Chapter 1: An Introduction to Psychoactive Drugs

By the end of this chapter, you should be able to:

  • Examine the dominant beliefs and attitudes in our society with regard to chemical use, abuse, and addiction. (LO1)
  • Define the characteristics of the major classes of drugs. (LO2)

Characteristics of Psychoactive Drugs

Drug use disorders are addictive disorders, defined within the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). This is used to diagnose all patients with psychological disorders. Individuals who are diagnosed with substance abuse disorders often exhibit both physical and psychological dependence. involves a change in normal bodily function; the user will also experience as they eliminate the drugs from their system. Withdrawal symptoms, when abstaining, may have the opposite effects of the drug’s action when it is used. is an emotional, rather than physical need, for the drug, because drug use may relieve some psychological distress. Another term to recognize is tolerance. is related to physical dependence; when a person requires more and more of a drug in order to experience the desired effects; a frequent side effect of long term drug use.

Psychoactive drugs affect our endogenous neurotransmitter systems. Drugs can act as agonists or antagonists of a given neurotransmitter system (Baker, 2022). Agonists facilitate the activity of a neurotransmitter system, while antagonists impede neurotransmitter activity. The main categories of drugs are , , and ; others include opiates and hallucinogens. These will be covered below.

Drug Categories

The classification of psychoactive drugs is limited to their molecular structure. Each drug reacts in a unique way with neurotransmitters; some drugs react with more than one transmitter. Acetylcholine is the most prominent neurotransmitter effected by drug use (and abuse), but there are many others like dopamine, adenosine, serotonin, and more. Drugs change the way the brain works, disrupting how nerve cells (neurotransmitters) send, receive, and process information. Drugs have the ability to imitate the brain’s natural messengers and overly reinforce positive reactions. The drugs accomplish this by crossing the blood brain barrier (Lumen). The (National Cancer Institute, 2022), typically prevents toxic substances from entering our brains, but because drugs bear a similar molecular structure as our neurotransmitters, they are able to slip through the barrier unnoticed. Psychoactive drugs actually promote equilibrium in our brains, specifically the CNS.  Drugs imitate so many of our natural processes to the point that even brain scans cannot accurately identify drug cravings (Inaba, 2011). The brain actively works to return to equilibrium, this is the process of withdrawal. Cocaine, for example, stimulates feel good chemicals. For an addict, when the use stops, there may be six months of depression before the brain is able to return to a normal balance. Some individuals may be prescribed medications to simulate these feel good chemicals, like serotonin.

There are instances however, when the drugs being used can completely shut down a person’s system, resulting in unexpected death. For example, if a person with drug sensitivity uses cocaine, electrical signals from the brain to the heart cease to occur and the person dies. An individual’s brain chemistry is unique, so it will determine how sensitive a person is to environmental stressors, drugs, and inheritable characteristics (SAMHSA, 2022).

Review the table below, selecting the hot spots for additional content. Select the icon in the upper right corner of the graphic to expand it to full screen.



Beliefs and Attitudes Related to Drugs

Drug addiction is a serious psychological disorder, as shown above, it actually affects brain chemistry. There is no perfect solution to end addiction (Daniewicz, 2014). Review some of the myths of addiction, shared below. Track how many of these myths you have believed at some point. Reflect on whether you still feel that way now. These myths are from Face it Together (2022), an organization committed to helping those struggling with addiction. You can select the double pointed arrow in the lower right corner to make the slides full screen.



Throughout history, most if not all cultures have been attracted to substances that alter their brain chemistry (Lumen). And historically, governments financially exploit the use of psychoactive drugs to produce revenue. Even in recent studies, there is still a positive attitude regarding alcohol in emerging adults. Below are some statistics, related to the alcohol, tobacco and other drugs, provided by the Substance Abuse and Mental Health Services Administration (2020 data).

  • Approximately 19.3 million people, 18 years of age or order, have had a substance abuse in the last year.
  • In 2020, approximately 14.5 million people age 12 or older had an alcohol use disorder.
  • In 2020, 57.3 million people age 12 or older use nicotine products.
  • In 2020, 9.5 million people misused opioids in the next year.
  • In 2019, 48.2 million people used marijuana in the last year.
  • In 2019, 2 million people used methamphetamine in the last year, and over half have a meth use disorder.
  • In 2019, 5.5 million people have used cocaine and nearly a million use crack.

Review the following TED Talks related to addiction, to better understand the attitudes and beliefs in society related to addiction.



Baker, J. (2022). Disease prevention and healthy lifestyles. Course Hero. Retrieved June 16, 2022 from

Ball, E. (2020, October 26). Changing the stigma of mental health and addiction [Video]. YouTube.

Daniewicz, S. (2014). Attitudes toward drug use and alcohol use: Culture and emerging adulthood. Undergraduate Research Symposium. 4.

Face It Together (2022). Common myths about addiction. Face It Together. Retrieved June 16, 2022 from

Grisel, J. (2020, February 4). Never enough: The neuroscience and experience of addiction [Video]. YouTube.

Hari, J. (2015, July 9). Everything you think about addiction is wrong [Video]. YouTube.

Hart, C. (2015, May 19). Let’s quit abusing drug users [Video]. YouTube.

Inaba, D. (2011). Uppers, downers, all arounders: Physical and mental effects of psychoactive drugs. CNS Productions.

Khan Academy. (2015, July 15). Overview of psychoactive drugs [Video]. YouTube.

Khan Academy (2014, June 25). Psychoactive drugs: Depressants and opiates [Video]. YouTube.

Khan Academy (2014, June 25). Psychoactive drugs: Hallucinogens [Video]. YouTube.

Khan Academy. (2014, June 24). Psychoactive drugs: Stimulants [Video]. YouTube.

Lumen Learning (n.d.). Introduction to psychology. Lumen Learning. Retrieved June 15, 2022 from

National Cancer Institute (2022). Dictionary of cancer terms. National Cancer Institute. Retrieved June 16, 2022.

OpenStax and Lumen Learning (n.d.). General psychology. University of Central Florida. Retrieved June 15, 2022 from

Psychoactive Drugs (2022, June 15). Psychoactive drug. Wikipedia. Retrieved June 15, 2022 from

Substance Abuse and Mental Health Services Administration (2022). Alcohol, tobacco, and other drugs. SAMHSA. Retrieved June 16, 2022 from


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Psychology of Addiction by Andrea Bearman and Adelle Schwan is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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