Psychoactive drugs are substances that can alter perception, mood, consciousness, cognition, or behavior by changing the brain's neurochemistry.
These are the body's natural chemicals that transmit signals across a synapse from one neuron (nerve cell) to another 'target' neuron.
These are a type of psychoactive drug that primarily cause hallucinations—perceptions that have no basis in reality.
This is another category of psychoactive drugs which increase activity in the central nervous system causing increased alertness and energy.