William T. O’Donohue, Lorraine T. Benuto and Lauren Woodward Tolle (eds.)Handbook of Adolescent Health Psychology201310.1007/978-1-4614-6633-8_6© Springer Science+Business Media New York 2013
The Epidemiology of Adolescent Health
(1)
School of Community Health Sciences, University of Nevada, Reno, Mailstop 274, Reno, NV 89557-0036, USA
Abstract
Adolescence is a time when many health problems are first identified and many health behaviors, both positive and negative, are established. This chapter reviews mortality and morbidity data as well as a range of behavioral health indicators in five major areas: (1) chronic disease, (2) mental health and suicide, (3) substance use, (4) sexual health, and (5) injury and violence. The most recent national data are summarized to describe trends over time and subpopulation differences in adolescent health indicators. The findings demonstrate that most adolescent health problems are preventable, highlighting the importance of early intervention to promote healthy behaviors and resilience.
Introduction
The transition from childhood to adulthood (adolescence) is a period of rapid physical, emotional, and developmental change. While most adolescents in the United States are healthy (Centers for Disease Control and Prevention [CDC] 2010a), adolescence is a time when many health problems are first identified. Rates of adolescent obesity, diabetes, and asthma have all increased dramatically over the past several decades signifying likely increases in adult chronic disease in the future (Perrin, Bloom, & Gortmaker, 2007). Furthermore, new population-level data suggests that the majority of mental disorders among adults emerge during adolescence (Merikangas et al., 2010). Adolescence is also a time when peer influence becomes very important, and many young people begin to experiment with alcohol, tobacco, and other drugs and explore their own sexuality. The behavioral risk taking that occurs during adolescence can profoundly impact immediate and long-term health outcomes.
To accurately describe the health of adolescents, it is important to review mortality and morbidity data as well as a range of behavioral health indicators. This chapter provides a summary of adolescent health epidemiology in five major areas: (1) chronic disease, (2) mental health and suicide, (3) substance use, (4) sexual health, and (5) injury and violence. While adolescence is generally defined as the period from puberty to maturity (typically 10–19 years) (National Research Council and Institute of Medicine, 2009), surveillance systems and national surveys use varying age groups. Therefore, the specific age range and definition of adolescence will be presented whenever possible. In addition, gender and racial and ethnic variation in adolescent health will be reported when the data sources allow for such comparison. This is critical as biological and behavioral risk factors differ for adolescent males and females and the US adolescent population is increasingly becoming more diverse (U.S. Census Bureau, 2011). Finally, it is important to note that most nationally representative data sources and ongoing behavioral surveillance systems do not assess sexual orientation and many measures of socioeconomic vulnerability. Therefore, the disproportionate burden of physical, mental, and behavioral health problems experienced by gay, lesbian, bisexual, and transgender adolescents and other subpopulations such as homeless adolescents, adolescents involved in foster care and juvenile justice systems, and recent immigrants is not adequately reflected.
Chronic Disease
The number of adolescents in the United States living with a chronic health condition has increased significantly in the past four decades (Perrin et al., 2007). Most of this growth reflects an increase in the incidence of asthma, obesity, and diabetes (Perrin et al., 2007). Adolescents living with chronic illness lead complicated lives and struggle with medication adherence, frequent medical visits, and internalized stress as a result of feeling different from other adolescents. Increasing rates of chronic health conditions among adolescents also imply increased rates in the US adult population in the next few decades. This will likely contribute to higher health care costs, decreased productivity of the workforce, and poor quality of life among affected individuals (Perrin et al., 2007).
Asthma
Asthma has more than doubled since the 1980s and is currently the leading chronic illness among adolescents (American Lung Association, 2010; Perrin et al., 2007). However, it is important to note that one of the primary surveys used to track asthma, the National Health Interview Survey (NHIS), was redesigned in 1997 and much of the difference in the pre-1997 and post-1997 rates may be attributable to changes in the questionnaire and rates have been relatively stable since 1997 (Akinbami, Moorman, Garbe, & Sondik, 2009). According to the 2009 National Health Interview Survey (NHIS), 17.2 % of adolescents (12–17 years) have ever been diagnosed with asthma and 11.2 % still have asthma (CDC, 2010a). Asthma rates among high school students in 2009 were consistent with NHIS findings with 22 % reporting a history of asthma and 10.8 % reporting current asthma (Eaton et al., 2010).
