Skip to 0 minutes and 10 secondsHave you ever noticed how coffee, or alcohol if you drink alcohol, seems to affect you less over time? Perhaps you've heard someone being referred to as a hardened drinker. And perhaps you know somebody who can consume far more drinks than you can and not seem to be affected. Or perhaps you know of someone who's been taking, for example, pain medication for a chronic condition and has started to say that on a particularly bad day, these tablets just don't work anymore. Each of these examples is an instance of tolerance. Simply put, tolerance to a drug means that over time and with repeated use, larger and larger doses are required to achieve the initial experience. These effects wear off with repeated use.

Skip to 1 minute and 4 secondsSo you need to drink more coffee to feel like you did when you first started drinking it to feel that buzz. You find you need to more alcohol, and you can drink more alcohol without becoming drunk or feeling intoxicated. Or you may find that you need stronger and stronger doses of painkillers to relieve your discomfort. Tolerance shows how the brain strives to be in balance. It constantly adapts and changes so to function in a way that we can act and feel normal, a process called homeostasis. And when we talk about homeostasis occurring in the brain, we use the term neuroadaptation.

Skip to 1 minute and 45 secondsOver time and with frequent drug use, our brain adapts, so much so that it's only in balance, that is it's only functioning normally, whilst the drug is present in the brain. When the drug starts to wear off or when we try to stop using it, our brain's no longer in balance, and we experience an uncomfortable syndrome of signs and symptoms. And these signs and symptoms we call withdrawal. We experience them as the opposite of the effects of the drug. Those of us who ever had a sugar rush, you know when you've taken too many lollies. And you know that for a little while, you're giddy with excitement. You're buzzing.

Skip to 2 minutes and 26 secondsBut then as it wears off, you start feeling groggy, lethargic, and maybe even a little bit depressed, quite the opposite of the effect of sugar in the first place. Now, if we take a drug that makes us feel euphoric or high, then the withdrawal syndrome will be experienced as dysphoria or sadness. It's always the opposite. In the context of addiction, if you take the drug, you'll stop those symptoms immediately. So if you're starting to feel sad, you just take the drug, and bam. They're gone. And this can motivate continued use.

Skip to 3 minutes and 8 secondsYou might remember from the start of this lecture how I described how drugs increase the activity of a neurotransmitter called dopamine in the reward centre of our brain and that this gives us great pleasure. Well, over time, the brain will adapt to these overwhelming surges of dopamine. It does so by producing less dopamine or by reducing the functioning of the dopamine reward pathway. The impact of this is that the person's ability to enjoy not only drugs but also other aspects of their lives is significantly reduced. And so withdrawal symptoms might be experienced as quite intense soon after giving up drugs.

Skip to 3 minutes and 54 secondsBut in the longer term, it can also leave us with a long-lasting feeling of sadness or dysphoria, of craving, which might last for months after we've stopped using a drug. And this is occurring because our brain is re-adapting to the absence of the drug. It's trying to get back into balance. Tolerance and withdrawal put together represent the biological components of addiction. Some may call this physical dependence or physical addiction. And it results from our body trying to counteract the presence of a drug. The amount of alcohol or other drug used increases as a response to tolerance.

Skip to 4 minutes and 39 secondsAnd over a period of time, the level of drugs that you're using, the level of alcohol that people are drinking, might reach levels that many would find astonishing. People using opiates such as heroin after a period of time can take doses and function normally at levels that might kill novice users or first-time users.

Skip to 5 minutes and 2 secondsAddiction develops slowly.

Skip to 5 minutes and 7 secondsLet's go back for a second to the DSM criteria. As I was presenting those criteria, we can note two broad defining features. Firstly, an increasing preoccupation with obtaining, and using, and recovering from the effects of a drug, so much so that other interests-- jobs, relationships and so forth-- are ignored. And secondly, continuing to engage in this behaviour, to use these drugs despite being aware of obvious physical, or psychological, or social harms, and continuing to use despite attempts to stop. Neglect of important areas of one's life to focus upon addiction inevitably leads to problems. Our relationships may break down. We may lose our jobs. Our health might suffer. These problems are often the most debilitating aspects of an addiction.

