Have you ever wondered how and why drugs affect the brain? This lesson goes over the basics of major drug classes and how they cause the central nervous system, namely the brain, to malfunction.

How Drugs Affect the Brain and Nervous System

The Effects of Drugs

A coffee gets you stimulated, alcohol makes you depressed. Why? It’s because of the way the drug interacts with your body. Some illicit drugs people take make them slow, others make them hyper. Some do crazy things like cause hallucinations. Do you know why these drugs do the things they do? It’s because of the way they interact with the central nervous system, namely the brain. Let’s briefly go over how drugs affect the brain and nervous system.

The Brain: A Brief Review

The brain is the part of the central nervous system located within the cranium. It’s composed of many different parts and regions. For example, the cerebrum is the major portion of the brain that’s involved in complex visual and auditory processes, as well as higher level things like thinking. Then there’s the brainstem, which is the reptilian portion of the brain that looks like a stem. It’s involved in many important processes like the regulation of the heart and lungs. Deep within the cerebral hemisphere, the two halves of the cerebrum, lies the thalamus, which acts like a relay station for bodily functions, and there are many other structures covered in many other lessons. The key thing to note for this lesson is that all of these parts can be affected by drugs one way or another; no part of the brain is immune. You’ll see why in just a second.

Drug Interactions

The way drugs are classified depends on how the classifier wants to well, classify, them. Here’s what I mean; some drugs can be classified based on their use. Like, are they used for medicinal purposes or recreationally? Some can be classified based on their effects on the body, particularly the central nervous system, CNS. Others are classified in further, different ways. We’ll focus on the major drug classifications based on how the drug affects the central nervous system, mainly the brain. These three major classifications include stimulants, depressants, and hallucinogens.

Stimulants are drugs that accelerate the activity of the central nervous system. As illegal as this may sound, you have almost certainly used a stimulant because you probably drank a cup of morning joe at least once in your life, or once every hour of every day of your life. The stimulant you drank: caffeine. Other examples of stimulants include nicotine, cocaine, and amphetamines. Hopefully these guys you never touched. Regardless though, do you know what your morning stimulant does to you? Makes you feel a lot more alert, energetic, and maybe a bit jittery or anxious too, right? That’s because stimulants accelerate the activity within the central nervous system and this is how it manifests itself in your body.

Now, in the case of illicit stimulants, this effect can be so profound that it kills a person because too much stimulation is bad. Like an engine that’s revved too hard for too long can simply go up in flames, the same thing happens with the intake of too many stimulants. Our body’s electrochemical processes simply short circuit from overload and cease functioning. That means we die.

The complete opposite of stimulants are depressants. These are drugs that slow the activity of the central nervous system. Basically, they cause you to ‘chillax’ and become sleepy, even feel less pain. Note how by depressant I don’t necessarily mean your mood changes to a depressive one. The word is used to describe how the drug affects the central nervous system. Examples of depressants include alcohol, benzodiazepines like valium, and tranquilizers. A little alcohol won’t kill you, but an overdose of a tranquilizer will. Why? Lets turn to another metaphor. Think of a clock tick tocking away on battery power; if you were to all of a sudden remove the battery power, the signal to keep tick tocking away, the clock would stop. Depressants force the CNS to work really slowly or not at all. It’s like removing the battery from you body. This removes the signal for the body to keep functioning including the tick tock of the heart. Thus, an overdose of a depressant can cause the heart and lungs to cease functioning, once they lose the signal to keep beating and breathing.

The final major drug class I want to mention is the hallucinogens; drugs that alter a persons sensory perception and thus alter the messages and signals within the CNS. So these are the guys that cause you to see, hear, smell, and even taste things that are simply not real, or sound or look very different in real life. Examples of hallucinogens include LSD, psilocybin (found in certain mushrooms), and mescaline (found in the peyote cactus). These drugs can be thought of as inducing a game of broken telephone within your brain. Instead of a clear signal being carried through to perceive a sense as the way it is, the message gets garbled, as it makes its way from the sensor to the brain, causing the brain to interpret the sensation in a completely different way.

Lesson Summary

The brain is the part of the central nervous system located within the cranium. It can be affected by stimulants, depressants, and hallucinogens. Stimulants are drugs that accelerate the activity of the central nervous system. Examples of stimulants include nicotine, cocaine, and amphetamines. Depressants are drugs that slow down the activity of the central nervous system. Examples of depressants include alcohol, benzodiazepines like valium, and tranquilizers. And finally hallucinogens are drugs that alter a person’s sensory perception and thus alter the messages and signals within the CNS. Examples of hallucinogens include LSD, psilocybin, and mescaline.