In this video I describe the 3 main classifications of psychoactive drugs: stimulants, depressants (including narcotics), and hallucinogens. I provide several examples of each drug type, the associated effects on the nervous system, and the relationship to concepts of neuroadaptation, withdrawal, tolerance, and overdose.

Don’t forget to subscribe to the channel to see future videos! Have questions or topics you’d like to see covered in a future video? Let me know by commenting or sending me an email!

Check out my psychology guide: Master Introductory Psychology, a low-priced alternative to a traditional textbook: http://amzn.to/2eTqm5s

Video Transcript

Hi, I’m Michael Corayer and this is Psych Exam Review. In this video I want to go over the three main classifications of psychoactive drugs and these are stimulants, depressants, and hallucinogens.

So we’ll start by looking at stimulants. So stimulant refers to a drug that stimulates the nervous system. This means that the effects are going to include increasing heart rate and blood pressure and breathing and this can also be associated with a state of vigilance where we’re more sensitive to threats, although in the extreme this can lead to paranoia and decreased feelings of tiredness. Now many stimulants also stimulate a region of the hypothalamus called the nucleus accumbens. This is also known as the reward area of the brain and this is normally activated from behaviors like eating or sex and so what these drugs do is they cause a rush of activity in this nucleus accumbens and this can cause short-lived feelings of euphoria for the user. And this explains why these drugs can be quite addictive.

So examples of stimulant drugs are cocaine, caffeine, amphetamine, methamphetamine, and MDMA or methylene dioxymethamphetamine, also known as ecstasy. And as we’ll see MDMA is also a hallucinogen, so this is a good reminder that drugs can fall into multiple categories. They can contain multiple different types of molecules that influence the body in different ways, in the same way that a vodka redbull could be a stimulant because it contains caffeine and a depressant because it also contains alcohol.

Now it’s possible to overdose on stimulant drugs and this can be deadly. One way that this can happen is that the heart can be accelerated so quickly that blood flow can no longer happen in the body. So if you think about the way that your heart normally works, it contracts and then it relaxes, and blood flows in and then the heart contracts again and this pushes that oxygenated blood out to the body. And if you imagine your heart beating very very rapidly you realize that there’s no longer any time for blood to flow back into the heart and this means that the blood can’t get oxygenated and it can’t carry oxygen to the rest of the body and this can cause a person to faint or become unconscious and it can even cause death. Now this is true of stimulant drugs that we generally might think of as harmless like caffeine.

So caffeine is the most widely used psychoactive drug in the world and yet it has the potential for deadly overdose. You take too much caffeine. Your heart can beat too quickly and this can cause you to die and occasionally you might read about this in the newspaper. You hear about you know a teenager who was dared to drink a dozen Red Bulls or something and that’s important remember that there are potentially fatal effects even of something like caffeine.

Ok, so those are stimulants now we’ll move to the next category of drugs and these are depressants. So depressants refer to drugs that inhibit function, alright? They decrease functioning in the nervous system. So examples of depressant drugs would be alcohol, barbiturates, and benzodiazepines which would include drugs like valium and xanax, right? Now there’s a bit of confusion here. Occasionally you probably hear somebody say something like “oh you know alcohol is not a depressant” or “I don’t know why people say alcohol is a depressant because when I drink I get really happy and I sing and I jump on tables and dance and things”. Well, yes, that may all be true but it’s important remember the term depressant refers to the effects on the nervous system, not on mood. It has nothing to do with the mood. So the reason we say alcohol is a depressant because it inhibits functioning and in the case of “well why would that explain somebody jumping around and dancing on tables?” well, it’s inhibiting the parts of the brain that normally would control that behavior.

So normally you think about you know dancing on the table and you think “well that might be embarrassing and people might look at me funny and all sorts of negative things might happen. I could fall and get hurt”. And if you inhibit the function of those regions, that, that’s sort of monitoring for appropriateness, well then now you think about dancing on top of the table and it seems like a perfectly good idea. So remember that this term depressant refers to inhibiting function of the nervous system. Now again, in the case of overdose, we can inhibit functions so much that a person falls into a coma or even dies.

Now I’d like to talk about depressants when it comes to the idea of tolerance and withdrawal because alcohol’s one where people generally understand the idea of tolerance. Somebody who drinks a lot can generally drink more without having the same effect. So what’s going on here and how does this relate to the withdrawal process of quitting alcohol or quitting barbiturates or benzodiazepines? So I talked in the previous video about this idea of neuroadaptation. The idea that the body responds to drugs, it tries to counter act the effects of those drugs.

So in the case of alcohol what we’re doing is we’re decreasing the functioning, that we’re reducing the stimulation of the nervous system and the body responds to this by increasing it, right? It’s trying to balance it back out, it’s trying to get it to a normal level of function. And so what can happen in the case of withdrawal is; imagine that you have some set level you want it to be at in terms of the you know functioning of your nervous system. And if you keep drinking every day, excessive amounts of alcohol every day, you’re going to lower that level of function, right? Because you’re inhibiting and so your body’s going to do this, going to push back against this. The neuroadaptation is going to try to push that level.

So actually you’re starting way up here very high stimulation and then you’re drinking every day and you’re at sort of a normal level of functioning. That’s what’s going to happen over time. Well, now you can see what happens is when the person quits alcohol. Suddenly their level of stimulation, they sort of realize their body has set it way up here and it’s been relying on alcohol to bring that back down to a normal level. So this explains the withdrawal effects that happen when somebody tries to quit alcohol if they’ve been drinking excessively for a long period of time. Then what are the effects that they experience when they quit?

