This is your brain on drugs

An introduction to drugs

Drug: any chemical substance (excluding food and water) that alters the structure and function of the body. This is quite a broad definition — shampoo, soap, and moisturizer all roughly fit this description. But what we’re usually talking about when we talk about ‘drugs’ are psychoactive drugs. These substances lead to changes in the chemistry of the brain, altering perceptions, mood, thinking, and behaviour.

To know how drugs affect the body, it’s worth learning the difference between pharmacokinetics and pharmacodynamics. Pharmacokinetics is the study of the movement of a drug through the body, which is often dictated by the method of drug intake.

How you administer a drug has a significant impact on the drug’s effect and duration. Routes of administration such as inhalation, intravenous, and insufflation all deliver the drug to the brain very quickly; however, the faster a drug is delivered to the brain, the faster it will be broken down and its effects eliminated. Other routes of administration, such as oral ingestion or transdermal administration (on the skin), will have a slower onset, but the drug’s effect will last longer.

Pharmacodynamics, on the other hand, is the study of what a drug does to the body. In order for a drug to have an effect, it must be able to enter your brain and affect its cells. These cells are called neurons, and you’ve got roughly 100 billion of them. Neurons communicate with each other by secreting chemicals called neurotransmitters — psychoactive drugs alter the activity of these neurotransmitters, leading to changes in perception, behaviour, and mood. This is what we think of as a ‘high.’ Not all drugs affect everyone in the same way, but there are observable patterns for specific drugs.

The most common psychoactive drugs tend to fall into two categories: stimulants and depressants.

Central nervous system stimulants, or simply stimulants, are one classification of psychoactive drugs. Drugs in this category enhance alertness, wakefulness, and increase physical movement.

Caffeine

 Caffeine is usually ingested orally through coffee, tea, or caffeine pills. If it is taken orally, caffeine is subjected to first-pass metabolism, which means your body breaks down some of the drug before it is able to reach your circulatory system and brain.

At the neuronal level, caffeine blocks adenosine receptors. Adenosine dampens brain activity, and is associated with behavioural effects such as lethargy, fatigue, and decreased locomotion. By inhibiting adenosine from binding to its receptors, caffeine helps you stay aroused and alert. It can also increase the amount of serotonin in the brain, a neurotransmitter associated with elevated mood.

Other behavioural effects of caffeine, in moderate doses, are increased arousal, mood, energy, locomotion, and sociability. Furthermore, caffeine is widely accepted to have some beneficial effects such as decreased risk of cardiovascular disease, diabetes, and certain types of cancer. In higher doses, however, caffeine can lead to feelings of anxiety, panic, and irritability.

Believe or not, you can overdose from caffeine consumption. However, it would take roughly 80–100 cups of coffee, consumed in a relatively short time, to accomplish this.

Like any other drug, if you consume a lot of caffeine, you will develop a tolerance. Withdrawal symptoms will also occur if you are a regular latte sipper and you stop drinking coffee entirely; headache, lethargy, and fatigue are all common.

Cocaine

Cocaine comes from the coca plant native to South America. Recreational use of cocaine is usually administered through insufflation (snorting), or intravenously. Both routes of administration bypass first-pass metabolism, and quickly enter the brain.

When the neurons in your brain send neurotransmitters to communicate with other neurons, some of the remaining neurotransmitters are recycled and return to the neuron that released them; cocaine blocks this mechanism. Since the neurotransmitters that were released cannot go back into the cells that released them, they continue to stimulate adjacent neurons.

Cocaine acts on neurons that secrete dopamine, norepinephrine, and serotonin — all of which contribute to your arousal and mood.

In moderate doses, the behavioural and physiological effects of cocaine include increased energy, heart rate, self-esteem, talkativeness, and feelings of euphoria, but decreased appetite. In high doses, irritability, anxiety, hostility, aggression, and delusions of grandeur are often observed.

High doses of cocaine can often result in tachyarrhythmia (rapid irregular heartbeat), as well elevated blood pressure. Overdose from cocaine can lead to respiratory failure, stroke, heart failure, or cerebral hemorrhaging.

