Drug Facts

Drug Facts: How Do They Affect the Brain

Bath Salts

The lab-made cathinones in “bath salts” can temporarily produce feelings of joy and increased social interaction, including an increased sex drive. But they can also cause paranoia, nervousness, and hallucinations (seeing or hearing things that are not real).

There is a lot we still don’t know about how the different chemicals in "bath salts" affect the brain. Researchers do know that bath salts are chemically similar to amphetamines, cocaine, and MDMA. Therefore, some of the effects of “bath salts"—such as feeling energetic and agitated—are similar.

These drugs change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters. Drugs affect this signaling process. 

“Bath salts” raise the level of one type of neurotransmitter, called dopamine, in brain circuits that control reward and movement. Dopamine is the main neurotransmitter that relates to the brain's reward systemthe system that tells us we feel good. Circuits in the reward system use dopamine to teach the brain to repeat actions we find pleasurable. Drugs take control of this system, releasing large amounts of dopaminefirst in response to the drug but later mainly in response to other cues associated with the drug, like when you see people you use drugs with, or plases where you use drugs. The result is an intensive motivation to seek the drug.

Additionally, the hallucinations often reported by people who use “bath salts” are similar to the effects caused by other drugs such as MDMA or LSD. These drugs raise levels of the neurotransmitter serotonin.

Learn more about how the brain works and what happens when a person uses drugs. And, check out how the brain responds to natural rewards and to drugs.

Cocaine

All drugs change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters. These neurotransmitters attach to molecules on neurons called receptors. (Learn more about how neurotransmitters work.) Drugs affect this signaling process.

There are many neurotransmitters, but dopamine is the main one that makes people feel good when they do something they enjoy, like eating a piece of chocolate cake or playing a video game. Normally, dopamine gets recycled back into the cell that released it, thus shutting off the signal. Stimulants like cocaine prevent the dopamine from being recycled, causing a buildup of the neurotransmitter in the brain. It is this flood of dopamine that reinforces taking cocaine, “training” the brain to repeat the behavior.  The drug can cause a feeling of intense pleasure and increased energy.

With repeated use, stimulants like cocaine can disrupt how the brain’s dopamine system works, reducing a person’s ability to feel pleasure from normal, everyday activities. People will often develop tolerance, which means they must take more of the drug to get the desired effect. If a person becomes addicted, they might take the drug just to feel “normal.”

After the "high" of the cocaine wears off, many people experience a "crash" and feel tired or sad for days. They also experience a strong craving to take cocaine again to try to feel better.

Learn more about how the brain works and what happens when a person uses drugs. And, check out how the brain responds to natural rewards and to drugs.

Cough and Cold Medicine (DXM and Codeine Syrup)

When cough and cold medicines are taken as directed, they safely treat symptoms caused by colds and flu. But when taken in higher quantities or when you don't have any symptoms, they may affect the brain in ways very similar to illegal drugs, and can even lead to addiction. 

All drugs, including cough and cold medicines, change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters. These neurotransmitters attach to molecules on neurons called receptors. Drugs affect this signaling process. (Learn more about how neurotransmitters work.)

DXM acts on the same brain cell receptors as hallucinogenic drugs like ketamine or PCP. A single high dose of DXM can cause hallucinations (imagined experiences that seem real). Ketamine and PCP are called "dissociative" drugs, which means they make you feel separated from your body or your environment, and they twist the way you think or feel about something or someone.

Codeine attaches to the same cell receptors as opioids like heroin. High doses of promethazine-codeine cough syrup can produce a high similar to that produced by other opioid drugs. Over time, it takes more and more of the drug to get that good feeling. This is how addiction starts. 

Both codeine and promethazine slow down activities in the central nervous system (brain and spinal cord), which produces calming effects.

Learn more about how the brain works and what happens when a person uses drugs.

Heroin

When heroin enters the brain, it attaches to molecules on cells known as opioid receptors. These receptors are located in many areas of the brain and body, especially areas involved in the perception of pain and pleasure, as well as a part of the brain that regulates breathing.

Short-term effects of heroin include a rush of good feelings and clouded thinking. These effects can last for a few hours, and during this time people feel drowsy, and their heart rate and breathing slow down. When the drug wears off, people experience a depressed mood and often crave the drug to regain the good feelings.

Regular heroin use changes the functioning of the brain. Using heroin repeatedly can result in:

  • tolerance: more of the drug is needed to achieve the same “high”
  • dependence: the need to continue use of the drug to avoid withdrawal symptoms
  • addiction: a devastating brain disease where, without proper treatment, people have trouble stopping using drugs even when they really want to and even after it causes terrible consequences to their health and other parts of their lives. Because of changes to how the brain functions after repeated drug use, people that are addicted crave the drug just to feel “normal.”

Learn more about how the brain works and what happens when a person uses drugs. And, check out how the brain responds to natural rewards and to drugs.

Inhalants

The lungs absorb inhaled chemicals into the bloodstream very quickly, sending them throughout the brain and body. Nearly all inhalants (except nitrites) produce a "high" by slowing down brain activity. Nitrites, in contrast, expand and relax blood vessels.

