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  • APSI


In the context of substance use prevention, we are looking at a broad range of psychoactive substances including tobacco, alcohol, cannabis, certain prescription medications, heroin, methamphetamine, inhalants, and designer drugs that appear and disappear from use at various times.

The field of Psychoactive Substance Use has moved away from using terms such as ‘drugs’, or ‘legal’ vs. ‘illegal’. Instead, the focus is on a class of substances that create changes in our central nervous system (CNS), affecting feelings, perceptions, thought processes, and/or behavior. These substances, overall, are termed psychoactive substances.  However, for practicality purposes, reference is made to Psychoactive Substance Use and with progression to Psychoactive Substance Use Disorders that include social and emotional problems in addition to dependence.

There are four main classes, or types, of psychoactive substances: 

  • Stimulants

  • Opioids (sometimes called narcotics)

  • Depressants

  • Hallucinogens

These classes are based on the substance’s primary effects on the CNS:

  • Stimulants increase the activity of the CNS. They tend to increase heart rate and breathing and offer a sense of excited euphoria.

  • Opioids selectively depress the CNS. These analgesics reduce pain and tend to induce sleep. Depressants decrease the activity of the CNS. They tend to decrease heart rate and breathing and offer a relaxed, sometimes sleepy, sense of well-being or euphoria.

  • Hallucinogens produce a spectrum of vivid sensory distortions and markedly alter mood and thinking. 

Although the classification system generally includes most psychoactive substances, there are many that do not fit neatly into the basic categories. Some have multiple effects at different dose levels.

For example:

  • Marijuana may be somewhat sedating or relaxing in low doses, but may have some hallucinogenic effects at high doses.

  • Miraa (khat) can induce mild euphoria and excitement at low doses, but at higher doses it can also induce manic behaviors and hyperactivity

  • Dissociative anesthetics can have hallucinogenic effects, but can also have depressant or stimulant effects

  • Inhalants generally have depressant effects, but can also have stimulant or hallucinogenic effects.

Prevention professionals need to understand how psychoactive substances operate in the human brain, particularly the developing brains of children and adolescents, which can put their health at risk.  But, also important is the role of prevention professionals as often the “expert in the room” who answers the questions of those we serve.

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