Addictive Drugs

Operant Conditioning

Operant conditioning teaches drug users that taking a drug produces pleasure. As a result, drug users take more of the drug. Because drugs of abuse directly activate the brain reward system, the positively rewarding qualities of the drug powerfully reinforce drug-taking behavior. Operant conditioning also teaches drug users that a drug can relieve unpleasant feelings, such as anxiety and stress. So, people learn to take the drug to relieve these negative feelings. The result is that negative...

The Limbic System

Main Components The Limbic System

To complete the overview of how your brain works, you need to consider one more set of structures in your brain called the limbic system (Fig. 3.5). Your limbic system creates your feelings and motivations. Your feelings supply the contexts for your sensory and motor activities and can alter how you perceive the world and behave in it. The limbic system, which evolved after the brain stem but before the cortex, sits between them. Its location provides an important clue to part of its function...

Exciting the Neuron

Neuron Image For Team Work

When an excitatory neurotransmitter binds to a receptor, it encourages the neuron to fire off an action potential. Although excitatory neurotransmitters tell neurons to fire action potentials, a single excitatory neurotransmitter cannot do the job by itself. A number of excitatory neurotransmitters must bind to a number of the neuron's receptors before the excitatory message is strong enough to actually elicit an action potential. The teamwork required to do this is another way the neuron makes...

Drugs Are False Messengers

In some parts of the brain, drugs actually send false messages. In other parts, they weaken or intensify real ones. But no matter how they disrupt communications in other parts of the brain, nearly all drugs of abuse mimic the actions of the neurochemicals that make people feel pleasure when their brain reward systems are activated. Drug users describe the intensified pleasure produced by drugs as being high. In fact, drugs turn on the reward system with a...

Current Drug Usersfuture Addicts

To explain how drugs change the brain and produce addiction, we will follow the histories of several people whose involvement with drugs ranges from initial use to full-fledged addiction. Some are addicted when we meet them. Others may not become addicted. Most will. Let's meet them now. (Unlike the people whose letters appear in the preface, the drug users we are about to introduce are not real people, but composites we have created. They are based on the interactions we have had with...

Dose and Route of Administration Interaction

Most people understand that as drug users increase the dose of a drug, it will have more powerful effects. That is, the effect is dependent on the dose. For a psychoactive drug to have an effect that users can feel and discern, a specific amount (an effective dose) must reach the brain. If the user takes too little, she can't perceive that anything is happening. If the user takes too much, he may develop symptoms of an overdose, such as getting sick or passing out. What many people do not...

Why The Route Of Administration Matters

Because so much of the heart's output of blood goes to the brain, any route of administration that deposits a large amount of drug into the blood quickly will promptly get a large portion of that drug to the brain. In contrast, a route that gets the drug into the blood more slowly decreases the rate at which it gets to the brain and, because of the way the body eliminates drugs, will probably also reduce the amount of drug that finally does reach the brain. Why this is so will be described in...

Explicit Learning And Memory

Learning occurs in two fundamental forms conscious and unconscious. With conscious learning, which psychologists also call explicit learning, we use our senses to find out what is in the world and where and when events have occurred. We take in information about what we see, hear, smell, taste, and touch, and our brain stores that information in its short-term, or working, memory. Our brain's working memory allows us to retain information long enough to perceive it, use it, perhaps mull it over...

Drugs Teach Animals to Take More Drugs

Laboratory experiments with monkeys illustrate just how powerfully drugs turn on the reward system. Scientists insert a special catheter into a monkey's vein. The catheter is hooked to a pump that pushes a specific dose of cocaine into the blood each time the monkey presses a bar to which the pump is attached. This monkey has been trained to press bars that release food and water, but now the scientist has introduced a third bar, and pressing this one releases cocaine into the monkey's...

Psychological Dependence Physical Dependence Addiction

It is the eventual addition of psychological dependence to physical dependence that heralds the onset of addiction. Physical dependence is one of the necessary components of drug addiction, and almost everyone who becomes physically dependent on a drug because of drug abuse is at great risk for becoming addicted. But being physically dependent on a drug is not the same as being addicted. Let's reiterate this point because it is often misunderstood Physical dependence is a necessary component of...

Physical And Psychological Dependence Revisited

We have taken this digression to explain about the biological basis of psychological dependence and the need to use psychological concepts to define states that are really neurobiological. We have done this to clarify the reasons why our language sometimes confuses our understanding of abuse and addiction. Remember that both types of dependence, physical and psychological, are biological because drug-induced changes in brain function lead to both. Still, each type of dependence is different...