The body breaks down cocaine relatively quickly, and its effects are notoriously short-lived. This leads many individuals to administer additional doses, which can quickly lead to tolerance. Common cocaine withdrawal symptoms include lethargy, hypersomnia, dysphoria, and temporary depression.

Amphetimines

Amphetamine is a synthetic derivative of ephedrine, a stimulant used as a decongestant and appetite suppressant. The route of administration will vary with an amphetamine due to its chemical composition. When most hear the word amphetamine, they may attribute it solely to methamphetamine. However, methamphetamine is only one variation.

Although methamphetamine is usually inhaled through smoking, other forms such as dextroamphetamine and levoamphetamine, which are found in medications such as Adderall or Dexedrine, cannot be vaporized. Despite this, common routes of administration range from oral ingestion, intravenous, insufflation, and inhalation.

Like cocaine, an amphetamine will alter levels of serotonin, norepinephrine, and dopamine in the body’s nerve cells. After it has reached the brain, an amphetamine will enter nerve cells and displace neurotransmitters, forcing them out of the cell. The neurotransmitters then bind to other surrounding nerve cells, increasing levels of serotonin, norepinephrine, and dopamine — thus boosting arousal, locomotion, and mood.

In moderate doses, the behavioural and physiological effects of an amphetamine are similar to cocaine: increased alertness, heart rate, locomotion, talkativeness, restlessness, euphoria, along with a decrease in appetite, are all common effects. In high doses, irritability, anxiety, hostility, and aggression can be expected.

Common causes of death by amphetamine overdose are respiratory failure, cerebral hemorrhaging, circulatory collapse, and kidney failure. Withdrawal symptoms include fatigue, temporary depression, hypersomnia, increased appetite, and decreased movement.

Another classification of drugs are central nervous system depressants, or simply depressants. These drugs decrease wakefulness, alertness, and physical movement.

Alcohol

Ethyl alcohol is usually consumed in the form of beer, wine, or spirits. One very common misconception about alcohol is that different alcoholic beverages will give you different experiences while drunk — in truth, alcohol will do the same thing no matter what beverage it’s in. How much you drink, body composition, stomach contents prior to drinking, tolerance, and other factors will affect blood-alcohol content or ‘drunkenness,’ but whether you drink 40-proof tequila or 40-proof whiskey will not.

Consumed orally, alcohol is subject to first-pass metabolism and is broken down. After entering the brain, alcohol binds to specific receptors on nerve cells called GABA-A receptors. This allows specific ions to enter nerve cells, which decrease the ability of said nerve cells to send messages to adjacent neurons. The result is an overall decrease in brain activity.

In moderate doses, the behavioural and physiological effects of alcohol include decreased alertness, relaxed inhibitions, and some loss of motor coordination. In higher doses, effects include slurred speech, exaggerated emotions, severely impaired motor coordination, and loss of consciousness.

When an individual’s blood-alcohol concentration reaches 0.45, coma or death can occur. Death from alcohol overdose is a result of paralysis of the medulla oblongata, which controls and regulates breathing. At high enough doses, alcohol will inhibit the medulla oblongata entirely, resulting in asphyxiation.

Acute withdrawal symptoms, such as those you might feel after a night of heavy drinking, include an inability to sleep, headache, cold and hot flashes, nausea and vomiting, and a feeling of restlessness. Chronic withdrawal symptoms may include shaking, increased blood pressure and heart rate, seizures, and hallucinations. In the case of some chronic alcoholics, withdrawal can even lead to death.

There are a number of problems associated with chronic alcohol consumption, such as liver damage, coronary heart disease, cancer, stroke, and brain damage. However, despite chronic effects, moderate alcohol use — alongside good nutrition and regular physical activity — is associated with some health benefits such as a decrease in cardiovascular disease.

Heroin

Heroin is a derivative of morphine, and both come from the opium poppy. Interestingly, differences between heroin and morphine are almost nonexistent — heroin is basically morphine with two acetyl groups added to it.

