Video Abstract
Previously, we used Monitoring the Future (MTF) data to report on a trend from 1976 to 2014 of an increasing proportion of high school students abstaining from alcohol, cigarettes, marijuana, and other illicit substances and demonstrated different patterns for each substance.1 Here, we extend our findings through 2019 and examine the effects of vaping, which had not been measured in the MTF study before 2015.
Methods
We tracked trends in substance use and nonuse from 2015 to 2019 using MTF statistics.2 We then used data from the most recent available (2018) MTF 12th-grade public-use data file (n = 14 502) and employed the same methodology as in our original study to calculate the percentage of students in 2018 who had not used alcohol, cigarettes, marijuana, or illicit substances during their lifetime and the past 30 days (ie, abstainers). We compared these percentages to those reported for 2014. For the one-third of the students surveyed about vaping in 2018, we created binary indicators for lifetime and past-30-day use for each vaping category (nicotine, marijuana, “just flavoring”); students who reported no use during a specified interval were defined as vaping abstainers. We then calculated vaping-inclusive prevalence of lifetime (n = 4283) and past-month (n = 4249) abstinence from all substances. All prevalence calculations were performed by using SPSS version 23 software (IBM SPSS Statistics, IBM Corporation), with responses weighted to account for the MTF sampling methodology.
Results
The trends observed in the original study continued through 2019: each year an increasing percentage of high school seniors refrained from using alcohol, cigarettes, and illicit drugs, whereas the percentage using marijuana remained relatively unchanged. The trend line for vaping abstinence declined steeply (ie, rates of vaping increased sharply) during the 5 years these data have been collected (Fig 1, Table 1). The proportion of high school seniors reporting nonuse of all substances (excluding vaping) increased 5 percentage points between 2014 and 2018, reaching all-time highs of 30.7% and 57.6% for lifetime and past-30-day nonuse, respectively (Table 2).
Percentage of 12th-grade students reporting lifetime abstinence from specific drug classes, from all substances, and from vaping of any substances, MTF, 1976–2019.
Percentage of 12th-grade students reporting lifetime abstinence from specific drug classes, from all substances, and from vaping of any substances, MTF, 1976–2019.
Change in Prevalence (in Percentage) of Lifetime and Past-30-Day Abstinence From Alcohol, Cigarettes, Marijuana, Other Illicit Drugs, and Vaping Among 12th-Grade Students From 2015 to 2019 (Update Period), MTF
| Substance | 2015, % | 2019, % | Difference, % |
|---|---|---|---|
| Alcohol | |||
| Lifetime | 36.0 | 41.5 | 5.5 |
| Past 30 d | 64.7 | 70.7 | 6.0 |
| Cigarettes | |||
| Lifetime | 68.9 | 77.7 | 8.8 |
| Past 30 d | 88.6 | 94.3 | 5.7 |
| Marijuana | |||
| Lifetime | 55.3 | 56.3 | 1.0 |
| Past 30 d | 78.7 | 77.7 | −1.0 |
| Other illicit drugs | |||
| Lifetime | 78.9 | 81.6 | 2.7 |
| Past 30 d | 92.4 | 94.8 | 2.4 |
| Vaping | |||
| Lifetime | 64.5 | 54.4 | −10.1 |
| Past 30 d | 83.7 | 69.1 | −14.6 |
| Substance | 2015, % | 2019, % | Difference, % |
|---|---|---|---|
| Alcohol | |||
| Lifetime | 36.0 | 41.5 | 5.5 |
| Past 30 d | 64.7 | 70.7 | 6.0 |
| Cigarettes | |||
| Lifetime | 68.9 | 77.7 | 8.8 |
| Past 30 d | 88.6 | 94.3 | 5.7 |
| Marijuana | |||
| Lifetime | 55.3 | 56.3 | 1.0 |
| Past 30 d | 78.7 | 77.7 | −1.0 |
| Other illicit drugs | |||
| Lifetime | 78.9 | 81.6 | 2.7 |
| Past 30 d | 92.4 | 94.8 | 2.4 |
| Vaping | |||
| Lifetime | 64.5 | 54.4 | −10.1 |
| Past 30 d | 83.7 | 69.1 | −14.6 |
