Summary of Key Findings

Age effects, secular trends, and cohort effects in substance use and related attitudes and beliefs.

from Monitoring the Future national survey results on drug use, 1975-2015: Overview, key findings on adolescent drug use

This piece was written by the principal investigators and staff of the Monitoring the Future project at the Institute for Social Research, the University of Michigan, under Research Grant R01 DA 001411 from the National Institute on Drug Abuse.

Introduction

Monitoring the Future (MTF) is a long-term study of American adolescents, college students, and adult high school graduates through age 55. It has been conducted annually by the University of Michigan’s Institute for Social Research since its inception in 1975 and is supported under a series of investigator-initiated, competitive research grants from the National Institute on Drug Abuse.

The need for a study such as MTF is clear. Substance use by American young people has proven to be a rapidly changing phenomenon, requiring frequent assessments and reassessments. Since the mid-1960s, when it burgeoned in the general youth population, illicit drug use has remained a major concern for the nation. Smoking, drinking, and illicit drug use are leading causes of morbidity and mortality during adolescence as well as later in life. How vigorously the nation responds to teenage substance use, how accurately it identifies the emerging substance abuse problems, and how well it comes to understand the effectiveness of policy and intervention efforts largely depend on the ongoing collection of valid and reliable data. MTF is uniquely designed to generate such data in order to provide an accurate picture of what is happening in this domain and why, and the study has served that function well for the past 41 years. Policy discussions in the scientific literature and media, in government, education, public health institutions, and elsewhere have been informed by the ready availability of extensive and consistently accurate information from the study relating to a large and ever-growing number of substances. Similarly, the work of organizations and agencies providing prevention and treatment services is informed by MTF.

The 2015 MTF survey involved about 44,900 8th-, 10th-, and 12th-grade students in 382 secondary schools nationwide. The first published results are presented in this report. Recent trends in the use of licit and illicit drugs are emphasized, as well as trends in the levels of perceived risk and personal disapproval associated with each drug. This project has shown these beliefs and attitudes to be particularly important in explaining trends in use. In addition, trends in the perceived availability of each drug are presented, which at times have proven important to explaining changes in usage levels for some drugs.

Summary of Key Findings

As an ongoing study, Monitoring the Future (MTF) is designed to detect age effects, secular trends, and cohort effects in substance use and related attitudes and beliefs. Age effects (changes with age seen across multiple class cohorts) are common during adolescence, and we typically find that use, as well as accepting attitudes and beliefs about use, increase across 8th, 10th, and 12th grades. When changes over time in substance use and related attitudes and beliefs are parallel across the three grades, they reflect secular trends, which are also common.

Cohort effects pertain to differences in substance use and related attitudes and behaviors among those born at different times that are maintained as the cohorts age. Such cohort effects sometimes drive changes in substance use prevalence at the population level. For example, much of the decline in the prevalence of U.S. cigarette smoking has its roots in youth cohorts that did not take up smoking and then continued to resist smoking as they aged into adulthood. As subsequent youth cohorts continued to avoid smoking and then grew older, these cohorts contributed to a decline in the population prevalence of smoking. Cohort effects can also act in the opposite direction, with newer cohorts taking up a substance and continuing to use it as they get older. One important contribution of the MTF study has been the specification of cohort effects that emerged starting in the early 1990s, when an increase in youth substance use occurred for many drugs. The recent increase in e-cigarette prevalence among teens may reflect the beginning of another cohort effect that could be observable among older age groups as the recent adolescent cohorts age.

MTF allows detection of cohort effects at an early age through comparison of substance use prevalence of 8th, 10th, and 12th graders relative to each other. Often 8th grade substance use is a bellwether, and year-to-year changes that are unique to 8th grade can signify an emerging increase or decrease in substance use at later ages with some time lag.

The analyses and associated tables that follow present substance use trends for all three grades separately, as well as trends in key attitudes, beliefs, and perceived availability. In a number of cases we provide insight into the age and cohort effects and secular trends that underlie trends in use and in key attitudes and beliefs. An additional set of tables provides an overview of drug use trends for the three grades combined (Tables 1–4). This information gives a summary of the general nature of historical trends over the last several years. Also, for trends that are in the same direction and magnitude across all three grades, these combined analyses provide greater statistical power to detect trends that are statistically significant. 