Is Marijuana Medicine

Although we have reached a reasonable accommodation in balancing the risks and benefits of medically used opiates, we are far from such a reconciliation as we grope for a way to evaluate any potential medical use of marijuana. If our drug laws and policies can make room for the appropriate medical use of the highly addictive opiates, can they also make room for the appropriate medical use of the cannabinoids, which do not have the same addictive potential as opiates Can we make a risk benefit...

Addictive Drugs Disrupt Neurotransmission

Addictive drugs change the brain's communication system by interfering with synaptic transmission. Some drugs mimic certain neurotransmitters and convey false messages. Other drugs block neurotransmitters and prevent real messages from getting through. Still other drugs have different kinds of effects that modify the flow of information among neurons. But all addictive drugs interfere with the way neurons communicate. They change the way the brain works, and that changes how people perceive the...

The Reality of Relapse

Another reason why people believe treatment doesn't work is based on misperceptions about how the process of recovery usually works and what the phenomena of craving and relapse mean within the recovery process. If you've ever tried to quit smoking cigarettes or you know someone who has, you almost certainly are familiar with relapse and the difficult path that recovery can take. In fact, because of what we learned about recovery from addiction, we can now add one more facet to our definition...

The Drug Abuse Control Laws

The drug abuse control laws had a dual task to reduce drug abuse and, at the same time, to preserve our ability to use even abused drugs in medicine when they are needed. Like the food and drug laws, Congress passed and amended the drug control laws throughout the 20th century. And, just as Congress established the FDA to oversee the food and drug laws, Congress established the Drug Enforcement Administration (DBA) to oversee the drug control laws. To control drugs and at the same time make...

Whats The Difference Between Cocaine And Crack

When cocaine started to make its big comeback in this country in the 1970s, snorting was the major route of administration. At that time, people could not smoke cocaine (it was only available in powder form), because it burned rather than vaporized. Some users injected the drug, but most were not willing to do this. People could smoke cocaine by chemically converting it to its free-base form, but this was a dangerous process that required highly flammable chemicals and a flame to heat them...

The Brain Reward Systemthe Real Drug Scene

We will not try to describe every effect of every drug. Instead, we will use a small number of well-known or obvious effects to highlight some of the key points about each drug. In every case, we will focus on how the drug turns on the brain reward system. We discussed the brain reward system briefly in Chapters 3 and 4. Now, let's enhance that description. A group of dopamine-releasing neurons, called the ventral tegmental area (VTA), forms the core of the brain reward system (see Chapter 3,...

Designer Drugs

In the same way that legitimate chemists try to make useful drugs to meet the needs of patients, illicit chemists have tried to make drugs to meet the needs of drug dealers, abusers, and addicts. Until relatively recently, the Controlled Substances Act, the law designed to control the availability of drugs that people abuse, listed each illegal drug according to its specific chemical components. Basement chemists could accommodate dealers by slightly changing the chemical structure of a drug to...

Direct Effects Of The Drug

At least two sets of mechanisms lead to and maintain addiction. First, there are the direct effects of the drug itself. When the brain is repeatedly exposed to drugs, tolerance and physical dependence inevitably develop. Based on the difference between heroin addicts and pain patients who are taking strong opiates as medication, it is now reasonable to believe that additional changes take place in the brain that account for the psychological dependence that distinguishes addiction from...

Abnormal Changes In The Brain

Not all changes in the brain are normal or healthy. In some brain disorders, such as Parkinson's disease and Alzheimer's disease, neurons actually die. External injuries to the brain, such as blows to the head, can also kill neurons. So can internal injuries. Strokes, which occur when a blood vessel in the brain gets blocked, prevent blood from reaching part of the brain. Without blood, neurons become starved for oxygen and, like any other cell starved for oxygen, they die. Unfortunately, the...

The Rate Of Drug Delivery Is Important

In addition to the route of administration, the rate at which the drug reaches the brain is also important. For example, injecting heroin is popular among opiate addicts because it delivers heroin into the brain so swiftly. In fact, heroin is really nothing more than two morphine molecules linked together by a simple chemical reaction. Once heroin gets into the brain, the body breaks it down again into morphine, which then binds with the opiate receptor. Why then do addicts use heroin instead...

Acknowledgments

A number of people have made the publication of this book possible. We express our appreciation to our editor Sally Cheney, for her guidance and patience throughout the creation and completion of the manuscript, and to our copyeditor Alison Kelley, for her insights and many helpful questions that enabled us to clarify key points. We also thank Dr. Elaine Johnson, former director, and Kent Augustson, former associate director, of the U.S. Center on Substance Abuse Prevention, which funded a...

