Consequences of Underage Drinking
Underage drinking, especially heavy drinking and frequent, heavy drink ing, is associated with numerous negative consequences. The consequences of alcohol use can be acute and immediate outcomes of a single episode of alcohol-impaired functioning, such as accidental death and injury, or they can be the accumulated and diverse effects of a chronic pattern of drinking, such as poor school performance and fractured relationships secondary to alcohol abuse and addiction. By ages 19 and 20, 70 percent of all drinkers engage in heavy drinking, suggesting that the majority of young people are at great risk of making poor decisions that have significant long-term consequences (Flewelling et al., 2004). But underage drinkers need not drink heavily to be at high risk of experiencing negative consequences. The crash risk associated with driving after drinking is higher for youths than for adults at all blood alcohol content (BAC) levels (Hingson and Kenkel, 2004). In other words, adolescents and young adults do not need to drink heavily to significantly increase their risk of negative consequences.
This chapter reviews some of the acute and chronic consequences of underage drinking. It covers such problems as drunk driving, as well as a range of other common consequences of acute impairment, such as violence. It also discusses long-term consequences of early drinking, including recent research on the possible effects of early onset of alcohol use on adolescent brain development.
Many adults may assume that the risks and potential consequences of underage drinking are more or less the same as they are for adults, but
research suggests that the dangers of youth drinking are magnified. In 2000, 36.6 percent of youths (under age 21) traffic fatalities involved alcohol, a rate slightly lower than the rate for adults (41.7 percent). However, when the denominator is the number of licensed drivers, drinking drivers under age 21 are involved in fatal crashes at twice the rate of adult drivers (National Highway Traffic Safety Administration, 2002a). Moreover, alcohol use among youths is strongly correlated with violence, risky sexual behavior, poor school performance, suicide, and other harmful behaviors (Hingson and Kenkel, 2004). College students are also significantly and negatively affected by their peer’s drinking (Wechsler, 1996; Wechsler et al., 2001a, 2001b, 2001c), including being assaulted, having one’s property damaged or experiencing an unwanted sexual advance. Recent research also suggests that adolescent drinking can inflict permanent damage on the developing brain (Brown and Tapert, 2004). And as noted in Chapter 2, early onset of alcohol use greatly increases the probability of adult alcohol dependence. In addition to the negative consequences to individual youth who drink, the costs of underage drinking to society—in lost lives, lost productivity, and increased health care costs—are substantial.
CONSEQUENCES OF ACUTE IMPAIRMENT
Alcohol impairs one’s decision-making capacity. As a result, young people who drink are more likely to engage in risk-taking behavior that can result in illness, injury, and death. Acute consequences of underage drinking include unintentional death and injury associated with driving or engaging in other risky tasks after drinking, homicide and violence, suicide attempts, sexual assault, risky sexual behavior, and vandalism and property damage. In addition, these consequences appear to be more severe for those who start drinking at a young age. Hingson and Kenkel (2004), report on a series of studies that controlled for history of alcohol dependency, frequency of heavy drinking, years of drinking, age, gender, race or ethnicity, history of cigarette smoking, and illicit drug use. These studies reveal that youth who started drinking before age 15, compared to those who waited until they were 21, were 12 times more likely to be unintentionally injured while under the influence of alcohol, 7 times more likely to be in a motor vehicle crash after drinking, and 10 times more likely to have been in a physical fight after drinking.
Drinking and Driving
The consequences of driving after drinking have received intense media attention and targeted policy responses. Laws have been passed to lower allowable blood alcohol content levels for underage drivers to near zero
(typically 0.02, compared with the adult limit of 0.08 or 0.10). Although alcohol-related youth motor vehicle fatalities have decreased substantially over the past decade or so, youth are still overrepresented in alcohol-related fatal crashes compared with the older population. In 2000, 69 percent of youths who died in alcohol-related traffic fatalities involved young drinking drivers. It remains a very serious issue with extreme consequences, not only for the young driver but also for innocent victims. While only 7 percent of licensed drivers in 2000 were aged 15 to 20, they represented approximately 13 percent of drivers involved in fatal crashes who had been drinking (National Highway Traffic Safety Administration, 2002b). According to Grunbaum et al. (2002), 38.3 percent of Latinos, 30.3 percent of whites, and 27.6 percent of African Americans in this age group rode with a driver who had been drinking alcohol. And 14.7 percent of whites, 13.1 percent of Latinos, and 7.7 percent of African Americans aged 15 to 20 admitted to driving a car after drinking alcohol.
