What are psychoactive drugs?

• A. Drugs that cure infections
• B. Drugs that alter metabolic rate only
• C. Drugs that influence subjective experience and behavior by acting on the nervous system
• D. Drugs that have no effect on the brain

Answer: (C)

Psychoactive drugs are substances that influence subjective experience and behavior by acting on the nervous system. They change brain signaling—through receptors and neurotransmitter systems—leading to altered mood, perception, thoughts, or actions. That’s why they’re described as affecting how we feel and behave, because their primary action is on brain function. The other ideas miss this core feature: drugs that cure infections don’t primarily alter brain activity, changing metabolic rate isn’t what defines psychoactivity, and a substance with no brain effect wouldn’t be considered psychoactive. Examples include caffeine, alcohol, cannabis, opioids, and psychedelics, all of which modify brain activity to produce their characteristic effects.