Declines in Use of a Number of Drugs in 2015

Perhaps the most striking finding in 2015 is that across the very broad spectrum of drugs (more than 50 classes and subclasses) none exhibited a statistically significant increase. 

Declining use in a number of licit and illicit substances is a main finding in 2015, as was the case in 2014. Cigarettes and alcohol continued to show significant declines, reaching their lowest levels in the history of the study. With regard to illicit drugs, annual prevalence declined for synthetic marijuana, heroin, MDMA (ecstasy, Molly), sedatives, and nonmedical use of any prescription drug. Annual prevalence of using any illicit drug remained essentially unchanged in all three grades in 2015; annual prevalence was 14.8%, 27.9%, and 38.6% in 8th, 10th, and 12th grades, respectively.

This stability in annual prevalence of using any illicit drug is primarily due to the fact that the annual prevalence of marijuana, which tends to drive the overall index, showed rather little change in 2015. For the three grades combined, annual prevalence of marijuana was down by just a non-significant 0.4 percentage points to 23.7%.

Although use of marijuana remained essentially unchanged in 2015, marijuana attitudes among students continued to move toward greater acceptance. Perceived risk of smoking marijuana regularly declined in all three grades, significantly so in 12th grade. In all three grades, the percentage seeing great risk of smoking marijuana regularly is at the lowest point ever recorded in the study – 58%, 43%, and 32% in grades 8, 10, and 12, respectively. Disapproval of people who smoke marijuana regularly was unchanged in 8th grade (at 82.2%), but declined slightly and nonsignificantly in 10th and 12th grades (to 74.3% and 70.7%, respectively). Although the 2015 levels are at or near historic lows, they still indicate relatively high levels of disapproval of smoking marijuana regularly.

Use of any illicit drug other than marijuana declined slightly in all three grades, but not significantly.

Annual prevalence in 2015 is 6%, 11%, and 15% in the three grades. 

Additional drugs with declining annual prevalence include synthetic marijuana (which in 2011 was the second most widely used drug after marijuana), MDMA (ecstasy, Molly), heroin, heroin use with a needle, and sedatives. 

The psychotherapeutic drugs warrant special attention, given that they now make up a significantly larger part of the overall U.S. drug problem than was true 10–15 years ago. This is in part because use increased for many prescription drugs over that period, and in part because use of a number of street drugs has declined substantially since the mid- to late-1990s. It seems likely that young people are less concerned about the dangers of using these prescription drugs outside of medical regimen because they are widely used for legitimate purposes. (Indeed, the low levels of perceived risk for sedatives and amphetamines observed among 12th graders illustrate this point.) Also, prescription psychotherapeutic drugs are now being advertised directly to the consumer, which implies that they are both widely used and safe to use. Fortunately, the use of most of these drugs has either leveled or begun to decline in the past few years. The proportion of 12th graders misusing any of these prescription drugs (i.e., amphetamines, sedatives, tranquilizers, or narcotics other than heroin) in the prior year continued to decline in 2015 (-1.0 %, not significant) to 12.9% which is down from a high of 17.1% in 2005. Amphetamine use without a doctor’s orders—currently the second most widely used class of illicit drugs after marijuana—continued a gradual decline in 2015 in all grades, though the one-year declines did not reach statistical significance. Use of narcotics other than heroin without a doctor’s orders (measured only in 12th grade) also continued a gradual decline begun after 2009, when annual prevalence was 9.2%; it was 5.4% after a non-significant decline of 0.7 percentage points in 2015.

Illicit Drugs Holding Steady in 2015

The use of a number of drugs showed little or no change from 2014 to 2015. These include hallucinogens, LSD specifically, hallucinogens other than LSD, inhalants, salvia, tranquilizers, cocaine, crack, powder cocaine, heroin use without a needle, methamphetamine, crystal methamphetamine, bath salts, OTC cough and cold medicines used to get high, and the club drugs GHB, rohypnol, and ketamine.

Tobacco and Alcohol Use

As in 2014, two main findings stand out for alcohol and tobacco use in 2015. First, cigarette smoking and alcohol use have continued their long declines and are now at the lowest levels in the history of the survey. Second, the new product of e-cigarettes, which has made rapid inroads among adolescents in recent years, has a 30-day prevalence higher than the prevalence of tobacco cigarette smoking, though its prevalence did not rise further in 2015.