According to the NHIS, childhood asthma rates were consistently higher among males compared to females; however, at 16–17 years of age current asthma prevalence is similar for males and females (Akinbami et al., 2009) and the YRBS reported higher rates for females (Eaton et al., 2010). Black adolescents had higher lifetime and current asthma prevalence compared to those who are Hispanic or white (Eaton et al., 2010; CDC, 2010a). Furthermore, Akinbami and Schoendorf (2002) found that black adolescents were more likely to be hospitalized due to asthma and were four times more likely to die from asthma than Hispanic or white adolescents (Akinbami & Schoendorf, 2002). Income inequality appears to be associated with asthma rates with the highest lifetime and current rates reported among children and adolescents who relied on Medicaid and other forms of public insurance and those who were living in poverty (CDC, 2010a).
Asthma morbidity contributes to significant personal and societal costs. Children and adolescents have higher rates of asthma-related use of health care services than adults (Akinbami, Moorman & Liu, 2011). Asthma is also the most common cause of school absenteeism due to chronic conditions. In 2008, it was estimated that children and adolescents with asthma missed 10.5 million school days in a year and 5.5 % had an activity limitation due to asthma (Akinbami et al., 2011).
Obesity
Adolescent obesity (BMI for age at or above the 95th percentile) has more than tripled in the past 30 years. The prevalence of obesity among US adolescents aged 12–19 years increased from 5.0 % in 1980 to 18.1 % in 2008 (Ogden, Carroll, Curtin, Lamb, & Flegal, 2010) and in 2009, 12 % of high school students were classified as obese (Eaton et al., 2010).
Adolescent obesity disproportionately affects minority youth. The prevalence of obesity among high school students was higher among black and Hispanic than white students (Eaton et al., 2010). Similarly, the National Health and Nutrition Examination Survey (NHANES) found that in 2008 the prevalence of obesity was significantly higher among Mexican-American adolescent males than among non-Hispanic white adolescent males. Among girls, non-Hispanic black adolescents were significantly more likely to be obese compared with non-Hispanic white adolescents (Ogden et al., 2010). Bethell and colleagues (2010) also found that obesity rates were higher among publicly insured adolescents (10–17 years) compared to those who are privately insured (Bethell, Simpson, Stumbo, Carle, & Gombojav, 2010).
Specific causes for the increase in childhood obesity are not clearly established as longitudinal research in this area is limited and the factors associated with obesity are highly correlated (U.S Department of Health and Human Services, 2011). However, adolescent obesity is directly influenced by exercise and diet. The CDC recommends that young people (ages 6–17) participate in at least 60 min of physical activity daily (CDC, 2011a). However, in 2009, only 18 % of high school students had participated in at least 60 min per day of physical activity and only 33 % attended physical education class daily. Furthermore, a quarter (24.9 %) of students played video or computer games or used a computer for something that was not schoolwork for 3 or more hours per day and 32.8 % watched television 3 or more hours per day on an average school day. Only 22.3 % of high school students had eaten fruits and vegetables five or more times per day during the 7 days before the survey (Eaton et al., 2010).
Obese adolescents experience a number of physical and emotional health problems. One recent study found that 39 % of obese children and adolescents had two or more risk factors for cardiovascular disease such as high cholesterol, blood pressure, or lipid levels (Freedman, Zuguo, Srinivasan, Berenson, & Dietz, 2007). Adolescent obesity is also associated with increased risk for type 2 diabetes (Fagot-Campagna, Narayan, & Imperatore, 2001), sleep problems (Mallory, Fiser, & Jackson, 1989), and earlier maturation, particularly among females (Adar & Gorden-Larson, 2001). Furthermore, many obese adolescents suffer from poor self-esteem, depression, and low quality of life (Swartz & Puhl, 2003; Schwimmer, Burwinkle, & Varni, 2003; U.S. Surgeon General, 2001).
