Substance Use in Adolescents Chapter

Introduction

The use of intoxicating addictive substances by adolescents may lead to serious adverse cognitive, mental health, psychosocial, and medical consequences, as well as negatively impact normal adolescent brain development. Thus, substance use among adolescents is a major health concern.

One of the most important tasks of adolescence is called “identity formation,” ideally leading to a healthy, happy, and productive adulthood. There are numerous aspects of an individual's identity, including social, sexual, gender, moral, cultural, religious/spiritual, and racial/ethnic identity. In this chapter, the definition of adolescence will be that of the World Health Organization, which combines “adolescence” and “youth,” as ages 10–24 years of age. Adolescence is typically divided into three stages of development, based on physical/physiologic, psychosocial, and cognitive development. The average ages of these stages are: Early Adolescence 10–13 years; Middle Adolescence 14–17 years; and Late Adolescence (also called Young Adulthood or Emerging Adulthood) 18–24 years. It is in Middle Adolescence that adolescents significantly expand behavioral experimentation and engage in what are usually labeled as “exploratory” behaviors (healthy and positive) or “risk-taking” behaviors, which can often result in unhealthy or negative outcomes.

Many factors influence whether an adolescent tries addictive substances, including their availability within the neighborhood, community, and school, and whether the adolescent's friends are using them. A best friend who uses, or having a user peer group, is highly predictive of an individual using. The family environment is also important: violence, physical or emotional abuse, mental health issues, or substance use in the household increase the likelihood that the adolescent will use addictive substances (Adverse Childhood Experiences Score ). Genetic vulnerability also plays a role, with personality traits like poor impulse control or a high need for excitement; mental health conditions such as depression, anxiety, and attention deficit with hyperactivity disorder (ADHD). Beliefs such as that drugs are “cool” or harmless make it more likely that an adolescent will use drugs.

Adolescents meeting criteria for a severe substance use disorder, sometimes referred to as addiction, suggests that the individual has lost control over substance use. Addiction is a chronic, neurological condition associated with changes in the brain's reward center. Effective treatments, including medication and psychosocial support, are available, though addiction is not curable and long-term treatment is recommended.

Differences Between Risky Substance Use, Problem Use, and Addiction

Risky substance use in adolescence is different than problem use or having a substance use disorder (addiction). See Table 11.1 for specific definitions. Use of addictive substances by adolescents can lead them to engage in risky behaviors that they otherwise would not engage in. Examples of these risky behaviors include having unsafe sex (e.g., not using condoms when otherwise they would), which can result in an unintended pregnancy or acquiring sexually transmitted infections including Chlamydia, Gonorrhea, Human Papilloma Virus (genital warts and cervical cancer), Syphilis, and/or HIV; riding in a car as a passenger with an impaired driver, or driving when impaired, leading to injuries and accidents (including fatal motor vehicle accidents); “shooting up” with dirty needles, leading to HIV, Hepatitis C, or endocarditis; and getting into fights when under the influence of alcohol. Adolescents have a tendency to act impulsively (see brain development above), and risky substance use will often increase this impulsive behavior.

On the other hand, a hallmark of addiction is its compulsive aspect, which is not true of risky use. Risky use can lead to problem use or addiction, so again, early intervention is a key component of helping adolescents not become problem users or addicts.

Note that evidence for use of “soft drugs,” i.e., alcohol, marijuana, and tobacco, being “gateways” to the use of hard drugs (e.g., cocaine, heroin) is very weak. Although most hard drug users do start with use of soft drugs, the vast majority of soft drug users do not go on to hard drug use. The vast majority of users start with soft drugs because they are the most widely available and easily obtainable.

Adolescent Brain Development

Research on adolescent brain development has demonstrated that maturational brain changes, particularly myelination (the ability of brain nerves to communicate more quickly) and synaptic pruning (the ability of brain nerves to communicate more efficiently), occur throughout adolescence, well into the early-mid 20s. These changes are ultimately responsible for optimal neurocognitive performance. The last part of the brain to develop is the prefrontal cortex, which is responsible for executive function and impulse control. Use of addictive substances may alter the developing brain itself, in ways that are not yet fully understood but are different than usual development, leading to the adverse cognitive and other consequences noted above. Use of addictive substances—including the three most commonly used addictive substances by adolescents—nicotine, alcohol, and marijuana—may alter normal brain development, although not all studies show consistent findings. Various social determinants of health may also predispose adolescents to using addictive substances and in and of themselves significantly impact brain development, including childhood poverty, abuse, and neglect.

