Psychoactive, psychotropic or mind-altering drugs change behavior by acting on the central nervous system, or CNS, which includes the brain and spinal cord. Psychopharmacology is the study of how psychoactive drugs affect the brain and behavior. Many classes of drugs have unique effects on the brain and behavior, such as sedatives, opiates, stimulants and hallucinogens.
Sedatives
Sedatives, usually collectively termed barbiturates, are drugs that produce calming effects. The calming effects of sedatives include a reduced motor activity and at higher doses, drowsiness and sleep. Some barbiturates function as anesthetics to induce sleep and insensitivity to pain. Barbiturates usually taken orally in the form of tablets or pills and have been referred to as “solid alcohols” because they exhibit alcohol-like effects: disinhibition, loss of motor control, sleep, anesthesia, coma, sedation and sometimes death. In the CNS, barbiturates are not very selective, and they depress all excitable nervous tissue. In the brain, barbiturates depress parts of the forebrain and brain stem, resulting in blocked arousal. Barbiturates are highly addictive and have severe withdrawal symptoms for those trying to overcome an addiction.
Stimulants
Stimulants are a group of drugs that excite the central nervous system by stimulating behavior, inducing euphoria, easing depression, increasing alertness, diminishing appetite and relieving fatigue. Amphetamines are prototypical stimulants and can be taken orally or intravenously. Amphetamines block the reuptake of catecholamines--neurotransmitters that have varying effects, including arousal and cause the release of newly synthesized dopamine, according to "Drugs, Brains, and Behavior." In the brain, the reward effects of amphetamines--at high intravenous doses described as an "orgasmic rush"--of these types of drugs are associated the basal ganglia and brain stem, according to "Drugs and Human Behavior." The euphoria resulting from amphetamines shows tolerance, requiring increasing doses for continued effect.
Opiates
Opiates are drugs that induce euphoria and pain relief. Opiates include opium, morphine, heroin, synthetic painkillers and codeine. Opiates can be taken orally, by injection or by sniffing or smoking, depending on the drug. Morphine is the hallmark opiate, being the main active ingredient of opium and the main active metabolite of heroin. Changes in mood are the result of their action on the limbic system in the brain, states "Drugs and Human Behavior." Morphine actually alters the emotional response to pain. Intravenous administration of morphine or heroine results in a rush that is often described as a wave of pleasure that can last for five minutes or more, followed by a period of tranquility. Opiate addiction is usually caused by the loss of euphoria and severe withdrawal symptoms.
Hallucinogens
Hallucinogens are drugs that can produce hallucinations, cause states resembling delirium and disturb cognition and perception. LSD or lysergic acid diethylamide is one of the most well known hallucinogens. LSD is usually taken orally, and the onset of action occurs after 30 to 90 minutes, with a duration of 5 to 12 hours. Within the brain, the pattern of LSD distribution is greatest in visual areas, parts of the limbic system and the reticular formation of the brain stem. The LSD experience is known as a “trip,” which can include intense emotions, abnormal color perception, space and time distortions, strange body perceptions and visual hallucinations. Additionally, colors may be heard and sounds experienced as light or form.
References
- "Drugs, Brains and Behavior"; C. Robin Timmons & Leonard W. Hamilton
- "Drugs and Human Behavior"; Tibor Palfai and Henry Jankiewicz; 1997