One important new finding in 2015 is that very few of the students using electronic vaporizers are using to help them quit smoking regular cigarettes; only 5%, 7%, and 10% of the users in the three grades indicate this as one of the reasons for their use. More than half say they wanted “to experiment—see what it’s like” and around one-third gave the reason “because it tastes good.” (The liquid that is vaporized in these devices comes in hundreds of different flavors.6)

Declines in Tobacco and Alcohol Use

Thirty-day prevalence of cigarette use reached a peak in 1996 at grades 8 and 10, capping a rapid climb from the 1991 levels (when data were first gathered on these grades). Between 1996 and 2015, current smoking fell dramatically in these grades, by 83% and 79%, respectively. For 12th graders, peak 30-day prevalence occurred in 1997 at 37% and has shown a more modest decline since then. It is at 11% in 2015—a two-thirds decline since the peak—with a significant continuing decline in smoking prevalence in 2015. Because of the strong cohort effect that we have consistently observed for cigarette smoking, we have predicted use at 12th grade to continue to show declines, as the lighter-using cohorts of 8th and 10th graders become 12th graders; and, indeed, the largest (and significant) declines in both 2014 and 2015 were among the 12th graders.

Initiation of cigarette use also continues its long-term decline. Lifetime prevalence declined between 2014 and 2015 in all three grades: to 13% in 8th grade (-0.2, ns), to 20% in 10th grade (-2.6, s), and to 31% in 12th grade (-3.3, ss). The fact that fewer young people now initiate cigarette smoking is an important reason for the large declines in current use. The proportion of students who have ever tried cigarettes has fallen from peak levels reached in 1996 or 1997 by roughly threequarters, two-thirds, and one-half in the three grades, respectively.

Overall increases in perceived risk and disapproval appear to have contributed to the downturn in cigarette use. Perceived risk of smoking one or more packs of cigarettes per day increased substantially and steadily in all grades from 1995 through 2004, with 62%, 68%, and 74% of 8th, 10th, and 12th graders seeing great risk in 2004. Since then, changes have been small and uneven, and the corresponding figures in 2015 are only slightly higher, at 63%, 73%, and 76%. Disapproval of smoking one or more packs of cigarettes per day has increased somewhat steadily in all three grades since 1996. In 2015 disapproval stands at 89%, 88%, and 84% in grades 8, 10, and 12, respectively.

It seems likely that some of the attitudinal change surrounding cigarettes is attributable to the considerable adverse publicity aimed at the tobacco industry in the 1990s, as well as a reduction in cigarette advertising and an increase in antismoking campaigns reaching youth.

Various other attitudes toward smoking became more unfavorable during that interval as well, though some have since leveled off. For example, among 8th graders, the proportions saying that they “prefer to date people who don’t smoke” rose from 71% in 1996 to 81% by 2004, where it remained through 2014. Similar changes occurred in 10th and 12th grades. Thus, at the present time, smoking is likely to make an adolescent less attractive to the great majority of potential romantic agemates. However, most of the negative connotations of smoking and smokers have leveled off in the past few years. In addition to changes in attitudes and beliefs about smoking, price almost surely also played an important role in the decline in use. Cigarette prices rose appreciably in the late 1990s and early 2000s as cigarette companies tried to cover the costs of the 1998 Master Settlement Agreement, and as many states increased excise taxes on cigarettes. A significant increase in the federal tobacco tax passed in 2009 may have contributed to the continuation of the decline in use since then.

Cigarillos. One consequence of the rise in cigarette prices is that it may have shifted some adolescents to less expensive alternatives, like cigarillos (little or small cigars), which are taxed at a lower rate than cigarettes. Taking into account this form of smoking of tobacco raises the 30-day prevalence of students smoking tobacco—by three-fourths among 8th and 10th graders and by more than half among 12th graders—over what it would be if just cigarette smoking were counted. It does appear, however, that the prevalence of using small cigars is also in decline, with 16% of 12th graders in 2015 reporting any past-year use, down from 23% in 2010. Of note is the fact that the majority of users of small cigars in each grade smoke flavored ones.