As obese adolescents age, they are at increased risk for becoming overweight or obese during adulthood (Patten et al., 2011; Supinya & Biro, 2011; Whitaker, Wright, Pepe, Seidel, & Dietz, 1997). For example, one study found that 80 % of adolescents (10–15) who were overweight were obese adults at age 25 (Whitaker et al., 1997). This contributes to adverse health outcomes during adulthood such as cardiovascular disease, hypertension, type 2 diabetes, and osteoarthritis (Reilly & Kelly, 2011; Adar & Gorden-Larson, 2001; U.S. Surgeon General, 2001; Dietz, 1998; Whittaker et al., 1997).
Diabetes
Historically, type 1 diabetes was the most common type of diabetes diagnosed among adolescents in the United States; however, in the last two decades, type 2 diabetes, formerly known as adult-onset diabetes, has increasingly been reported among adolescents (CDC, 2011b). The increase in adolescent type 2 diabetes is likely a result of dramatic increases in child and adolescent obesity and physical inactivity (CDC, 2011b). According to estimates from the largest surveillance study of diabetes among adolescents to date, in 2001 there were 121,509 adolescents (10–19 years) who had physician-diagnosed diabetes in the United States (2.80 cases per 1,000 adolescents) (SEARCH for Diabetes in Youth Study Group, 2006).
Overall, diabetes was more prevalent among females than males and black and white adolescents had the highest rates, followed by Hispanic, American Indian, and Asian and Pacific Islander adolescents. While type 1 diabetes accounted for most diagnosed diabetes cases, type 2 diabetes was more prevalent among minority populations. Type 2 diabetes accounted for 6 % of the white adolescent diabetes cases compared to 22 % of Hispanic cases, 33 % of black cases, 40 % of Asian and Pacific Islander cases, and 76 % of American Indian cases (SEARCH for Diabetes in Youth Study Group, 2006). The extremely high rate of type 2 diabetes found among American Indian adolescents in the SEARCH study supports previous research (Fagot-Campagna et al., 2000).
Adolescents with diabetes have an increased risk of developing health complications during adulthood such as heart disease, stroke, kidney disease, nervous system disease, and blindness (CDC, 2011b). Obesity is common among adolescents with type 2 diabetes and many adolescents with type 2 diabetes have multiple cardiovascular risk factors (Liu et al., 2010). Furthermore, adolescents with type 2 diabetes experience lower quality of life compared to those with type 1 diabetes (Naughton et al., 2008).
Mental Health and Suicide
Almost half of the US adolescent population (13–18) is affected by a mental health disorder (Merikangas et al., 2010). Due to a complex interaction of biological, cognitive, social, and environmental factors there are clear gender differences in adolescent mental health disorders. Anxiety, mood, and eating disorders are more common among female adolescents while behavioral disorders are more common among male adolescents (Zahn-Waxler, Shirtcliff, & Marceau, 2008). Poor mental health during adolescence may contribute to school dropout, family dysfunction, juvenile delinquency, substance use, risky sexual behaviors, and intentional and unintentional injuries (Glied & Pine, 2002; Angold et al., 1988; Ellickson, Saner, & McGuigan, 1997). Furthermore, approximately 8.9 billion dollars are spent on the treatment of child and adolescent mental health conditions annually (Soni, 2009).
Epidemiologic surveillance of mental health among adolescents has historically been limited to local and regional surveys using different methodologies, adult recall of mental health issues during adolescence, and national assessment of the symptoms of mental health disorders. However, the National Comorbidity Survey Replication (NCS-R) was recently enhanced to assess a broad range of DSM-IV disorders in a nationally representative sample of adolescents aged 13–18 years (NCS-A) (Merikangas, Avenevoli, Costello, Koretz, & Kessler, 2009). These results were first published in 2010 and represent the first national estimates of mental health disorders among adolescents in the United States. The adolescent mental health disorder estimates in the NCS-A are similar to those for adults in the NCS-R suggesting that the majority of disorders among adults emerge during adolescence (Merikangas et al., 2010).
