5 Substances That Cause the Most Addiction and Their Effect on Our Brain

That some drugs, alcohol and nicotine do with our body.


This rating is compiled by British psychiatrist, professor of neuropsychopharmacology, David Nutt and his research team.

5 Substances That Cause the Most Addiction and Their Effect on Our Brain

1. Heroin

Heroin is an opioid drug, the use of which develops a strong mental and physical dependence. This is due to the fact that when injected, the substance quickly penetrates the brain, easily overcoming the blood-brain barrier between the circulatory and central nervous system. In the brain, it causes increased dopamine production. Experiments on experimental animals showed an increase in the level of this pleasure hormone by 200%.

Heroin mimics the naturally occurring substances in the brain that nature created to control pain and increase pleasure.

An additional mechanism of addiction is the increased production of an exciting mediator of glutamate. Together with severe withdrawal symptoms – pain, anxiety, cramps, insomnia – this leads to severe dependence. Breaking begins 4-24 hours after taking the last dose, and the addict is in dire need of another dose of the drug. In addition, the body quickly develops tolerance for heroin – each time a person needs a bigger and bigger dose.

Heroin addicts often die from heart attacks, strokes, since the drug affects the state of the cardiovascular system. Another cause of death is the depletion resulting from constant CNS stimulation. Experts assigned this drug three points out of three possible according to the degree of formation of dependence.

2. Cocaine

Cocaine is an alkaloid found in plants of the genus Erythroxilum. In nature, it acts as an insecticide and protects the leaves of shrubs from being eaten by insects. Cocaine has a powerful stimulating effect on the central nervous system, causing a feeling of euphoria.


Typically, the reward system in the brain works according to certain rules. A neurotransmitter – in this case, dopamine – enters the space between neurons called the synapse. Specialized receptors transmit a signal to respond to its appearance, then remove the neurotransmitter from the synapse to stop its effect.

Cocaine blocks dopamine reuptake systems, causing it to work again and again, leading to a whirlwind of pleasure.

However, cocaine euphoria does not last forever, and after the completion of the drug’s action, a phase of a depressed state occurs. Other side effects include fatigue, anxiety, and insomnia.

Cocaine is dangerous for the cardiovascular system. It causes powerful cramps that can lead to cerebral hemorrhage, disrupt the functioning of the heart or other organs. Another negative effect is the state of acute psychosis, in which a person has little control over himself. In addition, there is a myth that cocaine is not addictive, but it is not so.


3. Nicotine

Nicotine, like cocaine, is an alkaloid that naturally performs the function of controlling insects. This is the main component of tobacco, which is addictive. Nicotine is rapidly absorbed by the lungs and transported to the brain. It increases the activity of nicotinic acetylcholine receptors, which leads to the release of adrenaline. This temporarily stimulates various systems of the body, and a person feels cheerful and active. And the release of dopamine accompanies smoking with a sense of pleasure.

Nicotine is toxic, long-term use contributes to the development of cancer, ischemia, angina pectoris and so on. WHO approve that up to 50% of smokers die for addictive reasons.

4. Barbiturates

Soothing and hypnotics based on barbituric acid have a depressing effect on the central nervous system. Depending on the dosage, medications can have a mild relaxing effect or lead to a coma.

Barbiturates stimulate inhibitory neurotransmitter receptors – gamma-aminobutyric acid, as a result of which the transmission of impulses to the central nervous system slows down. This leads to muscle relaxation, calming, eliminates anxiety. The problem of drug dependence was hushed up for a long time, but subsequently recognized and refused from barbiturates in favor of benzodiazepines.


Moreover, if cocaine and heroin are illegal, then these drugs have been relatively affordable for a long time, which increases their danger.

5. Alcohol

Absolutely legal in most countries, alcoholic beverages are named the most dangerous drug in the world. They also cause addiction quickly enough. Animal studies have shown that alcohol increases 40–360% dopamine levels.

Alcohol enhances the effect of gamma-aminobutyric acid (GABA) – the main inhibitory mediator of the nervous system. Therefore, the movements and speech of drunk people slow down, and the dose of alcohol relaxes. GABA gradually adapts to changes, reducing the activity of the corresponding receptors, which makes the brain dependent on alcohol.

If a person stops drinking alcohol, the decreased activity of GABA receptors leads to a weakening of the function of neural inhibition, and the brain becomes more excitable.

At the same time, ethanol reduces the ability of another neurotransmitter – glutamate – to act on NMDA receptors. With long-term use of alcohol, the number of these receptors increases. The brain becomes less susceptible to alcohol and more susceptible to glutamate. This increases excitability, leading to symptoms of withdrawal symptoms: convulsions, anxiety.

One more reason Formation of addiction – the ability to quickly receive energy to power the brain. For this, acetate is required – an intermediate product of ethanol metabolism. The brain sits on a simple source of energy. In the body of a regularly drunk person, alcohol replaces the usual source of energy – glucose.

According to WHO, 3.3 million people die every year in the world due to alcohol consumption. The statistics include concomitant drunkenness diseases and injuries.

Dr. Nutt himself noted that the legal status of a drug is not necessarily related to addiction or harm from it. Tobacco and alcohol are high in the ranking, but remain legal

However, the existence of this list does not mean at all that substances that did not get into it do not cause addiction. Therefore, the rating should not be taken as a tool for dividing drugs into harmful and non-harmful. The use of any psychoactive substance has consequences.

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