Psychoactive Drugs

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  • 0:43 Stimulants
  • 1:07 Depressants
  • 1:39 Narcotics
  • 1:56 Hallucinogens
  • 2:50 Tolerance and Addiction
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Lesson Transcript
Instructor: Polly Peterson
How do psychoactive drugs alter cognitive states? In this lesson, you'll learn how these chemical compounds affect neurotransmitter functions as well as explore some factors that can affect the outcomes of drug use.

As their name suggests, psychoactive drugs affect psychological experiences by altering your sensory perception, moods, thinking and behavior. Psychoactive drugs have these effects because they impact neurotransmitter function. Neurotransmitters are the chemical signals that affect how hungry, thirsty, anxious, scared, happy or tired you are.

There are four main types of psychoactive drugs:

  • Stimulants
  • Depressants
  • Narcotics
  • Hallucinogens

Stimulants range from nicotine and caffeine to cocaine and crystal meth. Stimulants block the reuptake or reabsorption of neurotransmitters like serotonin and dopamine, which can lead to increased energy, panic and anxiety. Think about how coffee or cigarettes can make you jittery.

On the other hand, depressants increase the production of the neurotransmitter GABA, which decreases reactions in the brain. Depressants, like alcohol, cause slowed reactions, impaired speech and drowsiness. Depressants affect cognition by impairing memory. Depressants like benzodiazepines help GABA neurotransmitters bind to receptors that receive the chemical signals, leading to reduced nervous system activity and inducing sleep.

A third type of psychoactive drugs includes narcotics like morphine, heroin and codeine. Narcotics may be administered as painkillers for medical reasons, or used recreationally to create a sense of euphoria. They simulate your endorphins, which are neurotransmitters that naturally reduce pain.

Hallucinogens include LSD, mescaline and ecstasy. These drugs mimic the effects of the neurotransmitters serotonin and epinephrine, which lessen pain. They can also trick the brain into seeing or hearing things that aren't actually there, warping a person's sense of time and space. These altered states of consciousness can lead to paranoia and anxiety.

Some researchers put cannabis in a fifth category, since marijuana and hashish have effects similar to both narcotics and hallucinogens.

Your nervous system will try to rebalance when your neurotransmitter levels are increased or decreased in the presence of psychoactive drugs. You could become drug-tolerant if your receptors are overstimulated from prolonged drug use, resulting in fewer or less sensitive receptors. Tolerance can lead to addiction, or system dependence, since more and more of a drug is needed to achieve the original effect in a less sensitive system.

Long-term drug use affects the body, so some drugs produce withdrawal symptoms when you quit. Not all drugs are physically addictive, though many are psychologically addictive. The prevailing theory on marijuana seems to be that it's more psychologically addictive than physically addictive. People become physically addicted when they're trying to avoid withdrawal symptoms. Withdrawal is no joke; you can actually die from the withdrawal symptoms of some drugs, which is why severe addicts must be monitored and sometimes given low doses of a drug or a substitute drug to counteract the negative effects. Heroin addicts may be given the synthetic drug methadone to wean them off heroin, which is a more potent narcotic.

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