Physical Dependence Manifested Psychologically The Story Of Cocaine

We can see the implications of the failure to understand the true nature of craving with the cocaine epidemic of the 1980s. One reason why this cocaine epidemic became so severe was that we did not understand then that the psychological symptoms of withdrawal are as much a result of biological changes as any of the other physical withdrawal symptoms, such as diarrhea. At the beginning of the 1970s, most people believed that to be addictive, a drug had to produce physical dependence, as measured...

The Timing Of Drug Delivery Is Important

A third factor also influences the high that drug abusers seek. Many drugs produce euphoria only when blood levels of the drug are rising for the first time during a bout of drug use. This is readily apparent with alcohol. As drinking starts and blood alcohol levels climb past a certain point, the drinker typically feels euphoric and has increased energy he or she is high. But even if the amount of alcohol in the blood continues to climb, which it will do as long as the rate of drinking exceeds...

The Brain Reward System

A key to understanding how drugs work lies in a group of interconnected brain parts, which reward you when you do the things you need to do to survive. This brain circuit produces reward by making you feel pleasure when you do these things. You eat and drink so that you can survive. Eating and drinking make you feel good. You have sex so that your species can survive. Sex, too, makes you feel good. The feelings of pleasure that result when you accomplish survival-oriented tasks are caused by...

Localization Of Function

Your brain can cope with complex tasks because of the way it is organized. The rules that govern its organization evolved along with the brain itself. One of these rules is particularly useful to consider, because it makes it easier to understand how drugs act on the brain. This rule, called localization of function, says that specific places in your brain carry out specific functions of your brain. For example, your brain directs the information coming from your eyes to a region toward the...

Typical Tasks Your Brain Performs When You Drive

Before we actually consider how your brain is organized to carry out its tasks, let's look at some of the things it must do during a task such as driving. For example, you are driving to the supermarket to buy food for a special dinner you are going to prepare for important guests. First of all, you can't drive if you are asleep. Therefore, your brain must control all the different parts of your body that keep you awake and alive. At the same time, your brain must prevent your bodily needs from...

Basal Ganglia and Nucleus Accumbens

Many regions of your brain stem and other brain structures that lie below your cerebral cortex work together with the cortex on certain kinds of Figure 3.3 The basal ganglia and thalamus as seen with the near hemisphere of the cerebral cortex removed. Figure 3.3 The basal ganglia and thalamus as seen with the near hemisphere of the cerebral cortex removed. jobs. Some of these structures receive information from sensory organs, such as your eyes and ears, and relay this information to your...

The Development Of Modern Medicine

Even at the beginning of the 20th century, average life spans were almost three decades shorter than life spans of today. Infant mortality rates were heartbreakingly higher. Only a few generations ago, parents routinely named several sons after their father in the hope that at least one son would survive to adulthood to pass the father's name on to the next generation. Improvements in public health and nutrition have made big differences, but it was the development of vaccines and the...

From Active Drug to Inactive Metabolite

We commonly use the term metabolism to describe how the body's enzymes extract energy and other nutrients from food by breaking it down into components our cells can use. But metabolism has a broader meaning as well, and it includes all the processes by which the body breaks things down. Thus, the stomach and intestines contain metabolic enzymes that digest (break down) food, whereas cells contain other kinds of metabolic enzymes that extract the energy from sugar and fat. The liver and many...

Treatment Is A Transition

The long-term abuse of drugs causes profound changes in the brain. The behavior of addicts is strongly influenced by the maladaptive learning that takes place as addiction develops. As a result, recovering from drug addiction does not mean returning to a condition like the one that existed before drug abuse began. Instead, addicts must grow into a new level of personal awareness, with new patterns of behavior. That is one reason why the treatment of addiction is so difficult. Still, treatment...

History Of Opiate

Opiates are among the most addictive drugs known to man yet their medical usefulness has nonetheless spanned the millennia from ancient remedy to modern pharmaceutical. In the early 1800s, significant advances in chemistry and technology allowed pharmacology and medicine to leave the Dark Ages, so to speak, and begin the development of the modern drugs and medical procedures we make use of today. Advances in chemistry led the way, allowing scientists to break down the crude drugs found in...

Henrys Nearlethal Alliance With Heroin

As we see with Henry, who overdosed on heroin and nearly died, drugs like heroin, cocaine, and alcohol can have lethal, short-term effects. By mimick ing a natural neurochemical in Henry's brain, heroin blocked the messages his brain uses to regulate his breathing. If it hadn't been for the paramedics, he would have stopped breathing. A heroin-blocking drug, the antagonist naloxone, which scientists originally developed in an effort to produce drugs that would relieve pain but not produce...

