Psychology MCAT Practice Exam 2025 – Complete All-in-One Guide to Ensure Your Success!

The correct class of consciousness-altering drugs that decreases brain activity and metabolism is indeed depressants. This category includes substances such as alcohol, benzodiazepines, and barbiturates, all of which function primarily by enhancing the effects of the neurotransmitter gamma-aminobutyric acid (GABA). By increasing GABA's inhibitory actions, depressants effectively lower neural excitability, resulting in a calming effect on the brain and body.

Different classes of substances affect the brain in various ways. Stimulants, for instance, increase alertness and arousal by boosting the activity of neurotransmitters like dopamine and norepinephrine, which leads to heightened brain activity rather than a decrease. Hallucinogens can produce altered perceptions and cognitive disruptions without necessarily reducing brain metabolism. Antidepressants primarily focus on correcting chemical imbalances associated with mood disorders and often work by modulating neurotransmitter systems to enhance mood and energy rather than suppressing brain activity.