This difference allows heroin to enter your brain more quickly. But once the drug does enter your brain, the acetyl groups are cleaved and the molecular structure becomes identical to morphine. Common routes of administration for heroin are intravenous, insufflation, and inhalation. All of these routes quickly deliver the drug to the brain.

Heroin acts on the brain’s opioid receptors, which are distributed in different areas of the brain. Heroin’s effects on neurons will vary depending on which type of receptor is located in a particular neuron. No matter what, though, heroin always decreases neural communication. This is reflected in its depressive physiological and behavioural outputs.

A moderate dose of heroin will induce euphoria, shallow breathing, pupil constriction, constipation, decreased sex drive, and muscular weakness. At high doses, heroin’s effect on opioid receptors in the medulla oblongata can shut down respiratory function entirely, leading to a likely death.

Some of the withdrawal effects of heroin include dysphoria, irritability, pain, hyperthermia, diarrhea, restlessness, insomnia, and — if you have a penis — spontaneous ejaculation.

Marijuana

Marijuana does not fit perfectly into the classification of depressants, as some of the effects of marijuana can include small amounts of stimulation. Hallucinations can even occur at extremely high doses.

Marijuana is most often burned, and its smoke inhaled into the lungs. This route of administration results in the drug contained in the plant, THC, entering the circulatory system very quickly. However, THC in marijuana can also be infused into edibles such as cookies or brownies. If consumed this way, the effect of THC has a slower onset, but the duration of the drug’s effect will be much longer than inhalation.

The psychoactive compound in marijuana, THC, binds to cannabinoid receptors in the central and peripheral nervous system. There, it induces a sequence of actions which inhibit a neuron’s ability to send neurotransmitters to adjacent neurons. As a result, there is a minor decrease in neural communication.

In a moderate dose, some of the effects of THC include euphoria, muscle relaxation, dry mouth, red eyes, increased appetite, and slight impairments in judgement and motor coordination. In higher doses, anxiety, paranoia, and hallucinations can occur.

Unlike many others on this list, THC does not have a significant effect on the brainstem, which controls vital bodily functions, such as respiration and heart rate. This means that respiratory failure, the most common cause of death due to drug overdose, cannot occur as a result of THC consumption.

Debunking drug myths with Dr. Jones

Most of us are familiar with the media image of drug addicts, namely the physical effects of drugs like meth and heroin. But are drugs the sole cause of physical deterioration in their users?

Not according to Dr. Bryan Jones, professor of psychopharmacology at SFU. He notes that “many of our images of the typical drug user and the images of physical deterioration associated with drug use are not actually due to the drugs’ physical effects. [. . .] Conditions like ‘meth-mouth,’ [for instance] in which adult methamphetamine users have decayed teeth and receding gums, are most likely due to lifestyle factors, such as lack of oral hygiene, decreased water intake, poor diet, and decreased sleep.

“People who use meth regularly as prescribed by their physician, such as children with ADHD, do not experience this condition.”

As for drugs as inevitably addictive substances, Dr.  Jones says, “There is no such thing as an inevitable addiction. The most addictive drug we know of is tobacco, and heroin is the most addictive of the illegal substances. However, according to the National Institutes of Health in the USA, about 23 per cent of people who use heroin become addicted to it, while approximately 20 per cent of prescription opiate users may have difficulties in stopping despite pain cessation.

“With methamphetamine, again using American data, less than 10 per cent of people using meth in their lifetime have done so in the last year — hardly the mark of an inevitably addicting drug.”

Dr. Jones also responded to the fear that the legalization of a drug might threaten national health. “While it is certainly possible that legality — or regulation of a drug, like we have with tobacco and alcohol — could increase overall rates of use, there is no evidence that it would increase addiction or deterioration,” he explains. “In fact, the opposite has been seen. Multiple studies have shown that when heroin addicts have been given access to pure heroin by their physicians, their physical health actually improves, as do their employment prospects.

“In countries where drugs have been regulated or decriminalized, rates of use have actually decreased.”