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Module 4.5: Substance Use and Abuse

While we all experience altered states of consciousness in the form of sleep on a regular basis, some people use drugs and other substances that result in altered states of consciousness as well. This section will present information relating to the use of various psychoactive drugs and problems associated with such use. This will be followed by brief descriptions of the effects of some of the more well-known drugs commonly used today.

Substance Use Disorders

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) is used by clinicians to diagnose individuals suffering from various psychological disorders. Drug use disorders are addictive disorders, and the criteria for specific substance (drug) use disorders are described in DSM-5. A person who has a substance use disorder often uses more of the substance than they originally intended to and continues to use that substance despite experiencing significant adverse consequences. In individuals diagnosed with a substance use disorder, there is a compulsive pattern of drug use that is often associated with both physical and psychological dependence.

Physical dependence involves changes in normal bodily functions that cause users to experience withdrawal from the drug if they stop using it. In contrast, a person who has psychological dependence has an emotional, rather than physical, need for the drug and may use the drug to relieve psychological distress. Tolerance is linked to physiological dependence, and it occurs when a person requires more and more drug to achieve effects previously experienced at lower doses. Tolerance can cause the user to increase the amount of drug used to a dangerous level—even to the point of overdose and death.

Drug withdrawal includes a variety of negative symptoms experienced when drug use is discontinued. These symptoms usually are opposite of the effects of the drug. In addition to withdrawal, many individuals who are diagnosed with substance use disorders will also develop tolerance to these substances. Psychological dependence, or drug craving, is a recent addition to the diagnostic criteria for substance use disorder in DSM-5. This is an important factor because we can develop tolerance and experience withdrawal from any number of drugs that we do not abuse. In other words, physical dependence in and of itself is of limited utility in determining whether or not someone has a substance use disorder.

Dig Deeper

Crack Cocaine


Figure 4.7 (credit: modification of work by U.S. Department of Justice)

Crack (Figure 4.7) is often considered to be more addictive than cocaine itself because it is smokable and reaches the brain very quickly. Crack is often less expensive than other forms of cocaine; therefore, it tends to be a more accessible drug for individuals from impoverished segments of society. During the 1980s, many drug laws were rewritten to punish crack users more severely than cocaine users. This led to discriminatory sentencing with low-income, inner-city minority populations receiving the harshest punishments. The wisdom of these laws has recently been called into question, especially given research that suggests crack may not be more addictive than other forms of cocaine, as previously thought.

Read this interesting newspaper article describing myths about crack cocaine.


Drug Categories

The effects of all psychoactive drugs occur through their interactions with our bodies' neurotransmitter systems. Many of these drugs, and their relationships, are shown in Figure 4.8. As you learned in Lesson 3, drugs can act as agonists or antagonists of a given neurotransmitter system. An agonist facilitates the activity of a neurotransmitter system, and antagonists impede neurotransmitter activity.


Figure 4.8 This figure illustrates various drug categories and overlap among them. (credit: modification of work by Derrick Snider)

Use the slideshow below to learn more about several categories of drugs. Click the arrows to move from one category to the next.

Alcohol and Other Depressants

A depressant is a psychoactive drug that tends to suppress central nervous system activity. Ethanol, which we commonly refer to as alcohol, is a depressant. Other depressants include barbiturates and benzodiazepines, which are often prescribed to treat anxiety and insomnia.

At low doses, alcohol use is associated with feelings of euphoria. As the dose increases, people report feeling sedated. Generally, alcohol is associated with decreases in reaction time and visual acuity, lowered levels of alertness, and reduction in behavioral control. With excessive alcohol use, a person might experience a complete loss of consciousness and/or difficulty remembering events that occurred during a period of intoxication. In addition, if a pregnant woman consumes alcohol, her infant may be born with a cluster of birth defects and symptoms collectively called fetal alcohol spectrum disorder (FASD) or fetal alcohol syndrome (FAS).

With repeated use of many central nervous system depressants, a person becomes physically dependent on the substance and will experience both tolerance and withdrawal. Psychological dependence on these drugs is also possible. Therefore, the abuse potential of central nervous system depressants is relatively high.

Drug withdrawal is usually an aversive experience, and it can be a life-threatening process in individuals who have a long history of very high doses of alcohol and/or barbiturates. This is of such concern that people who are trying to overcome addiction to these substances should only do so under medical supervision.

Stimulants

Stimulants are drugs that tend to increase overall levels of neural activity and often have abuse liability. Drugs in this category include cocaine, amphetamines (including methamphetamine), cathinones (i.e., bath salts), MDMA (ecstasy), nicotine, and caffeine.

Stimulant users seek a euphoric high. Repeated use of stimulants can cause physical symptoms that include nausea, elevated blood pressure, and increased heart rate. In addition, these drugs can cause feelings of anxiety, hallucinations, and paranoia.

Normal brain functioning is altered after repeated use of these drugs. For example, repeated use can lead to overall depletion among certain neurotransmitters, causing users to engage in compulsive use of these stimulant substances in part to try to reestablish normal levels of these neurotransmitters.