Change in Prevalence (in Percentage) of Lifetime and Past-30-Day Abstinence From all Substances Among 12th-Grade Students From 2014 to 2018, MTF
| 2014 (n = 11 674), % | 2018 (n = 13 468), % | Difference, % | |
|---|---|---|---|
| Lifetime | 25.7 | 30.7 | 5.0 |
| Past 30 d | 51.5 | 57.6 | 6.1 |
| 2014 (n = 11 674), % | 2018 (n = 13 468), % | Difference, % | |
|---|---|---|---|
| Lifetime | 25.7 | 30.7 | 5.0 |
| Past 30 d | 51.5 | 57.6 | 6.1 |
Including students who reported any vaping as substance users reduced lifetime and past-30-day abstinence rates by 2.0% and 5.4%, respectively. Decreases were relatively small because 12th-graders who vaped also used other substances in their lifetime (96%) or in the past 30 days (82%). Overall nonuse rates were significantly lower in the subsample of students who received MTF forms with vaping questions (27.3% vs 32.5% [P < .001], lifetime; 56.3% vs 58.2% [P < .05], past 30 days), driven primarily by greater alcohol use (36.0% vs 44.0%, lifetime; 67.9 vs 70.5%, past 30 days). Use rates of cigarettes, marijuana, and other drugs were not significantly different, nor were there differences in any measured demographics (Table 3).
Change in Prevalence (in Percentage) of Lifetime (n = 4283) and Past-30-Day (n = 4249) Abstinence From All Substances Among 12th-Grade Students in 2018 After Including Vaping, MTF
| Abstain From All Substances, % | Abstain From All Substances and From Vaping, % | Difference Due to Vaping, % | |
|---|---|---|---|
| Lifetime | 27.3 | 25.3 | −2.0 |
| Past 30 d | 56.3 | 50.9 | −5.4 |
| Abstain From All Substances, % | Abstain From All Substances and From Vaping, % | Difference Due to Vaping, % | |
|---|---|---|---|
| Lifetime | 27.3 | 25.3 | −2.0 |
| Past 30 d | 56.3 | 50.9 | −5.4 |
Discussion
An increasing proportion of high school seniors refrained from all substance use over the past 5 years, continuing a 44-year linear trend. Individual substances follow distinct courses; use rates for alcohol, cigarettes, and other illicit drugs all reached 44-year lows in 2019, whereas marijuana use rates remained stagnant. Nearly half of high school seniors vaped in their lifetime, although including vaping as substance use had only a minor impact on nonuse rates because the vast majority of students who vape also use other substances, confirming that initiating use of any substance dramatically increases the likelihood of using others.3
It is possible that the new phenomenon of vaping impacts substance nonuse differentially among younger students. Repeating these analyses for eighth- and 10th-grade students will be important for tracking the impact of vaping on youth of all ages. In the 2018 MTF sample, rates of substance use were higher among students who were asked about vaping. Survey versions were distributed randomly, although it appears that vaping questions were coincidentally more often distributed to students who had used alcohol. The percentage of change in abstinence rates might have been different if more students had been asked the vaping questions.
Conclusions
The proportion of high school seniors opting for substance nonuse continues to increase, but vaping and marijuana use could threaten this trend. We advocate for a simple message discouraging any substance use because of the increased vulnerability to harm during adolescence.4
Drs C. DuPont and R.L. DuPont and Ms Shea conceptualized and designed the study analyses and provided critical feedback of the manuscript; Dr Levy drafted the initial manuscript and reviewed and revised the manuscript; Dr Campbell conducted the initial analyses and reviewed and revised the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
FUNDING: Supported by grant 2019-04566 from the Charles Stewart Mott Foundation to the Institute for Behavior and Health, Inc.
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