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A 21-year-old mother and her 4 children are being seen in a free clinic within a homeless shelter for various health reasons (Figure 246-1). The woman is currently clean and sober, but has a long history of cocaine use and addiction (Figure 246-2). Her children span the ages of 3 months to 5 years. She was recently living with her mother after the birth of her youngest child, but was kicked out of her mother's home when she went out to use cocaine once again. The patient gave written consent to the photograph, and when she was shown the image on the digital camera, she noted how depressed she looked. She asked for us to tell the viewers of this photograph that these can be the consequences of drug abuse—being depressed, homeless, and a single mom.

FIGURE 246-1

A cocaine-addicted mother with her children in a homeless shelter. Her drug addiction resulted in their homelessness. (Reproduced with permission from Richard P. Usatine, MD.)

FIGURE 246-2

Purified cocaine. (Reproduced with permission from U.S. Drug Enforcement Administration.)


Addiction occurs when substance use has altered brain function to an extent that an individual loses a degree of control over his or her behaviors. Addiction is an epigenetic phenomenon. Many genes influence the brain functions that affect behavior and genetic variants. These genes differ in their susceptibility to environmental conditions, which trigger the changes in brain circuitry and contribute to the development of addiction. Addiction must be recognized and treated as a chronic illness with an interprofessional team and social support. While opioid addiction has received an enormous amount of press lately for good reasons, there are many substances that, when used by some persons, lead to addictions. This chapter provides an overview of the disease of addiction. Some of the most addictive substances dealt with here and in the substance abuse section are tobacco, alcohol, marijuana, cocaine, methamphetamine, hallucinogens, and opioids.


  • An estimated 66.9 million Americans age 12 years or older were current users of a tobacco product in 2014. This represents 25.2% of the population in that age range. In addition, 55.2 million persons (20.8% of the population) were current cigarette smokers, 12.0 million (4.5%) smoked cigars, 8.7 million (3.3%) used smokeless tobacco, and 2.2 million (0.8%) smoked tobacco in pipes.1

  • An estimated 27.0 million Americans age 12 years or older were current illicit drug users in 2014. This represents 10.2% of the population in that age range.1

  • Marijuana was the most commonly used illicit drug (22.2 million users) (Figures 246-3 and 246-4). Marijuana is still the most widely used illicit drug, according to the 2014 ...

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