Anxiety Disorders
There are several subtypes of anxiety disorders, including general anxiety, phobias, panic disorder, and post-traumatic stress disorder (PTSD). Chen and colleagues found that 40 % of adolescents (12–17 years) had symptoms of anxiety disorder (Chen, Killeya-Jones, & Vega, 2005) and the NCS-A demonstrated that nearly one third (31.9 %) of adolescents (13–18) suffered from an anxiety disorder based on DSM-IV classification (Merikangas et al., 2010).
According to the NCS-A, all anxiety disorder subtypes were more frequent in females compared to males, with the greatest gender difference found for PTSD. Overall, the prevalence of anxiety disorders was similar for different age groups, but there were several anxiety subtypes that demonstrated increasing prevalence with age (general anxiety, PTSD, panic disorder, and social phobia). It is also important to note that the median age of onset for anxiety was the earliest of any mental health disorder (6 years). Higher rates of anxiety disorders were found among black adolescents compared to white adolescents (Merikangas et al., 2010).
Mood Disorders
The NCS-A found that 14.3 % of adolescents (13–18) experienced mood disorders with 11.7 % meeting the criteria for major depressive disorder (MDD) or dysthymia (Merikangas et al., 2010). This supports findings from the National Survey on Drug Use and Health (NSDUH) demonstrating that 12.8 % of adolescents (12–17) reported at least one major depressive episode (MDE) in their lifetime and 7.9 % experienced a MDE during the past year (Substance Abuse and Mental Health Administration [SAMHSA], 2007). Only 38.9 % of adolescents who experienced MDE in the past year received treatment for depression (saw or talked to a medical doctor or other professional or used prescription medication) (SAMHSA, 2007).
Both the NCS-A and NSDUH found that females were approximately twice as likely to experience depression compared to males and prevalence of depression steadily increased with age (SAMHSA, 2007; Merikangas et al., 2010). According to the NCS-A, the median age of onset of mood disorders was 13 years (Merikangas et al., 2010), supporting prospective studies that demonstrated that the age of onset of depression is between 11 and 14 years (Lewinsohn, Rohde, & Seeley, 1998). Mood disorders were slightly higher among Hispanic adolescents compared to white adolescents in the NCS-A (Merikangas et al., 2010).
Behavior Disorders
According to NCS-A findings, 19.6 % of adolescents (13–18) had any behavior disorder, with 12.6 % meeting the diagnostic criteria for oppositional defiant disorder (ODD), 6.8 % for conduct disorder (CD), and 8.7 % for attention-deficit/hyperactivity disorder (ADHD) (Merikangas et al., 2010). The ADHD rates in the NCS-A confirm previous estimates from 2005 that found that 8.9 % of adolescents (12–17 years) had ever been told they had ADHD (Bloom, Dey, & Freeman, 2006).
According to the NCS-A, all conduct disorders were more prevalent among males compared to females with the greatest gender difference found for ADHD. The median age of onset for behavior disorders was 11 years and while the prevalence of ADHD and ODD remained relatively stable by age group, rates of CD increased as age increased. Racial/ethnic differences in behavioral disorders were not apparent (Merikangas et al., 2010)
Substance Use Disorders
Substance use is highly prevalent among adolescents and early initiation of substance use increases the likelihood of developing substance abuse or dependence during adolescence and into adulthood (Guttmannova et al., 2011). According to the NCS-A, 11.4 % of adolescents (13–18 years) met the criteria for a substance use disorder, with 8.9 % of adolescents diagnosed with drug abuse/dependence and 6.4 % with alcohol abuse/dependence (Merikangas et al., 2010). The median age of onset for substance abuse disorders was 15 years and substance use disorders increased with age with 22.3 % of adolescents 17–18 classified as having a substance use disorder. The NSDUH represents a younger adolescent population (12–17 years) and found that in 2009, 7 % of adolescents in the United States had abused or been dependent on alcohol or illicit drugs in the past year (SAMHSA, 2010).
