Psychopharmacology is the study of substances that influence mental states. Such agents induce changes in mood, sensation, thinking, or behavior, and may be derived from plants or other natural sources or chemically synthesized in a laboratory.
How Psychoactive Agents Work
Many drugs— including the SSRI antidepressants such as Prozac, and stimulant medications —work directly or indirectly by altering levels of neurotransmitters, the chemical messengers in the brain. They may activate or inhibit the release of various neurotransmitters or block their reuptake in the nervous system, which increases their availability and beefs up their signaling power.
Overactivity in brain signaling pathways regulated by the neurotransmitter dopamine is thought to be responsible for the hallucinations and delusions that are characteristic of psychosis. Antipsychotic agents generally target dopamine receptors to reduce activity of the neurotransmitter. Because dopamine levels influence multiple functions in the brain, antipsychotic drugs can have unwanted side effects, especially in slowing movement.
Although at first glance it may seem paradoxical that stimulants can dampen a disorder marked by hyperactivity, it is not contradictory at the pharmacologic level. The drugs act on the neurotransmitters dopamine and norepinephrine to make them more available. The increased neurotransmitter, in turn, bolsters communication with brain areas responsible for such executive functions as the regulation of attention.
Like all other drugs, psychoactive agents have side effects in addition to their beneficial effects. Such agents typically act on one or another neurotransmitter, but since each neurotransmitter system influences many functions, the drugs can have an array of unwanted effects, from dry mouth with antidepressants to metabolic disturbances with antipsychotics. Treatment is best overseen by physicians with expertise in balancing the risks and benefits of each medication.
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