Alcohol-related traffic fatalities constituted almost 37 percent of all fatal youth traffic fatalities (National Highway Traffic Safety Administration, 2002b). Youths who drive after drinking are more likely to be in a crash than youths who have not had a drink, and the crashes underage drinkers are involved in tend to be more severe than those of adults, resulting in a greater number of deaths and more serious injury. Underage drinkers present greater risks than adults when driving, even at lower BAC levels. More 19-year-olds died in alcohol-related crashes with relatively low BAC levels than any other age (National Highway Traffic Safety Administration, 2002b).
When young people drink and get into a car, they also tend to make poor decisions that bear on their safety. For example, young people who have been drinking are less likely to wear a safety belt. They are more likely to get in a car with an intoxicated driver: 41 percent of frequent heavy drinkers reported riding with an intoxicated driver, compared with only 14 percent of those who never drank (Hingson and Kenkel, 2004). In alcohol-related traffic crashes, there were three times more deaths among young people who were not wearing their seat belts than among those who were wearing them. In sum, alcohol-related crashes involving underage drinkers are more likely to result in death and serious injury than those involving other drivers.
Homicide, Suicide, and Unintentional Injuries
Alcohol is implicated in a large proportion of unintentional deaths and injuries caused by other forms of dangerous behavior than driving. In 1999, nearly 40 percent of people under age 21 who were victims of drownings, burns, and falls tested positive for alcohol. Youth constituted 7 percent of
nonfatal and 30 percent of fatal alcohol-related drownings and burns (Levy et al., 1999).
Drinking not only increases one’s risk of being involved in a traffic accident or suffering another unintentional injury, it is also implicated in deaths and injuries associated with violence and suicidal behavior. Frequent heavy alcohol use is associated with increased feelings of hopelessness, suicide ideation, and suicide attempts. Alcohol has been reported to be involved in 36 percent of homicides, 12 percent of male suicides, and 8 percent of female suicides involving people under 21—a total of about 1,500 homicides and 300 suicides in 2000. Homicide is the second leading cause of death for 15- to 24-year-olds (Centers for Disease Control and Prevention, 2001). By racial and ethnic group, deaths due to homicide for ages 15 to 24 are the leading cause of death for African Americans, second for Latinos, and fourth for whites. In that age group, suicide is the second leading cause of death for whites, third for Latinos, and third for African Americans (Anderson, 2002). Caetano and Clark (1998) report that the incidence of social consequences from drinking among Latinas is almost three times higher than for white females, despite generally lower rates of drinking.
According to Levy et al. (1999), individuals under the age of 21 commit 45 percent of rapes, 44 percent of robberies, and 37 percent of other assaults, and it is estimated that 50 percent of violent crime is alcohol-related (Harwood et al., 1998).1 A report by the National Center on Addiction and Substance Abuse (1994) found that on college campuses 95 percent of all violent crime and 90 percent of college rapes involve the use of alcohol by the assailant, victim, or both. Although it is difficult to disentangle alcohol use from other possible contributing factors, such as depression, emerging evidence demonstrates a causal link between alcohol and suicide (Light et al., 2003).
Sexual violence and unplanned and unprotected sexual activity constitute yet another set of alcohol-related problems. As reported in A Call to Action: Changing the Culture of Drinking at U.S. Colleges (National
Institute on Alcohol Abuse and Alcoholism [NIAAA], 2002) more than 70,000 students aged 18 to 24 are victims of alcohol-related sexual assault or date rape. Studies of date rape and sexual assault on college campuses suggest that alcohol use factors into the behavior of both assailants and victims. For example, Harrington and Leitenberg (1994) found that date rape victims who reported being at least “somewhat drunk” at the time of the assault believed that their assailants were also under the influence of alcohol. A study of assailants showed that 44 percent of the men had been drinking when they committed a sexual assault (Abbey et al., 1996). Given that many sexual assaults—especially acquaintance rape—are believed to be unreported, it is possible that alcohol figures into many more assaults than these studies indicate.