Substance abuse disorders were somewhat higher among male adolescents in the NCS-A; however the prevalence of substance dependence or abuse among males was similar to females according to NSDUH findings (6.7 % vs. 7.4 %, respectively). Black adolescents in the NCI-A were less likely to have a substance abuse disorder compared to white adolescents (Merikangas et al., 2010).
Despite high rates of adolescent substance abuse disorders, receipt of treatment is low. In 2009, it was estimated that 1.8 million adolescents (7.2 %) needed treatment for a substance use disorder; however, only 8.4 % of those who needed treatment received it at an appropriate specialty clinic (hospitals [inpatient only], drug or alcohol rehabilitation facilities [inpatient or outpatient], or mental health centers) (SAMHSA, 2010).
Eating Disorders and Unhealthy Weight Loss Behaviors
According to NCS-A findings, lifetime prevalence of any eating disorder (anorexia nervosa, bulimia nervosa, and binge eating disorder) was 2.7 %. These disorders were twice as prevalent among females compared to males and increased with age (Merikangas et al., 2010). In addition to eating disorders, there is concern about unhealthy weight loss behaviors among adolescents such as fasting, vomiting, or taking laxatives. The 2009 YRBS found that nationwide, 10.6 % of high school students did not eat for 24 or more hours; 5 % had taken diet pills, powders, or liquids without a doctor’s advice; and 4 % had vomited or taken laxatives to lose weight or keep from gaining weight in the past 30 days.
Overall, the prevalence of these unhealthy weight loss behaviors was higher among female compared to male students; no clear racial or ethnic differences were identified (Eaton et al., 2010).
Suicide
In 2007, suicide was the third leading cause of death for adolescents (12–17 years) (National Center for Injury Prevention and Control, 2011). Furthermore, many youth think about or attempt suicide. In 2009, 13.8 % of high school students seriously considered attempting suicide, 10.9 % made a suicide plan, and 6.3 % attempted suicide at least one time in the past year (Eaton et al., 2010).
While suicide ideation and attempts were higher for females compared to males (Eaton et al., 2010), completion rates were higher for males (National Center for Injury Prevention & Control, 2011) who often use more lethal methods such as firearms (Moscicki, 2001). In 2008, completed suicide rates among American Indian/Alaska Native adolescents (12–17) were four times higher the rates of any other racial/ethnic group (National Center for Injury Prevention and Control, 2011). According to YRBS findings, attempted suicide was higher among black and Hispanic than white students and suicide ideation was higher among Hispanic than white and black students (Eaton et al., 2010). However, it is important to note that YRBS results for American Indian/Alaska Native students were not published.
Substance Use
Adolescent substance use is a leading cause of morbidity and mortality both during adolescence and into adulthood. While widespread public health intervention has contributed to a steady decline in adolescent alcohol, tobacco, and other drug use in the past two decades, rates have stabilized or increased in recent years. Early initiation of substance use is linked with greater likelihood of developing a substance use disorder (Guttmannova et al., 2011) and long-lasting neurophysiological changes in brain development (Ehlers & Criado, 2010; Mata et al., 2010). Substance use is associated with mental health disorders (Kandel et al., 1997), sexual risk taking (Connell et al., 2009), motor vehicle crashes (Dunlop & Romer, 2010), and violence (SAMHSA, 2010; Brady, Tschann, Pasch, Flores, & Ozer, 2008).
There are a number of ongoing substance use surveillance systems that monitor trends in adolescent substance use. The National Survey on Drug Use and Health (NSDUH) collects data on adolescents age 12–17 years; the Monitoring the Future (MTF) survey assesses 8th, 10th, and 12th grade students; and the Youth Risk Behavior Survey (YRBS) samples students in the 9th through 12th grades. Alcohol and drug use prevalence is consistently lower in the NSDUH compared to the MTF and the YRBS. Such differences are likely the result of sampling a younger population and differences in survey methodology, such as surveying in the home instead of at school (Harrison, 2001).