Many brain systems may be involved in producing effects of different inhalants. Knowing how the brain functions helps us understand what happens during drug use. 

Inhalants often contain more than one chemical. Some chemicals leave the body quickly, but others stay for a long time and get absorbed by fatty tissues in the brain and central nervous system. Over the long term, the chemicals can cause serious problems:

  • Damage to nerve fibers. Long-term inhalant use can break down the protective sheath around certain nerve fibers in the brain and elsewhere in the body. This hurts the ability of nerve cells to send messages, which can cause muscle spasms and tremors or even permanent trouble with basic actions like walking, bending, and talking. These effects are similar to what happens to people with the disease multiple sclerosis.
  • Damage to brain cells. Inhalants also can damage brain cells by preventing them from getting enough oxygen. The effects of this condition, also known as brain hypoxia, depend on the area of the brain that gets damaged. The hippocampus, for example, is responsible for memory, so someone who repeatedly uses inhalants may be unable to learn new things or may have a hard time carrying on simple conversations. If the cerebral cortex is damaged, it will affect a person's ability to solve complex problems and plan ahead. And, if the cerebellum is affected, it can cause a person to move slowly or be clumsy.

Learn more about how the brain works and what happens when a person uses drugs.

Marijuana

All drugs change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters. These neurotransmitters attach to molecules on neurons called receptors. (Learn more about how neurotransmitters work.) Drugs affect this signaling process.

When marijuana is smoked or vaporized, THC quickly passes from the lungs into the bloodstream, which carries it to organs throughout the body, including the brain. Its effects begin almost immediately and can last from 1 to 3 hours. This can affect decision making, concentration, and memory for days after use, especially in people who use marijuana regularly.1 If marijuana is consumed in foods or beverages, the effects of THC appear later—usually in 30 minutes to 1 hour—and may last for many hours. Some people consume more and more waiting for the “high” and end up in the emergency room with uncomfortable symptoms from too much THC.

As it enters the brain, THC attaches to cells, or neurons, with specific kinds of receptors called cannabinoid receptors. Normally, these receptors are activated by chemicals similar to THC that occur naturally in the body. They are part of a communication network in the brain called the endocannabinoid system. This system is important in normal brain development and function.

Marijuana's Effects on the Brain

Most of the cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thinking, concentration, sensory and time perception, and coordinated movement. Marijuana activates the endocannabinoid system, which causes the "high" and stimulates the release of dopamine in the brain's reward centers, reinforcing the behavior. Other effects include changes in perceptions and mood, lack of coordination, difficulty with thinking and problem solving, and disrupted learning and memory.

Learn more about how the brain works and what happens when a person uses drugs.

1 Crean RD, Crane NA, Mason BJ. An evidence based review of acute and long-term effects of cannabis use on executive cognitive functions. Journal of Addiction Medicine 2011;5:1-8.

MDMA (Ecstasy or Molly)

Once an MDMA pill or capsule is swallowed, it takes about 15 minutes for the drug to enter the bloodstream and reach the brain. MDMA produces its effects by increasing the activity of three neurotransmitters (the chemical messengers of brain cells): serotonin, dopamine, and norepinephrine. Let's take a look at the importance of these chemicals: 

  • Serotonin—plays a role in controlling our mood, aggression, sexual activity, sleep, and feelings of pain. The extra serotonin that is released by MDMA likely causes mood-lifting effects in users. People who use MDMA might feel very alert, or “hyper,” at first. Some experience altered sense of time and other changes in perception, such as a more intense sense of touch. Serotonin also triggers the release of the hormones oxytocin and vasopressin, which play a role in feelings of love, sexual arousal, and trust. This may be why users report feeling a heightened sense of emotional closeness and empathy. 
  • Dopamine—helps to control movement, motivation, emotions, and sensations like pleasure. The extra dopamine is linked to continued cravings for the drug.
  • Norepinephrine—increases heart rate and blood pressure, which are particularly risky for people who have problems with their heart and blood circulation.

Because MDMA increases the activity of these chemicals, some users experience negative effects. They may become anxious and agitated, become sweaty, have chills, or feel faint or dizzy.

Even those who don’t feel negative effects during use can experience bad after-effects. Even weeks later, people can experience confusion, depression, sleep problems, drug craving, and anxiety, because the surge of serotonin caused by MDMA reduces the brain's supply of this important chemical.

Learn more about how the brain works and what happens when a person uses drugs. And, check out how the brain responds to natural rewards and to drugs.

Methamphetamine (Meth)

All drugs change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters, telling us how to act and behave. These neurotransmitters attach to molecules on neurons called receptors. (Learn more about how neurotransmitters work.)

There are many neurotransmitters, but dopamine is the one that reinforces cravings for pleasurable behaviors,  like eating a piece of chocolate cake or playing a video game. With repeated use, stimulants like methamphetamine can disrupt how the brain’s dopamine system works, reducing a person’s ability to feel pleasure from normal, everyday activities. People will often develop tolerance, which means they must take more of the drug to get the desired effect. If a person becomes addicted, they might take the drug just to feel “normal.”