In addition to being more vulnerable to experiencing (or committing) sexual assault, young people who are drinking are also more likely to engage in risky sexual behavior. According to research by the Kaiser Family Foundation, young people are more likely to engage in consensual sexual activity after drinking and report that they “do more” sexually while using alcohol than they had planned. According to Strunin and Hingson (1992), 44 percent of sexually active teenagers report that they are more likely to have intercourse if they have been drinking. Based on analysis of 2001 Youth Risk Behavior Surveillance data, Grunbaum and colleagues (2002) report that 23.4 percent of white youth, 24.1 percent of Latino youth, and 17.8 percent of African American youth reported using alcohol or other drugs at the time of their last sexual intercourse.
Young people are less likely to use a condom if they have been drinking, which puts them at risk for unplanned pregnancies and contracting sexually transmitted diseases and HIV (the virus that causes AIDS). More disturbing still is that young people seem to be aware that using alcohol influences their decisions about sexual behavior: 29 percent of 15- to 17-year-olds and 37 percent of 18- to 24-year-olds said that alcohol or drugs influenced their decision to do something sexual. In other words, young people choose to drink even though they realize that alcohol affects their decision making and may cause them to engage in sexual behaviors they would not do while sober.
Early onset of alcohol use has also been associated with unplanned and unprotected sex. A college survey conducted by the Boston University School of Public Health showed that among drinkers, those who had their first drink before the age of 13 were twice as likely to have unplanned sex and more than twice as likely to have unprotected sex (Hingson and Kenkel, 2004).
Vandalism and Property Damage
Vandalism and property damage represent yet another set of consequences influenced by alcohol. Intoxicated youth are more likely to commit these acts regardless of their age, but vandalism and property damage are a particular problem on college campuses. Wechsler et al. (2002) report that about 11 percent of college students admitted to having damaged property while drinking. The cost of these behaviors is picked up by the college or by the local communities if the vandalism happens off campus.
A single episode of alcohol-impaired judgment can have immediate consequences (leading to death, injury, or arrest, for example) with long-term effects. In addition, heavy alcohol use at a young age has been implicated in long-term changes in the youths’ life prospects. Individuals who begin drinking before age 15 appear to be at greater risk for serious life-long problems (Hingson and Kenkel, 2004). For example, young people who begin drinking before age 15 are significantly more likely to develop alcohol dependence than those who begin drinking at older ages. Youth who begin drinking before the age of 15 have a 41 percent chance of future alcohol dependence, compared with a 10 percent chance for those who begin after the legal drinking age (Grant and Dawson, 1997). Some become dependent during adolescence.2 Analyses of the 1999 Harvard School of Public Health National College Alcohol Survey of students age 19 or older, after controlling for a variety of factors, found that the earlier they had first drunk to intoxication, the more likely they were to experience alcohol dependence and frequent heavy drinking in college (Gruber et al., 1996).
Frequent heavy use is associated with low self-esteem, depression (which is probably related to greater suicide attempts among underage drinkers), conduct disorders, antisocial behavior, dependency on other drugs and tobacco, and anxiety (Brown and Tapert, in press). Adolescents and college-age students who use alcohol have higher rates of academic problems and poor performance than nondrinkers. A Call to Action (NIAAA, 2002) noted that about 25 percent of college students report that using alcohol resulted in problematic consequences, such as missing classes, falling behind in school work, performing badly on papers and exams, and receiving lower grades overall.
Chronic health problems resulting from heavy alcohol use are generally not observed in adolescents because such effects take longer to accumulate. However, heavy drinking during adolescence, especially if this behavior is continued in adulthood, places a person at risk of such health problems as pancreatitis, hepatitis, liver cirrhosis, hypertension, and anemia. Chronic liver disease and cirrhosis among Latinos and American Indian and Alaskan natives are the sixth leading cause of death among these groups (Anderson, 2002). Recent research suggests that drinking during puberty may have deleterious effects on bone density development: for young women, failing to develop maximal bone density during adolescence puts them at risk later in life for osteoporosis.