Skip to 6 minutes and 4 secondsAnd ironically, the stress that they cause can actually lead people to turn to further engagement in addiction. The problems caused by addiction can in turn become motivators strengthening addiction. A vicious cycle starts to develop. Addiction is characterised perhaps most dramatically by those people who continue to use drugs despite experiencing significant harms. This concept of addiction as a compulsion, the inability to resist that impulsive need, that craving, this concept for me marks our understanding of addiction. And it marks where neuroscience, and pharmacology, and psychology, and medicine, and addiction science are making the most advances.

Skip to 6 minutes and 59 secondsFinally, let's ask ourselves some questions. Is addiction a disease? Is addictive behaviour a choice? Can you just say no? People sometimes assume that people with addiction lack moral strength or willpower. Why else would they continue with something that's obviously causing them so many harms? Surely to stop an addiction, all one needs to do is decide not to use anymore, to decide to stop. Well, in future lectures in this course, we're going to look at the risk factors for developing an addiction. And we're going to explore why some people become addicted and others don't.

Skip to 7 minutes and 39 secondsWe will discuss how genetic susceptibility might account for maybe half of the risk for developing an addiction, and other risk factors as well in the social and psychological environment, factors such as the role of family and friends, parenting skills, peer pressure, and socioeconomic status. We'll discuss how these risk factors can increase the chances of developing addiction. We'll explore how our genes and the environment in which we live interact with critical stages of our development to affect addiction vulnerability. So what are the take-home messages from this talk? Addiction is a chronic, often relapsing disorder. It's driven by changes in brain function.

Skip to 8 minutes and 29 secondsAnd there are associated impacts on our psychological and physical health, and of course on the environment, the people around us. Addiction causes people to act compulsively. They find it difficult to resist an impulse. And addiction causes people to spend more and more time seeking out the drug or the object of affection, the object of addiction, using the drug, and then recovering from the effects. And people continue to do this, seek the drug, use the drug, and recover from its effects, despite obvious harms to themselves and the people around them. Although the initial decision to take drugs is voluntary for most people, the brain changes that occur over time affect self-control.

Skip to 9 minutes and 22 secondsThey affect the ability to see the future consequences of behaviour and the ability to resist impulses.

Skip to 9 minutes and 31 secondsAlthough there is no panacea, no quick fix, successful and effective treatments are available. And research shows that combining medications with psychological therapy or counselling helps the majority of people. Treatments that are individually tailored, to the individual circumstances and needs, do even better. But we need to remember that the journey out of addiction can be a very long one. And it's common for someone to relapse and start using the drug again. Relapse doesn't need to be seen as a failure, but rather the need to learn about what went wrong and then try again, perhaps try a different form of treatment. The diagnostic criteria for addiction, and indeed the primary models and theories of addiction, are revised and changed over time.

Skip to 10 minutes and 25 secondsWe currently lack a single, unified theory of addiction. But current research is taking us ever closer to such a theory. And within the last few years, some of the key neuroscientific and pharmacological components of addiction have been identified. And we'll explore some of these over the course of the next six weeks. So when we ask ourselves the questions, is addiction a disease? Is it a choice? Can we just say no? Well, well what I hope you've realised is that the answer isn't simply going to be yes or no.

Skip to 11 minutes and 1 secondUnderstanding what addiction is, why some people develop addiction and some don't, why some people can use a drug and not become addicted, but for others that road to addiction happens quite quickly, and for those who do become addicted, how can we best treat or prevent it? Well, these are complex, fascinating, and I think very juicy areas of science. The lectures in this course will show what we currently know about addiction. We will describe where addiction science is and where it's going to take us next.

Skip to 11 minutes and 39 secondsI really hope you enjoy your journey learning about addiction. And thank you for your time. And I wish you well, and I'll see you next time.

What is addiction? Part 2

In this second short video, I continue our exploration of the fundamental diagnostic criteria for addiction, including introducing us briefly to the principles of tolerance and withdrawal.

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Understanding Drugs and Addiction

King's College London

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