This program is brought to you by Emory University. [BLANK_AUDIO] >> This week, we'll begin to discuss the ten classes of abused and addicting drugs. It can be helpful to group these various drugs into classes. If we discover something about one drug in a class, it's reasonable to assume that it will apply to other drugs in the class. Similarly, if a successful treatment is discovered for a given drug, then it may very well apply to other members of that class, so classifying drugs is convenient and has its uses. The ten different classes of drugs are alcohol, tobacco and nicotine and it's really nicotine because nicotine is the substance in tobacco that is addicting. Caffeine, cannabis or marijuana, inhalants, opioids, sedatives and anti-anxiety agents such as Xanax. Psychostimulants such as cocaine and methamphetamine, hallucinogenic agents such as PCP and LSD. And the last class that is sort of a catch all that we call other. It won't be possible to talk about every detail of the drugs in these classes, but I'll select some examples and give an overview. As we go on, we'll cover more and more material about these drugs. We can begin with the first class, which is alcohol, a single drug. Alcohol or ethanol is the addicting substance in drinks. While it is legal, its use is restricted, sometimes by law. For example, while driving. Alcohol is one of the most used and abused drugs on the planet, and it is a significant public health problem. Here's the bad news. In the United States, alcohol ranks third in disease impact, so it is significant. Also in the United States, there are eight million dependent drinkers. Dependent means that if they stop drinking, they will go into withdrawal and feel very, very bad. A third of all cases of all cases of liver disease are associated with alcohol abuse. Alcohol is the leading cause of traumatic injuries in the western world. Finally, there's a strong association between alcohol use and other public health and mental health disorders. There's no argument against the idea that alcohol is a public health problem. Because alcohol is a major concern, the amount that you can drink safely has been explored and considered. A weekly intake of no more than five drinks for men and two drinks for women is associated with lowest mortality. This suggests that a low level use of alcohol may be, in fact, healthy. The NIAAA, which stands for the National Institute for Alcohol Abuse and Alcoholism, recommends no more than 14 drinks per week for men and 7 for women. We see that the recommendations for women are for fewer drinks than for men. Women seem to be more sensitive to alcohol than men. The daily use of over 15 drinks per day for men and 10 for women will likely lead to dependence, so we have a rough idea of the limits of alcohol intake. What are the effects of ethanol intake? Like all drugs, the effects observed depend on the dose that's been given. Roughly, and in accordance with increasing doses, the following are observed. A loss of muscular coordination, changes in mood, personality, and behavior, mental impairment, obvious intoxication, coma, and sometimes death. As I've said about drug use in general, many people can walk away from drinking, but many don't, and dependence and addiction develop. This slide suggests that if you drink fairly heavily for a year, then you will have a 14% chance of becoming dependent. If you drink for five years, there's a 50% chance you'll become dependent. So, it is not a small problem and the odds that you can get into trouble are significant. As I mentioned earlier, dependence implies that if you stop taking alcohol, you will go into withdrawal. And alcohol withdrawal can be very serious. The signs that appear depend on the stage and degree of addiction. For example, you might observe tremor, insomnia, nausea or vomiting, hallucinations, anxiety and agitation, and even seizures. Sometimes, death occurs during withdrawal in those individuals who are severely addicted. How does alcohol work? It looks as though are, there are a couple of important mechanisms by which alcohol produces its rewarding effects. First of all, it has been observed that ingestion of alcohol causes a release of dopamine in reward-related areas of the brain. It's known that the opioid systems are involved. The opioids are the naturally occurring neurotransmitters related to opiate drugs. Opioid blockers reduce drinking, which is an important treatment option. Also, alcohol increases the action of GABA, which is an inhibitory neural transmitter, and it blocks a Glutamate receptor, the NMDA receptor, and Glutamate is an excitatory neural transmitter. So, alcohol increases inhibition and decreases excitation, suggesting an overall depression of neuronal activity. This is likely related to the impairment that we commonly witness in people who have taken alcohol. There are other suspected mechanisms of action as well that we won't discuss here. In previous lectures, I've talked about ethanol metabolism. Ethanol is broken down in the body by various enzymes that eventually produce acetate. Acetate is inactive and so, ethanol is metabolized to an inactive substance. Three standard drinks of any kind in rapid succession can challenge the capacity of metabolism and result in impairment of driving and significant blood alcohol levels. It could take four to five hours to completely metabolize that amount of alcohol. Spreading out the intake over time would give metabolism more of a chance to keep blood levels lower. Let me summarize what I've talked about. First of all, it's clear that alcohol is a dangerous substance, particularly when consumed in large quantities. Its effect, its effects are synergistic or additive with those of other sedatives and therefore, other sedatives such as Xanax or Valium become more dangerous. There's evidence that alcohol produces cell death in the brain, and, of course, we know that alcohol produces addiction tolerance and withdrawal. I will talk about treatment in more detail later in the course, but at this point in time, let us simply say that there are effective treatments available. There are medications and support groups, and we know that treatment works. You should be familiar with the website of the National Institute on Alcohol Abuse and Alcoholism. It's an excellent source of information of all kinds. If you have an interest in this area, you may want to go to that site.