Well they experience anxiety. They feel, they feel too much stimulation. This is called excitotoxicity and you’ve probably seen this in what’s known as the DTs; Delirium Tremens, right? You might be familiar with this term and this refers to the shakes that somebody who is addicted to alcohol experiences when they haven’t had enough to drink. They haven’t inhibited their functioning enough, so they’re overexcited. They go, this can work in severe alcoholics this can happen, within you know a few hours of not drinking. They start shaking and this can also happen to their heart. They can have heart palpitations and extreme anxiety and this can actually be deadly. So if somebody’s severely addicted to you alcohol or benzodiazepines and they try to quit completely without any medical supervision, it can actually cause severe enough excitotoxicity that they die.

So this is why it’s important in these extreme cases that people have medical supervision and it’s important to recognize that, you know, their body really is craving the alcohol and they really do need to be monitored in order to gradually reduce this over-stimulation that occurs from the tolerance that has been built up to the alcohol or to whatever the depressant drug they’re addicted to is.

Ok, so now I want to talk about narcotics. Now narcotics are a type of depressant but there’s a little bit of confusion here and that’s because the term narcotic has a legal definition that’s different from the medical definition. So in terms of US law any drug that’s illegal can be referred to as a narcotic. So you can refer to cocaine as a narcotic even though it’s a stimulant, and you can refer to marijuana as a narcotic even though if it’s a hallucinogen. So what I’m going to do is explain the medical definition. So in medical terms narcotic comes from the Greek narkos which means numbness or stupor. And so this refers to type of drugs which are depressants but these are a class of depressants that mimic the body’s natural painkillers. They mimic endorphins and so this means that they reduce pain and they induce a sort of drowsy bliss in the user.

So narcotic drugs would include morphine, heroin, methadone, oxycodone, codeine, and opium; which is where we get the term opiates and opioids. And in the case of narcotics we can see that this withdrawal process is quite horrible for the user because what happens is they’re using these drugs that mimic endorphins and so this actually reduces their body’s ability to produce its own endorphins. It reduces the body’s ability to manage pain and so when they stop using the drug they actually experience terrible amounts of pain and their body isn’t able to reduce this pain on its own, right? And this very often drives the person back to the drug.

We can see this is why addiction to these drugs is so terrible. People will do just about anything to get these drugs because they’re essentially being tortured, right? They’re in a great deal of physical pain and the only thing they can do to try to cope with this is often use the very drug that they’re trying not to use. So this explains why these drugs can be so powerful and they can exert such a terrible amount of control over people’s lives. Ok, so those are narcotics.

Now we’ll move to the last class of drugs and these are hallucinogens. So hallucinogens are drugs that are able to alter our perception. So they can alter our perception including our sense of identity and they can induce hallucinations. So they can cause us to see or hear or feel or even taste or smell things that aren’t actually there. So examples of hallucinogens would be LSD, mescaline, psilocybin mushrooms, marijuana, PCP, ketamine and as I mentioned before, MDMA. Now the effects of hallucinogens are little bit less predictable and this is because they seem to have a strong relationship with people’s expectations and their emotional state. So they don’t have the same types of predictable effects on the nervous system that we see with stimulants or depressants. I mean partly because they’re altering perception and so they’re gonna be more influenced by the expectations the person has, the situation that they’re in.

Now another interesting effect of hallucinogens is that they can have what’s called reverse tolerance and this is because they remain in the body longer. So for instance the byproducts of THC in marijuana can linger in the body for up to a month after use and so this reverse tolerance refers to the idea that sometimes people can experience a greater high from the drug in subsequent uses with a smaller amount. So normally we have tolerance and people need to increase the amount of drug that they use over time, right? So if you are addicted to alcohol you have to drink more and more to get the same effects. The same would be true of nicotine but in the case of hallucinogens sometimes people use a smaller amount later and they actually experience a stronger effect. It’s because some of the drug is still lingering in their body from the previous use and this might explain why sometimes people report using marijuana and saying that they didn’t get high the first time they used it but they got high the second or third time. This might relate to this idea of reverse tolerance and the fact that some parts of the drug can linger in the body.

Now when it comes to addiction to hallucinogens they don’t seem to have the same physiological addiction and withdrawal or dependence that other drugs have. And one way that we can see this is in animal studies. So if you give a mouse cocaine or methamphetamine, you know, the mouse will work to get more of the drug. I work I mean it will press a lever repeatedly in order to get more of the drug. The same will be true if you got a mouse addicted to heroin or opium and this shows that the drug is physiologically addictive. But in case of hallucinogens, if you give a mouse LSD or psilocybin generally it won’t work to get more of the drug and this suggests that the drugs aren’t physiologically addictive but this doesn’t mean that they aren’t addictive at all because we still have psychological addiction.

So the idea of psychological addiction is if you’re using these drugs in order to escape negative emotions or to cope with stress then you’re going to turn to these drugs in the future. You’re going to have a craving for them in order to deal with negative emotions or in order to deal with stress and so they can still be addictive in a psychological sense. And it’s also important remember that just because they don’t have the same physiological addiction or they don’t have the same capacity for physiological addiction, this doesn’t mean that it’s okay to use them because they do have other problems associated with their use. So hallucinogens are associated with anxiety and paranoia and they can also cause learning and memory problems. So just because they aren’t physiologically addictive doesn’t mean that it’s okay to use them.

Ok, so those are the three main classes of psychoactive drugs. We have stimulants, depressants including narcotics, and hallucinogens. I hope you found this helpful, if so, please like the video and subscribe to the channel for more. Thanks for watching!