Effects on the Adolescent Brain
New research on adolescent brain development suggests that early heavy alcohol use may also have negative effects on the actual physical development of brain structure (Brown and Tapert, 2004). Contrary to earlier beliefs, the brain continues to change physiologically well beyond childhood. Brain growth among infants and children is focused essentially on volume—creating as many brain cells with as many connections to other brain cells as possible. During adolescence, development shifts from producing a great number of neurons to creating efficient neural pathways, which occurs in two ways. First, the structure of neurons changes as they become encased by an insulating tissue (myelin) that helps to speed the movement of the electric impulses carried by brain cells. This change means that adults can relay information from one part of the brain to another more rapidly than can children. In adolescence, this myelination occurs predominantly in the frontal and prefrontal lobes, the part of the brain responsible for important functions such as planning, organization, and halting an impulse. The second change in brain development has to do with synaptic refinement, the process by which connections between brain cells are pruned and eliminated so that only the most efficient connections are used and maintained. Like myelination, synaptic refinement also contributes to increasing the speed and efficiency of transmitting information from one part of the brain to another, which in turn improves reaction time. Adolescent brain developments occur in areas of the brain critical for considering the consequences of actions and important for stress responses and managing drives (Spear, 2002).
Recent studies based on animal models suggest that alcohol use during adolescence may have deleterious effects on myelination and synaptic refinement. Rats that were given doses of alcohol in quantities and frequency that mimic the use of frequent heavy adolescent drinkers had problems with memory tasks (White et al., 2000). Another study showed that heavy alco-
hol use caused damage to the frontal regions of the brain (Crews et al., 2000).
New research using magnetic resonance imaging (MRI) technology to obtain a portrait of adolescent human brains support these animal studies, showing that the brain structure of youths with alcohol-use disorders is adversely affected. The hippocampus, which is responsible for forming new memories, was noticeably smaller in youth who abuse alcohol than in their nondrinking peers (De Bellis et al., 2000). Youth with alcohol-use disorders also performed worse on memory tests than nondrinkers, further suggesting that the structural difference in hippocampus size was affecting brain functioning. Neuropsychological studies also suggest that alcohol use during adolescence may have a direct effect on brain functioning: negative effects included decreased ability in planning and executive functioning, memory, spatial operations, and attention—all of which are important to academic performance and future functioning (Giancola and Mezzich, 2000; Brown et al., 2000; Tapert and Brown, 1999; Tapert et al., 2001).
THE CAUSATION QUESTION
Many consequences—both immediate and long-term—are correlated with youthful drinking. In the case of immediate consequences, drinking impairs one’s perceptual and motor skills, and this impairment clearly increases the risk of a car crash if one drives after drinking—a risk that is demonstrably higher for young drivers. Similarly, the disinhibiting effect of alcohol use impairs judgment and increases the risk of violence and unprotected sexual intercourse. In this sense, the causal link between alcohol use and the outcomes and problem behaviors just reviewed is not in doubt. The empirical evidence also shows a clear correlation between early drinking and problematic adult drinking and other related longer term problems: that is, the earlier that young people start drinking, the more likely they are to have problems in their adult lives.
However, these outcomes and behaviors may not be entirely attributable to alcohol. For example, some youths who have alcohol-related crashes or engage in alcohol-related violence or other risk-taking behavior may have been otherwise strongly predisposed to engage in problem behaviors of all sorts due to genetics, family circumstances, or other factors. Similarly, the higher rates of alcohol dependence, disease, and dysfunction among adults who began heavy drinking as youths may not be attributable to the early drinking per se. Some of these long-term outcomes are also consistent with the possibility that some individuals have a particular vulnerability to developing bad drinking habits and that one of the characteristics of these individuals is that they start drinking early. (For example, children of alco-
holics are more likely than children of nonalcoholics to start drinking during adolescence [NIAAA, 1997].)