Measuring The Amount Of Energy The Brain Uses

Some diseases diminish the amount of energy that specific parts of the brain use. Some parts of the cerebral cortex in people with Alzheimer's disease use less energy than those same parts in normal people. Scientists have recently learned that parts of the cerebral cortex (although not exactly the same ones as in Alzheimer's disease) of cocaine addicts seem to use less energy than these same parts use in the brains of normal people. The decrease in energy use in Alzheimer's patients is the...

How Can A Drug That Produces Addiction Be A Medicine

Two issues confound comprehension when we try to understand the role of addictive drugs in medicine. First, how can a drug that causes the devastating behavioral changes of abuse and addiction be useful in medicine This question is often phrased as How can a bad drug be good It can be rephrased more usefully as How can we take advantage of a drug's medicinal benefits and at the same time protect ourselves from its threats Second, how do we determine which drugs have medical application and...

Routes Of Administration

People take drugs of abuse in a number of different ways they inhale them, inject them, absorb them through the mucous membranes of the nose, mouth, or other bodily orifices (did you ever have a rectal suppository ), or eat or drink them. People take some drugs only one way, that is, by only one specific route of administration. For example, people almost always drink alcohol, and they mostly smoke marijuana. But people take most other drugs by various routes at different times. For example,...

Sybils Treatment

Sybil has found her way to treatment because her addiction had begun to threaten her health, and her doctor intervened. Doctors often intervene with smokers who have contracted life-threatening lung, heart, or other diseases as a result of their addiction to nicotine and who must quit smoking if they want to survive. Sybil left the hospital and headed off for work, stopping at her pharmacy to fill Dr. McCloud's prescription for a nicotine patch and putting it on before she went to her office....

Why Drugs Can Change The Way Neurons Communicate

Synaptic transmission, which allows the brain to process information with great precision, flexibility, and subtlety, also leaves it vulnerable to drugs of abuse. That's because drugs of abuse, in effect, masquerade as neurotransmitters and interact with receptors and other components of the synapse. Drugs therefore interfere with normal synaptic transmission by introducing false messages or by changing the strength of real ones. Disrupting the transmission of information at the synapse is the...

Deconditioning

Addicts don't understand where their cravings come from (classical conditioning is unconscious learning), but all are likely to relapse if they don't learn how to recognize and work to neutralize these cravings. Some clinical researchers have been trying to decondition addicts by helping them identify and deal with the cues, or triggers, they unconsciously develop while they are addicted. Within the safety of the treatment center, these treatment providers expose and reexpose addicts to all of...

Neurotransmitters

At every synapse, the neuron changes its electrical signal into a chemical one. When that action potential reaches the neuron's axon terminals, it triggers the release of special chemicals that diffuse across the synapse to carry the message to the next neuron. Scientists call these chemical messengers neurotransmitters. Once a neuron receives a Figure 4.3 Neurons are like islands. Figure 4.3 Neurons are like islands. neurotransmitter's chemical message, it converts it into an electrical...

Changes At The Molecular Level

Scientists can see and measure changes in dendrites and axon terminals simply by looking under a microscope. But scientists also can see and measure even smaller, more subtle changes, which take place at the molecular level. These changes include alterations to certain receptors, components of second-messenger systems (see Chapter 4), and even alterations in some of the molecules that help give the neuron its shape. Even though the number of neurons, dendrites, and axon terminals remains...

Missing Clues About Effects of Other Drugs on the Brain

Scientists have not yet developed information about the neurobiological effects of the chronic use of drugs such as marijuana, LSD, and phencyclidine (PCP). So, this relatively short list of brain changes that could potentially underlie addiction and help us define it more precisely tells us three things. 1. We are just beginning to acquire knowledge about the neurobiological basis of addiction. It is a relatively new field that only attracted significant societal and scientific attention with...

Can Addiction Be Cured

Whether addiction can actually be cured is an open question. Twelve-step programs like AA are based on the premise that the changes induced by addiction are permanent and that addiction cannot be cured. That is why reexposure to the drug will lead to relapse into addiction. Even though proponents of the AA point of view do not believe that addiction can be cured, they do believe it can be treated successfully. Members are taught to avoid relapse by avoiding drugs. This is clearly the safest way...

One Reason Drugs Have Been Present Throughout History

We tend to lose sight of the reasons why drugs have been with us throughout recorded history. Our ancestors gathered certain flowers, leaves, and bark, cultivated various plants, and fermented fruits and grains because they needed the yield from these plant products to treat disease, relieve suffering, and enhance religious and social rituals. For almost all of history, most of the world had no effective drugs to treat any disease. Alcohol, cannabis, and opium were often the only drugs...