What is substance abuse disorder (drug addiction)?

Substance abuse disorder, or drug addiction, can be defined as a progressive disease that causes people to lose control of the use of some substance despite worsening consequences of that use. Substance use disorder can be life-threatening.

Addictions are not problems of willpower or morality. Addiction is a powerful and complex disease. People who have an addiction to drugs cannot simply quit, even if they want to. The drugs change the brain in a way that makes quitting physically and mentally difficult. Treating addiction often requires lifelong care and therapy.

What are drugs of abuse?

Drugs that are commonly misused include:

  • Alcohol.
  • Club drugs, like GHB, ketamine, MDMA (ecstasy/molly), flunitrazepam (Rohypnol®).
  • Stimulants, such as cocaine (including crack) and methamphetamine (meth).
  • Hallucinogens, including ayahuasca, D-lysergic acid diethylamide (LSD), peyote (mescaline), phencyclidine (PCP) and DMT.
  • Inhalants, including solvents, aerosol sprays, gases and nitrites (poppers).
  • Marijuana.
  • Opioid pain killers such as heroin, fentanyl, oxycodone, hydrocodone, codeine and morphine.
  • Prescription drugs and cold medicines.
  • Sedatives, hypnotics and anxiolytics (anti-anxiety medications).
  • Steroids (anabolic).
  • Synthetic cannabinoids (K2 or Spice).
  • Synthetic cathinones (bath salts).
  • Tobacco/nicotine and electronic cigarettes (e-cigarettes or vaping).

While these drugs are very different from each other, they all strongly activate the addiction center of the brain. That is what makes these substances habit-forming, while others are not.

Why do people with substance use disorder need more and more drugs over time?

People feel intoxicated after using drugs of abuse. Over time, the brain is changed by drugs of abuse. The brain becomes desensitized to the drug of abuse so that more of the drug must be used to produce the same effect.

As the person consumes more, drugs start to take over the person’s life. One may stop enjoying other aspects of life. For many people, social, family and work obligations fall to the side. The person with SUD starts to feel like something’s wrong if he or she isn’t under the influence of the substance. They may become consumed with the need to recapture that original feeling.

Who is at risk for substance use disorder?

Anyone can develop a substance use disorder. No one thing can predict whether a person may develop an addiction. You may be more prone to drug use due to:

  • Biology: The person’s genetic makeup, gender, ethnicity and mental health issues may raise his or her risk for developing an addiction. About two-thirds of people in addiction treatment are men. Particular ethnicities are at higher risk for substance abuse disorder. This is true for Native Americans.
  • Environment: Surroundings can affect the likelihood of developing substance use disorder. For example, stress, peer pressure, physical or sexual abuse and early exposure to drugs can raise the risk.
  • Age: Teenagers who start taking drugs are especially at risk. The parts of the brain that control judgment, decisions and self-control are not fully developed. Teens are more likely to engage in risky behaviors. In a developing brain, drugs can cause changes that make addiction more likely.

How common is substance use disorder?

Substance use disorder and alcohol use disorder are the leading causes of preventable illness and early death. Research has shown that about 1 in 9 Americans uses illicit drugs (about 11% of the population). The most commonly misused drugs are marijuana and prescription medications.

How might substance use disorder affect me?

Drugs affect the brain, especially the “reward center” of the brain.

Humans are biologically motivated to seek rewards. Often, these rewards come from healthy behaviors. When you spend time with a loved one or eat a delicious meal, your body releases a chemical called dopamine, which makes you feel pleasure. It becomes a cycle: You seek out these experiences because they reward you with good feelings.

Drugs of abuse send massive surges of dopamine through the brain, too. But instead of feeling motivated to do the things you need to survive (eat, work, spend time with loved ones), such massive dopamine levels can lead to damaging changes that change thoughts, feelings and behavior. That can create an unhealthy drive to seek pleasure from the drug and less from more healthy pleasurable experiences. The cycle revolves around seeking and consuming drugs to get that pleasurable feeling.

Addiction to drugs changes the brain over time. It affects how the brain works and even the brain’s structure. That’s why healthcare providers consider substance use disorder a brain disease.

The first use of a drug is a choice. But addiction can develop, creating a very dangerous condition. Drugs affect your decision-making ability, including the decision to stop drug use.

You may be aware there’s a problem but unable to stop. With addiction, stopping drug use can be physically uncomfortable. It can make you sick and even become life-threatening.

Why do people take drugs?

People may begin using drugs for several reasons. They may:

  • Enjoy the pleasurable experience.
  • Want to change or blunt their unpleasant feelings.
  • Want to improve their performance at work, school or athletics.
  • Be curious or give in to peer pressure.

What are symptoms of substance use disorder?

Symptoms of drug addiction include:

  • Bloodshot eyes and looking tired.
  • Changes in appetite, usually eating less.
  • Changes in physical appearance, such as having a poor complexion or looking ungroomed.
  • Craving drugs.
  • Difficulty completing tasks at work, school or home.
  • Engaging in risky behaviors, despite knowing negative consequences (such as driving while impaired or having unprotected sex).
  • Inability to reduce or control drug use.
  • Issues with money.
  • Weight loss.

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