Some of the strongest evidence of the causal role of alcohol in negative outcomes is derived from studies designed to assess the effects of policy interventions targeted on underage alcohol consumption. It is clear from these studies that reducing alcohol consumption among young people reduces such immediate outcomes as deaths, crime, and other consequences of impaired behavior. For example, research has shown that policies that affect alcohol availability, including excise tax rates and the minimum drinking age, have measurable effects on such outcomes as crime, highway fatalities, tobacco and drug use, and sexually transmitted diseases with greater availability associated with increases in these outcomes (Chaloupka, 2004; Chesson et al., 1997; Coate and Grossman, 1988; Cook, 1981; Cook and Moore, 1993a, 1993b; Cook and Tauchen, 1982, 1984; Kenkel, 2000; Ohsfeldt and Morrisey, 1997; Pacula, 1998; Ruhm, 1996; Saffer and Grossman, 1987; Wagenaar and Toomey, 2002). Given that the only plausible mechanisms by which such policies could affect these outcomes are through their effects on the volume and patterns of alcohol consumption, it is logical to conclude that alcohol consumption is indeed a causal agent for these outcomes.
In the case of long-term negative outcomes, the key question is whether reducing underage drinking would also reduce those outcomes. To the extent that individual vulnerability plays a large role, merely delaying the onset of drinking would not necessarily have much of an effect; the vulnerable people would eventually end up as problematic drinkers regardless of when they started. Moreover, many underage individuals who start heavy drinking in their late teens give it up as they reach their late 20s and 30s. The committee has carefully considered the evidence on this important issue—the extent to which early drinking causes later drinking problems, reduces them, or has no effect at all. Clearly predisposition and early alcohol use interact, and the effect of alcohol varies according to the degree of vulnerability of different individuals. However, notwithstanding the complexity of the inquiry, the committee concludes that the evidence establishes a prima facie case regarding the negative effects of early drinking on long-term welfare.
We think that prudent parents and a prudent society should assume, based on the current evidence, that underage drinking increases the risk of future drinking problems and contributes independently to the many deficits experienced by early drinkers over the course of their lives. However, additional research to further refine understanding of the interaction of the multiple interrelated factors on long-term outcomes is warranted.
It has become standard practice in formal assessments of the social burden of an illness or harmful activity to translate the resulting disability and death into dollar figures. Underage drinking is no exception. For example, a recent report concluded that the cost of alcohol use by youth was $53 billion in 1996, including $19 billion from traffic crashes and $29 billion from violent crime (Pacific Institute for Research and Evaluation [PIRE]). If the costs of other consequences—such as low academic performance or medical costs other than those associated with traffic crashes—were quantified, it is possible that the cost would be even higher. Since numbers of this sort are potentially important in setting public priorities, it is worth understanding some of the controversies and practical difficulties in making such estimates (see Chapter 4; Cook and Ludwig, 2000; Cook, 1991).
It is natural to measure the burden of underage drinking in terms of the incidence of various consequences. As we have seen, those consequences include violent death, disability, disease, reduced academic and occupational achievement, and property damage, among many others. Estimating the causal role that underage drinking plays in each of these outcomes is the very big and difficult challenge for epidemiologists. But even with reliable estimates for the contribution of underage drinking for each consequence, one would be left with the question of how to sum them up. A summary statistic is useful in assigning relative priority to this particular problem in comparison with all the other problems requiring public attention. A summary statistic quoted in dollar terms is particularly useful because it lends itself to comparison with the budget costs of policies to remediate the problem.
What question is to be answered by the estimate of social cost? Ultimately the question is something like the following: “How much would Americans’ overall standard of living improve if underage drinking were somehow eliminated?” In the PIRE study (1999) it is noted that the “cost” of underage drinking, based on the given assumptions, equaled $530 per year for every household in the United States; the suggestion is that eliminating underage drinking would be the equivalent of adding that amount to average household income.
