Psychoactive drugs refer to a broad category of substances that are capable of changing mood, behavior and perception. They alter the functioning of the brain by passing through what is known as the blood-brain barrier to affect the central nervous system. Psychoactive drugs can be divided into two broad types: those that are used for therapeutic purposes and those that are used for recreational purposes.
Also called psychotropic drugs, psychoactive drugs include medicines that are prescribed by medical professionals to treat ailments like insomnia, anxiety and depression. Psychoactive drugs commonly used in the treatment of insomnia and anxiety include benzodiazepines, which inhibit the central nervous system's function and cause sedation. Barbiturates, another type of psychoactive drug, are used for sedation and are sometimes employed as anesthetics. Both benzodiazepines and barbiturates are categorized as depressants, a classification that also includes alcohol.
Clinical depression is another ailment for which psychoactive drugs may be prescribed. One class of psychopharmaceutical drug often prescribed for depression is serotonin reuptake inhibitors. These include medications like sertraline. Another class of psychoactive drug used for treating depression is tricyclic antidepressants, such as amoxapine. Monoamine oxidase (MAO) inhibitors are also prescribed for depression.
Medications used to treat psychosis fall in the category of psychoactive drugs. Many of these medicines are classed as phenothiazines and work on a patient's brain to reduce such symptoms as delusional thinking and hallucinations. These psychopharmaceutical drugs are also referred to as antipsychotics and lessen psychotic symptoms by blocking dopamine receptors in the brain.
Some psychotropic drugs are categorized as stimulants because they stimulate the central nervous system. These include amphetamines, which are sometimes prescribed to aid weight loss. Nicotine, found in tobacco, is a stimulant, as is caffeine, which is present in coffee, soft drinks and chocolate. Other stimulants include illegal substances like cocaine and methamphetamine.
Stimulants available by prescription are often recommended by medical professionals to treat various physical and mental conditions. Psychoactive stimulants aid in the treatment of narcolepsy, a disease that causes a person to feel sleepy during the day and sometimes to unexpectedly fall asleep. Other stimulants are helpful in the management of attention deficit hyperactivity disorder (ADHD).
Another category of psychoactive drugs is the opiates, which affect the brain's opiate receptors. These medications are used as painkillers and include such drugs as heroin, methadone and morphine. Hallucinogenic drugs, also known as psychedelics, make up an additional category of psychoactive drugs. Psychedelics cause hallucinations and include such substances as lysergic acid diethylamide (LSD) and mescaline.