Introduction to Psychology 1/IPSY103/Substance use and abuse/Drug categories

The effects of all psychoactive drugs occur through their interactions with our endogenous neurotransmitter systems. The four major drug categories and their relationships, are shown in the Figure below. As you have learned, drugs can act as agonists or antagonists of a given neurotransmitter system. An agonist facilitates the activity of a neurotransmitter system, and antagonists impede neurotransmitter activity.