Of course in practice there is no way to entirely eliminate underage drinking. But the total cost is nonetheless of some interest as a guide to how underage drinking can be compared with, say, cancer or illiteracy or terrorism in setting national priorities. The total is also useful to the extent that a
partial reduction in underage drinking may confer benefit in proportion to the total. Thus, the study suggests that a 10 percent reduction would be worth about $53 per household, or 10 percent of the total cost per household. Of course, a complete analysis would require an assessment of the costs of achieving the reduction as well as the benefit; if the 10 percent reduction is achieved through a set of programs that cost $10 billion, then the net gain per household would be just $43.
An Accounting Framework
There are two problems in doing this sort of accounting exercise well. First is the epidemiologist’s problem of discerning the actual consequences of eliminating (or reducing) underage drinking. What reduction would there be in highway crashes, crime, and school dropouts and in all the long-term effects of these events? All such consequences are the result of complex multicausal processes; knowing that there is alcohol involvement in some percentage of such cases leaves one far short of knowing the causal importance of drinking. A further complication is introduced by the realization that the actual effects of a reduction in underage drinking will depend not just on how much of a reduction is accomplished, but also on what sort of collateral consequences will occur. What effect will that intervention have on routine activities, such as weekend driving with friends, the use of other illicit drugs, or dating? The answers may be important in influencing the net consequences, which may well depend on the nature of an intervention to prevent or reduce underage drinking.
The second problem is to develop and implement a sound accounting system for translating outcomes into a measure of social burden. The choice of accounting rules in this context necessarily reflects decisions about deep issues in understanding the public good. Two specific issues are particularly thorny: whose preference should count in defining relevant consequences? Should the social cost computation include subjective losses or only production losses?
The presumption in our society is that the public good is the sum of individual preferences. A reasonable exception may be the preferences of teenagers, who tend to place too little emphasis on their long-term well-being and too much emphasis on pleasing their peers. That commonsense view of adolescent human nature, coupled with the fact that underage drinking is illegal, provides some justification for ignoring the pleasures of drinking as perceived by teens and accounting only for the harmful consequences.
Although few people think that the value of the life of someone killed or permanently disabled by a drunken teenager is limited to his or her lost earnings, that in fact has been the accounting rule used in the traditional
“cost of illness” method of accounting. That method stipulates that the social cost of a harmful activity or illness is the sum of direct costs (property damage, medical costs, and so forth) and indirect costs (lost productivity). Lost productivity has little relationship to the value that individuals and those who care about them place on the value of health and continued life.
A comprehensive accounting framework, then, should take account of both tangible and intangible costs associated with the consequences of underage drinking. The PIRE analysis cited above does just that. Of the $53 billion in costs estimated for 1996, all but $4 billion is the result of lost quality and quantity of life.3
While this report is not the place to explain the methods used to arrive at this result, we note that it is based on the underlying principle that (adult) preferences should guide the valuation. Those preferences are observed in a generic sense in a variety of settings and choices, where people make risky decisions. For example, wages for risky jobs tend to be higher than safe jobs requiring comparable skill and effort: the “risk premium” reflects the amount that workers must be compensated to take on additional risk, and thereby form a useful basis for assessing the average “value of life.” Note that what is being valued is not literally life itself, but rather a slight reduction in the probability of continued life. This valuation of small changes in safety is relevant for a forward-looking assessment. In assessing a proposed policy to reduce underage drinking, one does not know the identity of which lives will be saved; rather, the prospective accomplishment is a general reduction in risk for all, and that is what is to be valued.
The PIRE study is somewhat incomplete. For example, the study’s estimate does not include medical costs other than those associated with traffic crashes (Hingson and Kenkel, 2004). Perhaps most important is that it neglects the possibility that drinking by teens may cause mild brain damage and lead to impaired academic performance and early termination of schooling. It also takes no account of the possibility that underage drinking engenders a greater likelihood of subsequent problems with alcohol dependence and abuse. In these respects the $53 billion appears to be an underestimate of the social costs of underage drinking.
In sum, the cost of underage drinking to society is substantial. Society is affected by loss of young lives, lost productivity and significant health care costs and stands to gain from reductions in underage drinking. The committee concludes that the PIRE estimate of $53 billion, while perhaps somewhat low, is a reasonable starting point for assessing social costs.