances. Continued use is also supported by psychosocial factors. But the development of pathological dependence is mainly a neurobiological process.

It is good if the social environment helps to train the reward system. A person who is accustomed to the fact that pleasure is preceded by emotionally monotonous activity is less likely to develop an addiction. Everyone knows about this important social competence — the ability to postpone pleasure — since childhood. Proverbs like “Do the job, walk boldly” are about it, and Freud’s teaching about the pleasure principle, which is opposed to the reality principle, is about it.

If the reward system is activated by taking a substance, this event cannot be considered a manifestation of pathology. Use is not a disease. We can talk about pathology when the use of impulsive turns into compulsive, i.e. free choice becomes impossible and human behavior falls under the power of the biological mechanism of dependence.

This is a very complex mechanism involving many neurotransmitters and neural networks. The main role in the reward system of dopamine in the mesolimbic region. When there is something worthy of remuneration, the level of dopamine increases. The drug raises dopamine very quickly and very high in the neural networks involved in the reward system. It may be that natural pleasures, including the satisfaction of achieving a goal (for example, passing an exam), can cause an equally strong increase in dopamine, but they definitely can’t do it so quickly. Pleasure, which occupies its logical position in the motivational reward system, in normal circumstances follows the receipt of some positive information. Injecting the drug into the body simulates receiving this information and triggers the corresponding biological response in the mesolimbic region of the brain.

One of the most impressive advances in addiction research has been identifying the target of each of the most commonly used drugs. All drugs increase the level of dopamine in one way or another, but they do it in different ways. Stimulants block the transport of dopamine or increase the release of dopamine. Opiates act on opioid receptors in a way that increases dopamine. Nicotine stimulates nicotine receptors, and this also increases dopamine. Alcohol affects dopamine levels in an indirect way, it mainly targets GABA and glutamate receptors.

Stimulants affect the minimum number of neurotransmitters. Their main goal is dopamine. The response of the greatest number of different neurotransmitters is observed when alcohol enters the body. The effects of alcohol in this sense are very diverse.

These opioid receptors play an important role in the formation of addiction. Under normal conditions, thanks to the opioid system, a person does not just coldly fix the fact of satisfying desires, but experiences pleasant feelings, in some cases pleasure. Addiction is more likely to form when a psychoactive substance causes a strong sense of pleasure (euphoria), i.e., affects the opioid system in the brain.

Thus, the main mechanism of action of narcotic substances is related to dopamine in the limbic system. However, constant drug use leads to molecular changes in several neurotransmitter systems. Moreover, all chemical dependencies are variants of a genetically unified disease, and the type of drug only affects the speed and intensity of the development of dependence.

To understand disorders associated with the use of various types of psychoactive substances, you need to have a good understanding of the Pavlovian model of conditioned reflexes. In this case, Pavlovian conditioning works like this: the drug simulates a “reward” situation in the brain in a matter of minutes, which at the biological level means first of all a sharp jump in the level of dopamine; the brain regions responsible for memory record the connection between drug use and biological reward. When this pattern is fixed, the very thought of being able to take the drug causes a rise in dopamine. A person has a strong passion that can displace everything else from life.

The transition from free (controlled) consumption to compulsive (uncontrolled) consumption is not only associated with a violation of the regulation of the reward system. There is another system that is involved in pathological addictions — the stress response system. Long-term drug use has a more powerful effect on this system, and not on the reward system. Over time, the neural networks involved in the reward system stop responding to the drug as much as they did the first time. Because of the weakening reaction, you have to increase the dose. In narcology, this is called tolerance.

The stress response system, on the other hand, becomes more and more active over time. The essence of what is happening to her is that periods without “reward” are experienced by the body as stressful and the strength of these unpleasant experiences is constantly growing. A person begins to feel bad simply because they do not receive a narcotic “reward”.

During periods of abstinence, the level of neurotransmitters that the drug increases (dopamine and serotonin) decreases. Hence the painfully low mood, difficulties with getting pleasure from life. The stress response system is also abnormally activated. The level of stress hormones and norepinephrine increases, and unpleasant conditions such as increased anxiety and panic attacks appear.

Tolerance is one of the diagnostic criteria for addiction. Despite the fact that addictions have long been known to mankind, for a long time there were no clear diagnostic criteria for separating conditionally normal use from pathology. The first diagnostic manuals in modern psychiatry contained rather vague descriptions of the symptoms and signs of alcoholism and drug addiction.

By the mid-1970s, psychiatrists agreed that the presence of three signs indicates the painful nature of the use of a substance. First, compulsivity, i.e. an irresistible attraction, the inability to refuse. Second, tolerance, the movement to higher doses and more frequent use. Third, withdrawal syndrome. Withdrawal syndrome refers to the deterioration of health after stopping taking a psychoactive substance. To these three points, of course, it is worth adding the social aspect of addiction. The hierarchy of priorities in the life of a dependent person is built to the detriment of professional realization and family.

In the 2000s and 2010s, the thesis that the development of addiction does not necessarily require the presence of a psychoactive substance — a drug-is widely spread and studied. The popularity of this idea is due to the fact that neuroscientists and clinicians, with neuroimaging technologies and solid laboratory resources, turned to the topic of behavioral addictions.

Non-chemical or behavioral addictions are a group of diseases that are similar in their mechanisms of development and clinical manifestations to addictions to psychoactive substances. However, in behavioral addictions, the dopamine reward system is stimulated not by the drug, but by other stimuli — certain behavioral acts that affect the reward system as a psychoactive substance. Recent research points to important phenomenological similarities between addictive behavior disorders and drug addiction. Dependencies of the two types often accompany each other. They also have a common characteristic: they initially give pleasure, and then progress to anhedonia (loss of pleasure), which requires constantly increasing the dose of the drug or the intensity of behavior.

