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Video transcript

- [Instructor] Let's consider drugs. I'm also going to call them substances. And as you know, there's a whole bunch of different drugs and substances that people use. Some of the most common ones include alcohol and tobacco, but also there's a range of other ones including cannabis, opioids, that includes things like heroin, also things like stimulants, and that includes things like cocaine and amphetamines, and a whole bunch of other things including hallucinogens, and that includes things like LSD, inhalants, hypnotics, sedatives and other things. And let us not also forget one of the most commonly used substances which is caffeine commonly found in your mug of coffee or tea. So when we look at drugs, when we consider drugs, there's several things that we have to also kind of look at. So, we have to consider what happens when drugs enter the body, and also what happens when they exit. These are two different processes. The first process, when the drug actually goes into a human body, we can actually call this intoxication. And that's when the drug exerts its effect on somebody when it goes into their body. If it exits after a period of prolonged use, we may experience something called withdrawal. So what are we talking about when we mention intoxication? We're talking about both the behavioral and psychological effects of the drug on the person, and these can be very much drug specific. So, can we think of some examples of intoxication? Well let me give you a couple of examples. When we're drunk, that's an example of intoxication with alcohol. Or when we describe somebody as being high, that again, is a lay, colloquial way of describing where someone is intoxicated with another substance, which may be something like cocaine or heroin, for example. So, what about when a substance actually exits a person. Well, withdrawal happens when we stop a substance, stop taking a substance after having taken it for a prolonged period of time. And what happens there, is that we get withdrawal symptoms, symptoms of stopping the drug. And these symptoms can make us feel quite sick or ill, and in some cases, can be quite dangerous or potentially fatal, depending on the drug. And when I say drug, I should also say substance here. That's a more formal way of referring to it. Both intoxication and withdrawal, the effects really vary on the precise drug or substance that we are using. But let us also think about drugs or substances in a different way. Let us think about them on their effects on the human brain. Well know these substances can actually result in a whole heap of other conditions, because they can result in something called substance induced disorders. These are conditions that are actually caused by substances, and these are conditions that could be substance induced mood disorders, disorders of mood, either experiencing moods that are too high, like mania, or moods that are too low, like depression, disorders related to anxiety, sleep, sexual function. We may also get problems with something called psychosis which is a loss of contact with reality, and that's where people can hear voices or see things, or become very paranoid. Now, when these drugs affect the brain, something completely different may also happen. We can actually have the development of a substance use disorder. Not everybody that uses a substance develops a substance use disorder, which basically implies that when they use this drug, the way that they're using the substance or the drug is causing them a real degree of impairment. It's really affecting the way they function in their life. Whether that's at school, work, or at home, their drug use is really impairing. Now let us talk about substance use disorder a little further, because when we talk about substance use disorder, the main issue that we are looking at is that there is a problem here. There is a problem with their substance use. And again, not everybody that drinks alcohol or smokes cigarettes or uses a substance, not everybody has a substance use disorder, but some people do. So let's have a closer look at this. How do we know they have a substance use disorder? One of the ways that we can find out is by looking at their use. And there's really important factors that we need to consider here. Are they using increasingly large amounts? Are they experiencing increasing craving or strong desires to use? Are they spending more and more of their time recovering from, or trying to get the substances? Are they failing to try and cut back or cut down? And also feeding into this use issue, are they experiencing problems related to their obligations at work, at school, at home? If these things are appearing, that really does suggest that maybe there is a problem and maybe they have a substance use disorder. A second factor that we look at, apart from use is the presence of something we talked about earlier, and that was the presence of withdrawal. Now this is something that happens after you stop using the drug after prolonged or sustained use, and you can feel pretty sick or unwell with different symptoms depending on whatever drug you're using after having stopped the drug. And this really also suggests that physiologically you're dependent on the drug, your body's dependent on the drug. Withdrawal can be dangerous. For example, alcohol withdrawal. You can get seizures potentially, and die. Withdrawal symptoms are specific to the substance. So again, the presence of withdrawal suggests that you have a problem. Finally, the last thing I want to mention, is the presence of something called tolerance. What tolerance is, let me graph it out for you. If this is the effect, and this is the dose, the effect of the drug decreases with subsequent doses. Your body adapts to, or builds a tolerance to the substance. So what people do, in order to overcome this tolerance, is they tend to keep increasing the dose or the amount of the substance they use in order to achieve the same level of intoxication. So, as we can see, the way that people are using, and the problems that they are encountering with the substance, the development of withdrawal symptoms and the development of tolerance all suggest that we have a problem. Actually, just having a couple of these, such as craving or withdrawal or having using increasing amounts, not being able to cut down, is enough for us to be able to diagnose a substance use disorder. And there's different severities of substance use disorder, from mild, moderate, to severe. The one caveat I would say, is that caffeine, of all the drugs that I've mentioned, with caffeine, we cannot develop a substance use disorder, according to the common criteria. Now that may be an arbitrary thing, but I just want you to know that.