The younger an adolescent starts using addictive substances, whether nicotine, alcohol, or other drugs, the more likely problem use, or substance use disorder, will occur. Starting use at age 14 is a greater risk than starting at age 16, which is a greater risk than starting age 18, which is a greater risk than age 21. Threshold ages for decreasing risk seem to be ages 18 and 21. Thus, adolescents who do not start using addictive substances until age 18 are less likely to develop problem use than those who started before age 18, and those who do not use addictive substances until age 21 are at even less risk. Frequency of use is also correlated with problem use. Regular Users (defined as using 10–19 times/month) and Heavy Users (defined as using >= 20 times a month) are at particular risk of developing problem use.

Having a family history of a substance use disorder (SUD) may put an adolescent at higher risk, but otherwise it is difficult to predict who will develop problems. Thus, prevention and early intervention strategies are key to preventing the development of a SUD and all the associated adverse consequences.

Epidemiology

There are three longitudinal databases in the United States tracking adolescent substance use: Monitoring The Future (MTF), through the University of Michigan and the National Institute of Drug Abuse ; the Youth Risk Behavior Survey (YRBS), through individual states and the Centers for Disease Control and Prevention ; and the National Survey of Drug Use and Health (NSDUH), through the Substance Abuse and Mental Health Services Administration (SAMHSA). ²⁰ Looking at Monitoring The Future 2016, rates of current use (defined as using the substance at least once in the last 30 days) by 12th graders for the three most commonly used addictive substances are: alcohol 33.2%; marijuana 22.5%; nicotine (electronic vaporizers) 12.5%. Current users are at risk for becoming regular or heavy users and developing problem use, so this is an important intervention point to help adolescents cut back or discontinue use. For more detailed data on MTF current substance use rates nationally for 8th, 10th, and 12th graders, see Table 11.2 . Note that MTF has additional data on both lifetime and daily use rates.

TABLE 11.2

Current Substance Use

Adapted from Monitoring the Future (MTF) 2016.

For the 2016 NSDUH adolescent past month misuse of prescription pain relievers, tranquilizers, stimulants, and sedatives, see Table 11.3 .

TABLE 11.3

Past-month Misuse of Prescription Medications

Adapted from the National Survey of Drug Use and Health (NSDUH) 2016

Increasing use of marijuana, nicotine, and opioids is of major concern in the adolescent population and will be briefly discussed below.

Marijuana

Use of marijuana for both medical and recreational purposes is becoming more normalized. In 2017, 29 states and Washington, D.C. have legalized medical marijuana, and eight states have legalized recreational marijuana for adults ages 21 and older. Medical marijuana is portrayed as having numerous benefits, and recreational use is portrayed as benign. Concurrently, surveys have shown that adolescents' perception of possible harm of marijuana use is decreasing. One consequence of this may be more likelihood to drive under the influence, or ride with a driver under the influence, leading to more motor vehicle accidents and associated morbidity and mortality. It should be noted that there are no published clinical trials on the use of medical marijuana in children and adolescents, and that although occasional use of recreational marijuana by adults may not be harmful, no safe quantity has been established for adolescents. Frequent marijuana use throughout adolescence and into young adulthood appears linked to worsened cognitive performance. Earlier age of onset also appears to be associated with poorer neurocognitive outcomes that emerge by young adulthood, providing further support for the notion that the brain may be uniquely sensitive to frequent marijuana exposure during the adolescent phase of neurodevelopment. Additionally, there may be gender differences, with adolescent female users possibly more prone to anxiety and depression. Limited data in recreational marijuana states have not shown a significant increase in use in younger adolescents, though in Colorado use among college students has increased. More research and data are needed to know the impact of these legalization trends.

Counseling tips for parents and adolescents are included in a recently published American Academy of Pediatrics Clinical Report.

Nicotine

Electronic cigarettes (E-cigarettes or Electronic vaporizers) are electronic devices that vaporize liquid nicotine, and are often promoted for smoking cessation. However, they are sold in flavors such as bubble gum and cotton candy that are attractive to adolescents, who may initiate their “smoking careers” with these devices. E-cigarettes are now more commonly used by adolescents than traditional cigarettes and can be highly addictive. Use of nicotine products often precedes use of other addictive substances. Youth who smoke cigarettes are 5 times more likely than adolescent nonsmokers to use alcohol, 13 times more likely to use marijuana, and 7 times more likely to use cocaine or heroin.

Opioids

The opioid epidemic in the USA has significantly affected adolescents. Between 1991 and 2012, the rate of “nonmedical use” of opioid medication, i.e., use without a prescription or using more than prescribed, by adolescents more than doubled. NIDA reported in 2014 that 6% of teens had misused prescription opioids in the past year (∼2.4 million). The rate of opioid use disorders, including heroin addiction, has increased in parallel. NSDUH reported in 2014 that an estimated 467,000 adolescents (1.9%) aged 12 to 17 were current nonmedical users of pain relievers, and 16,000 were currently using heroin.