Pathological gambling addiction (pathological gambling) was the first behavioral addiction not related to drug use that can be officially used as a diagnosis. It was classified as a mental disorder in 2013, when the American classification of mental disorders — DSM-5 was published.

The new classification caused a lively debate in the academic community. Not everyone agreed with her, but in the end, the presented clinical features common to gambling and substance use disorders convinced most experts. It was recognized that these disorders are United by the same neurobiological mechanisms. In particular, the reward system is activated in a similar way when gambling and drug use. The activation mechanism differs from that of impulse control disorders, which previously included a painful attraction to gambling. In impulse control disorders, there is a negative reinforcement of the reward system, when the individual experiences a sense of relief and pleasure as a result of performing a certain action. At the same time, before its completion, a person experiences mostly only unpleasant (negative) feelings.

In contrast, addiction to chemicals and gambling involves positive reinforcement (at least in the early stages), i.e. the person experiences positive emotions before the main event. It is only in later stages that compulsive features and negative reinforcement in the reward system begin to prevail.

With the development of the concept of behavioral addiction, new horizons have opened up for neuroscientists. In gambling addiction, there are no changes due to the neurotoxicity of psychoactive substances, so neuroimaging studies allow us to clearly see the key manifestations of the” pure ” addiction syndrome at the neurobiological level. Thus, in gaming addiction, there is a decrease in gray matter in the frontal cortex, hippocampus, amygdala, tire, thalamus, as well as in the orbitofrontal cortex and cerebellum. In substance-dependent cases, this decrease is much more pronounced.

People with addictions were found to have interesting associations of anatomical abnormalities of the brain with features of cognitive style. A decrease in gray matter in the frontal cortex of addicts is associated with making risky decisions and a distorted perception of deferred benefits. In gambling, a decrease in gray matter in the cerebellum and orbitofrontal cortex is associated with an irrational risk assessment (increased loss aversion).

Thus, neuroimaging allows you to see not only the similarity of gambling and substance dependence, but also to emphasize the difference between these disorders. The similarity of the neuroimaging picture of gambling with drug addiction is probably due to the fact that gambling, associated with maximum uncertainty of reward, can continuously activate dopamine systems. An important difference is that psychoactive substances increase dopamine to a superphysiological level, while in behavioral addiction it rises only to the upper limit of the norm. This explains the speed of development of addiction-from drugs faster, from gambling slower.

The concept of “sex addiction,” or compulsive sexual disorder, which is included in the new (as yet unreleased) concept, followed a similar path) International classification of diseases of the 11th revision (ICD-11). Compulsive sexual disorder is characterized by a persistent recurring inability to control a strong sexual drive, leading to repetitive sexual behavior for a long time (6 months or longer) and causing suffering and problems in personal life.

Diagnostic guidelines for psychiatrists take into account the risk of over-pathologizing sexual behavior. For example, individuals with high levels of sexual desire without behavioral control disorders and without problems in their personal lives do not qualify for a diagnosis of compulsive sexual behavior disorder. The diagnosis can also not be used to describe excessive sexual involvement in adolescents and related behavior (for example, Masturbation), even if it is associated with stress.

These clarifications are important if we take into account the tendency to self-stigmatization in some people. For example, when examining people who call themselves “sex addicts” or “porn addicts,” not everyone can be diagnosed with compulsive sexual disorder. If people feel shame and guilt about their sexual behavior, it does not mean that they suffer from compulsive sexuality. Although, research has shown that such people are sometimes shown treatment for other mental illnesses (for example, anxiety or depression).

Scientists do not have complete information about the role of the dopamine reward system or the opioid system in the development of compulsive sexual disorder. Whether it has a common neurobiological basis with drug addiction or gambling addiction is not yet known. For this reason, compulsive sexual behavior disorder is included in the ICD-11 group of impulse control disorders, and not in the group of substance use and dependent behavior disorders.

Another most common and most “biologized” type of behavioral addiction is food addiction. Painful dependence on food intake is similar to chemical dependence with the presence of a pronounced craving, withdrawal syndrome, or altered tolerance syndrome. The disorder is characterized by frequent, recurring episodes of binge eating (for example, once a week or more often, for several months). The episode of compulsive overeating itself is a separate period of time during which a person experiences a subjective loss of control over their diet, eats noticeably more than usual, and feels unable to stop eating.

Food addiction can be considered as an intermediate category between chemical and behavioral addictions. Any food is a chemical substance, but it doesn’t have the properties of a drug (cupcakes don’t count in Amsterdam). For the same reason as sexual compulsive disorder, paroxysmal overeating was not placed in the ICD-11 category of addictions, but was placed along with anorexia and bulimia in eating disorders.

The phenomenon of “nomadic” addiction syndrome is also interesting. For example, people with nicotine addiction who quit Smoking begin to eat boredom and stress, increasing dopamine levels with high-carb foods. The reward system of a dependent person seems to be looking for his weakest point, again and again returning to the drug or dependent behavior. Based on the substitution of one psychoactive substance for another, methadone therapy for heroin addicts in Western countries is no longer an experimental method, but is part of state programs.

The main problem with modern treatment is that addiction cannot be cured without destroying the person’s reward system and taking away their ability to enjoy themselves (i.e., without developing persistent anhedonia). Addiction for the reward system is something like a malignant brain tumor that has sprouted in vital centers, so that it cannot be surgically removed without killing the patient. All cases of recovery from addiction are related to the fact that the person was able to find something exciting and stimulating, like a drug (for example, religion, extreme sports, or a favorite job). Unfortunately, the risk of relapse will always remain very high.