Annual prevalence of smoking tobacco using a Hookah (water pipe) had been increasing steadily until 2014 among 12th graders (8th and 10th graders are not asked about this practice), but declined nonsignificantly by three percentage points to 20% in 2015.

Smokeless tobacco. From the mid-1990s to the early 2000s, smokeless tobacco use declined substantially, but a rebound in use developed from the mid-2000s through 2010. Since 2010, prevalence levels have declined modestly in all three grades. Perceived risk and disapproval appear to have played important roles in the earlier decline in smokeless tobacco use. In all three grades, perceived risk and disapproval rose fairly steadily from 1995 through 2004, accompanied by declines in use. However, there was not much change between 2004 and 2010, suggesting that other factors may have led to the increases in smokeless tobacco use during that time interval. These factors might include increased promotion of these products, a proliferation of types of smokeless tobacco products available, and increased restrictions on places where cigarette increased restrictions on places where cigarette smoking is permitted. The decline in smokeless tobacco use since 2010 (including a significant decline among 12th graders in 2015) may be attributable, at least in part, to the 2009 increase in federal taxes on tobacco. Perceived risk has not changed appreciably since 2010 at any grade level.

Alcohol remains the substance most widely used by today’s teenagers. Despite recent declines, two out of every three students (64%) have consumed alcohol (more than just a few sips) by the end of high school, and about a quarter (26%) have done so by 8th grade. In fact, nearly half (47%) of 12th graders and one in nine (11%) 8th graders in 2014 reported having been drunk at least once in their life.

Alcohol use began a substantial decline in the 1980s. To some degree, alcohol trends have tended to parallel the trends in illicit drug use. These include a modest increase in binge drinking (defined as having five or more drinks in a row at least once in the past two weeks) in the early to mid-1990s, though it was a proportionally smaller increase than was seen for cigarettes and most of the illicit drugs. Fortunately, binge drinking rates leveled off in the early 2000s, just about when the illicit drug rates began to turn around, and in 2002, a drop in drinking and drunkenness resumed in all grades. Gradual declines continued into 2015, which marked the lowest levels for alcohol use and drunkenness ever recorded by the survey in the three grades combined. (The 8th grade held steady in 2015.)

E-cigarettes

E-cigarette (or electronic vaporizer) use was assessed by MTF for the first time in 2014. Questions on frequency of e-cigarette use in the past 30 days as well as perceived risk of e-cigarettes were asked of 8th, 10th, and 12th graders. 

E-cigarettes now have the highest 30-day prevalence of all tobacco products, including regular cigarettes, at all three grade levels. For 2015, prevalence of ecigarette use was 9.5%, 14.0%, and 16.2% in 8th, 10th, and 12th grades, respectively, with no significant change from 2014. The corresponding prevalence for regular cigarette use was 3.6%, 6.3%, and 11.4%. Note that in 8th and 10th grades e-cigarette prevalence is more than twice the prevalence of regular cigarettes. As cohort effects in both cigarette and e-cigarette smoking work their way up the age spectrum, we may see this difference widening at 12th grade.

Substantially fewer students associate “great risk” with using e-cigarettes regularly as compared to smoking one or more packs of cigarettes per day. In 8th, 10th, and 12th grades, the percentage of students who perceive “great risk” in using e-cigarettes regularly is only 19%, 17%, and 16%, respectively, though the rate did rise some in all grades in 2015. The corresponding percentages for risk associated with smoking one or more packs of cigarettes a day is 63%, 73%, and 76%. E-cigarettes have a lower perceived risk for regular use than any other drug in the survey, including alcohol. One reason may be that only a minority of users say that on the most recent occasion of use there was nicotine in the inhaler. That is consistent with the fact that only a very few of them (from 5% to 10% of users) say they are using e-cigarettes to help them quit regular cigarette use. The most common reason given for use is “to see what it’s like”, while the second most common reason given is “because it tastes good.”

Resource

Johnston, L. D., O’Malley, P. M., Miech, R. A., Bachman, J. G., & Schulenberg, J. E. (2016). Monitoring the Future national survey results on drug use, 1975-2015: Overview, key findings on adolescent drug use. Ann Arbor: Institute for Social Research, The University of Michigan.