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Summary: Psychoactive Drugs

Psychoactive drugs are those that affect states of consciousness. They come in several varieties. Stimulants increase activity. Depressants reduce activity. Opiates kill pain, unless they are used for a long period of time. Then they can increase sensitivity to pain.

Hallucinogens produce a state resem­bling a waking dream. Hypnotics alter perception and thinking without the dramatic changes of hallucinogens. Marijuana is in a category by itself, with regard to its chemical action. It engages a transmitter system in the forebrain.

The most commonly used depressant drug is alcohol. Researchers describe the characteristic mental state produced by alcohol as "alcohol myopia." Attention to long-term plans and problems is reduced, while attention to immediate events and stimulation is increased.

Stimulant drugs include amphet­amines, cocaine, and caffeine. Cocaine can cause sudden heart attacks because it reduces activity in the vagus nerve, which normally lowers the heart rate as blood pressure rises. Behaviorally, both cocaine and methamphetamine mimic the natural effects of stress, causing increases in aggression and sexual activity.

Opiates are drugs such as heroin and morphine, similar to the endorphins, natural pain-killing drugs in the body. The word opioid originally referred to synthetic versions of opiate drugs but is now used to refer to all opiate-like drugs.

Nitrous oxide, a gas used as an anes­thetic by some dentists, produces a cross-tolerance to opioids. Therefore it must affect the same neurotransmitters.

Marijuana does not fit easily into other drug classifications. Its chemical action is unique, affecting mostly the cerebral cortex and hippocampus of the brain. Chemicals that block cannabinoid receptors may eventually prove useful as anti-obesity drugs.

Psychedelics such as LSD produce dramatic, dream-like experiences while awake. Albert Hoffman discovered LSD accidentally and discovered its effects.

Hoffman followed this up with an intentional test. He experienced a disorienting trip that left him thinking the drug would have little abuse potential but might be interesting to psychiatrists.

MDMA (ecstasy) has become a popular recreational drug. Users often report that it makes them feel like they "love everybody."

MDMA has a dose/toxicity ratio less dangerous than that of alcohol, but it kills people by increasing the likelihood of hyperthermia (dangerously high body temperature). That is especially likely when MDMA is combined with other drugs like alcohol.


Write to Dr. Dewey at psywww@gmail.com.


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