After the "high" of methamphetamine wears off, many people experience a "crash" and feel tired or sad for days. They also experience a strong craving to take methamphetamine again to try to feel better.

Learn more about how the brain works and what happens when a person uses drugs.

Prescription Depressant Medications

Most depressants affect the brain by increasing the activity of gamma-aminobutyric acid (GABA), a chemical in the brain that sends messages between cells. The increased GABA activity in turn slows down brain activity. This causes a relaxing effect that is helpful to people with anxiety or sleep problems. Too much GABA activity, though, can be harmful.

Learn more about how the brain works and what happens when a person misuses drugs.

Prescription Drugs

In the brain, neurotransmitters such as dopamine send messages by attaching to receptors on nearby cells. The actions of these neurotransmitters and receptors cause the effects from prescription drugs. Each class of prescription drugs works a bit differently in the brain:

  • Prescription opioid pain medications bind to molecules on cells known as opioid receptors—the same receptors that respond to heroin. These receptors are found on nerve cells in many areas of the brain and body, especially in brain areas involved in the perception of pain and pleasure.
  • Prescription stimulants, such as Ritalin, have similar effects to cocaine, by causing a buildup of the brain chemicals dopamine and norepinephrine.
  • Prescription depressants make a person feel calm and relaxed in the same manner as the club drugs GHB and rohypnol.

Learn more about how the brain works and what happens when a person misuses drugs.

Prescription Pain Medications (Opioids)

Opioids attach to specific proteins, called opioid receptors, on nerve cells in the brain, spinal cord, gut, and other organs. When these drugs attach to their receptors, they block pain messages sent from the body through the spinal cord to the brain. They can also reduce or stop other essential functions like breathing.

Opioid receptors are also located in the brain’s reward center, where they cause a large release of the neurotransmitter dopamine. This causes a strong feeling of relaxation and euphoria (extreme good feelings). Repeated surges of dopamine in the reward center from drug-taking can lead to addiction.

Learn more about how the brain works and what happens when a person misuses drugs. And, check out how the brain responds to natural rewards and to drugs.

Prescription Stimulant Medications (Amphetamines)

The brain is made up of nerve cells that send messages to each other by releasing chemicals called neurotransmitters. Common stimulants, such as amphetamines and methylphenidate, have chemical structures that are similar to certain key brain neurotransmitters including dopamine and norepinephrine. Stimulants boost the effects of these chemicals in the brain and body.

When doctors prescribe stimulants for a medical condition, they start with low doses and increase them slowly until they find the dose that works best. However, when taken in amounts or ways other than prescribed, like snorting or injecting, stimulants can increase the dopamine in the brain very quickly. This changes the normal communication between brain cells, producing a ‘high’ while also increasing the risk for dangerous side effects. Over time, this can lead to addiction, which is when you continue to use the drug despite negative consequences. 

Learn more about how the brain works and what happens when a person miuses drugs.

Salvia

Researchers are studying salvia to learn exactly how it acts in the brain to produce its effects. What is currently known is that salvinorin A, the main active ingredient in salvia, attaches to parts of nerve cells called kappa opioid receptors. (Note: These receptors are different from the ones involved with opioid drugs, such as heroin and morphine.)

The effects of salvinorin A are described as intense but short lived, generally lasting for less than 30 minutes. People who use salvia generally have hallucinations—they see or feel things that aren’t really there. They also have changes in vision, mood and body sensations, emotional swings, and feelings of detachment (disconnected from their environment). There are reports of people losing contact with reality—being unable to tell the difference between what’s real and what’s not. Many of these effects raise concern about the dangers of driving under the influence of salvia.

Learn more about how the brain works and what happens when a person uses drugs.

Spice

Some Spice users report extreme anxiety, feeling like someone is out to get them (paranoia), and seeing or hearing things that aren’t there (hallucinations). They also sometimes report feeling relaxed and having only mild changes in perception. 

Spice has only been around a few years, and research is only just beginning to measure how it affects the brain. What is known is that the chemicals found in Spice attach to the same nerve cell receptors as THC, the main mind-altering ingredient in marijuana. Some of the chemicals in Spice, however, attach to those receptors more strongly than THC, which could lead to a much stronger and more unpredictable effect. Additionally, there are many chemicals that remain unidentified in products sold as Spice and it is therefore not clear how they may affect the user. Moreover, these chemicals are often being changed as the makers of Spice alter them to avoid the products being illegal.

Learn more about how the brain works and what happens when a person uses drugs.

Steroids, Anabolic

Anabolic steroids affect a part of the brain called the limbic system, which controls mood. They don’t cause a “high” like some other drugs, but can cause harmful effects.

Long-term steroid misuse can lead to aggressive behavior and extreme mood swings. This is sometimes referred to as “roid rage.” It can also lead to feeling paranoid (like someone or something is out to get you), jealous, delusional (believing in something that is not true), and invincible (like nothing can hurt you).

Learn more about how the brain works and what happens when a person uses drugs.