  • Cocaine can be taken in multiple ways. While many users snort cocaine, intravenous injection and ingestion are also common. The freebase version of cocaine, known as crack, is a potent, smokable version of the drug.
  • Methamphetamine is a type of amphetamine that can be made from ingredients that are readily available, making it easily accessible and relatively inexpensive.
  • Caffeine is probably the most commonly used drug in the world, but is not as potent as the other drugs found in this category. Generally, people use caffeine to maintain increased levels of alertness and arousal. Caffeine is found in many common medicines (such as weight loss drugs), beverages, foods, and even cosmetics. While it considered a relatively safe drug, high blood levels of caffeine can result in insomnia, agitation, muscle twitching, nausea, irregular heartbeat, and even death.
  • Nicotine is highly addictive, and the use of tobacco products is associated with increased risks of heart disease, stroke, and a variety of cancers. Nicotine is most commonly used in the form of tobacco products like cigarettes or chewing tobacco; therefore, there is a tremendous interest in developing effective smoking cessation techniques.
Opioids

An opioid is one of a category of drugs that includes heroin, morphine, methadone, and codeine. Opioids decrease pain. The human body naturally produces small quantities of opioid compounds that bind to opioid receptors, reducing pain and producing euphoria. Because they mimic this natural painkilling mechanism, opioid drugs have an extremely high potential for abuse. Abuse of prescription opioid medications is becoming a major concern worldwide.

Natural opioids, called opiates, are derivatives of opium, which is a naturally occurring compound found in the poppy plant. There are now several synthetic versions of opiate drugs (correctly called opioids) that have very potent painkilling effects, and they are often abused.

  • Heroin has been a major opioid drug of abuse historically. It can be snorted, smoked, or injected intravenously, and its use is associated with an initial feeling of euphoria followed by periods of agitation. Users who inject the drug often bear needle track marks on their arms and have an increased risk for contraction of blood borne diseases such as HIV.
  • Codeine is an opioid with relatively low potency. It is often prescribed for minor pain, and it is available over-the-counter in some countries. Like all opioids, codeine does have abuse potential.

Opioid withdrawal resembles a severe case of the flu. While opioid withdrawal can be extremely unpleasant, it is not life-threatening. Still, people experiencing opioid withdrawal may be given methadone to make withdrawal from the drug less difficult. Methadone is a synthetic opioid that is less euphorigenic than heroin and similar drugs. Methadone clinics help people who previously struggled with opioid addiction manage withdrawal symptoms through the use of methadone.

Hallucinogens

A hallucinogen is one of a class of drugs that results in profound alterations in sensory and perceptual experiences, like the psychedelic image to the right. In some cases, users experience vivid visual hallucinations. It is also common for these types of drugs to cause hallucinations of body sensations (e.g., feeling as if you are a giant) and a skewed perception of the passage of time.

As a group, hallucinogens are incredibly varied in terms of the neurotransmitter systems they affect. Mescaline and LSD are serotonin agonists, and PCP (angel dust) and ketamine (an animal anesthetic) act as antagonists of the NMDA glutamate receptor. In general, these drugs are not thought to possess the same sort of abuse potential as other classes of drugs discussed in this section.

Access a printable copy of this slideshowPDF 

Dig Deeper

Medical Marijuana


Figure 4.9 Medical marijuana shops are becoming more and more common in the United States. (credit: Laurie Avocado)

While the possession and use of marijuana is illegal in most states, it is now legal in Washington and Colorado to possess limited quantities of marijuana for recreational use (Figure 4.9). In contrast, medical marijuana use is now legal in nearly half of the United States and in the District of Columbia. Medical marijuana is marijuana that is prescribed by a doctor for the treatment of a health condition. For example, people who undergo chemotherapy will often be prescribed marijuana to stimulate their appetites and prevent excessive weight loss resulting from the side effects of chemotherapy treatment. Marijuana may also have some promise in the treatment of a variety of medical conditions.

While medical marijuana laws have been passed on a state-by-state basis, federal laws still classify this as an illicit substance, making conducting research on the potentially beneficial medicinal uses of marijuana problematic. There is quite a bit of controversy within the scientific community as to the extent to which marijuana might have medicinal benefits due to a lack of large-scale, controlled research. As a result, many scientists have urged the federal government to allow for relaxation of current marijuana laws and classifications in order to facilitate a more widespread study of the drug's effects.

Until recently, the United States Department of Justice routinely arrested people involved and seized marijuana used in medicinal settings. In the latter part of 2013, however, the United States Department of Justice issued statements indicating that they would not continue to challenge state medical marijuana laws. This shift in policy may be in response to the scientific community's recommendations and/or reflect changing public opinion regarding marijuana.

To learn more about some of the most commonly abused prescription and street drugs, check out the Commonly Abused Drugs Charts from the National Institute on Drug Abuse.

Check Your Knowledge

As you read your assignment for this lesson, pay close attention to the key terms and phrases PDF listed throughout the chapter. These terms and concepts are important to your understanding of the information provided in the lesson.