Alcohol Use
Both NSDUH and MTF findings demonstrate a steady decline in current (past month) alcohol use since the mid 1990s; however, prevalence did not change from 2008 to 2009 (SAMHSA, 2010; Johnston, O’Malley, Bachman, & Schulenberg, 2011). Substantial declines in binge drinking and age of initiation have also been observed (SAMHSA, 2010; Eaton et al., 2010). Despite such declines, alcohol remains the most commonly used drug among adolescents. In 2009, the prevalence of alcohol use in the past month ranged from 14.7 % according to the NSDUH to 41.8 % for high school students (SAMHSA, 2010; Eaton et al., 2010). Binge drinking (5 or more drinks in one sitting) in the past month ranged from 8.8 % (NSDUH) to 24.2 % (YRBS) (SAMHSA, 2010; Eaton et al., 2010). The YRBS also reported that 21.1 % of high school students began consuming alcohol before the age of 13 years (Eaton et al., 2010).
Overall, rates of current drinking, binge drinking, and initiation before the age of 13 were higher among males than females (SAMHSA, 2010; Eaton et al., 2010). The prevalence of current alcohol use and binge drinking was greatest for white adolescents, followed by Hispanic, and then black adolescents (Eaton et al., 2010; SAMHSA, 2010; Johnston et al., 2011). However, according to the YRBS, Hispanic adolescents were more likely to report drinking before the age of 13 (Eaton et al., 2010).
Tobacco Use
Current smoking among adolescents has also declined since the 1990s, but remained steady from 2008 to 2009 (Johnston et al., 2011; SAMHSA, 2010). In 2009, current cigarette use ranged from 8.9 % (NSDUH) to 19.5 % (YRBS) and daily cigarette use was between 2.1 % (NSDUH) and 11.2 % (YRBS) (SAMHSA, 2010; Eaton et al., 2010). According to the YRBS, 10.7 % of high school students have smoked a whole cigarette by the age of 13. Current smoking and smoking initiation were higher for males compared to females (SAMHSA, 2010; Eaton et al., 2010). Current smoking prevalence was highest among American Indian and Alaska Native adolescents followed by white, Hispanic, and black adolescents (SAMHSA, 2010; Eaton et al., 2010).
Despite declines in smokeless tobacco use since 1990s, both the MTF and NSDUH found that smokeless tobacco use increased in the last year measured (Johnston et al., 2011; SAMHSA, 2010). In 2009, current smokeless tobacco use ranged from 2.3 % (NSDUH) to 8.9 % (YRBS) (SAMHSA, 2010; Eaton et al., 2010). Current use of smokeless tobacco was greater among males than females (Eaton et al., 2010; SAMHSA, 2010; Johnston et al., 2011) and white adolescents, followed by Hispanic adolescents, and then black adolescents (Eaton et al., 2010).
Marijuana and Other Illicit Drug Use
Overall, the percentage of adolescents who reported current (past month) illicit drug use (with or without marijuana) gradually declined during the last decade, but has started to increase in the last couple of years (SAMHSA, 2010; Johnston et al., 2011). In 2009, the prevalence of current illicit drug use, including marijuana, ranged from 10 % (NSDUH) to 15.8 % (MTF) (SAMHSA, 2010; Johnston et al., 2011). Current marijuana use ranged from 7.3 % (NSDUH) to 20.8 % (YRBS) and 7.5 % of high school students reported using marijuana before the age of 13 (SAMHSA, 2010; Eaton et al., 2010). Current use of illicit drugs other than marijuana was lower, ranging from 1 % to 2.5 % for inhalants, 0.9 % to 1.3 % for hallucinogens, and 0.3 % to 1 % for cocaine according to NSDUH and MTF, respectively (SAMHSA, 2010; Johnston et al., 2011).
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