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. Author manuscript; available in PMC: 2020 Sep 1.
Published in final edited form as: Addict Behav. 2019 Apr 20;96:35–38. doi: 10.1016/j.addbeh.2019.04.015

Cocaine Use is Declining among Emerging Adults in the United States: Trends by College Enrollment

Kristin E Schneider 1, Julie K Johnson 2, Renee M Johnson 1
PMCID: PMC6579709  NIHMSID: NIHMS1528030  PMID: 31030177

Abstract

Background.

The difference in cocaine use between student and non-student emerging adults is not well understood, despite the longstanding assumption that college is protective against use.

Objective.

To describe trends in cocaine use among emerging adults by college enrollment.

Methods.

Using cross-sectional, nationally-representative data from the National Survey on Drug Use and Health (2002–2016), we estimated the prevalence of four cocaine use indicators by year among emerging adults (ages 18–22) and stratified by college enrollment. We tested for linear and quadratic trends over time.

Results.

From 2002–2016, 11.7% reported lifetime cocaine use, 5.8% reported past 12-month use, 1.7% reported past 30-day use, and 1% had a use disorder in the past 12-months. We observed significant linear decreases in all four use indicators over time (Lifetime: β = −0.20, Past 12-months: β = −0.17, Past 30-days: β = −0.22, Past 12-months disorder: β = −0.37). Students had lower rates of cocaine use than non-students, although prevalence estimates were more similar between groups for past 12-month (Students:5.3%, 95% CI:5.0–5.5; Non-students:6.3%, 95% CI:6.1–6.5) and past 30-day use (Students:1.6%, 95% CI:1.4–1.7; Non-students:1.8%, 95% CI:1.7–1.9) than for lifetime use (Students:9.4%, 95% CI:9.1–9.7; Non-students:13.8%, 95% CI:13.5–14.1).

Conclusions.

Cocaine use has declined among emerging adults since the early 2000s. The college environment appears compensate for early life differences in cocaine use risk between students and non-students, closing the gap between groups for recent indicators of cocaine use. Given the severe health consequences associated with cocaine use, more public health attention to this issue is needed.

Keywords: Cocaine, emerging adults, college, trends

1. Introduction

Cocaine is among the most harmful and most addictive drugs of abuse (Nutt et al., 2007; Nutt, King, & Phillips, 2010). The cardiovascular and neurological effects of cocaine, including heart attack, stroke, and seizures, are among the most serious and lethal (Afonso, Mohammad, & Thatai, 2007; Glauser & Queen, 2007; Rezkalla & Kloner, 2007; Schwartz, Rezkalla, & Kloner, 2010; Stankowski, Kloner, & Rezkalla, 2015). Other long-term harms of cocaine include neuropsychological deficits and mental health problems (Gawin, 1991; Jovanovski, Erb, & Zakzanis, 2005; Schwartz et al., 2010; Stankowski et al., 2015). Despite its serious harms, relatively little research has examined the epidemiology of cocaine use in recent decades, leading to gaps in our understanding of patterns of use and limited capacity for effective public health responses.

In the United States, the epidemiology of cocaine use varies by developmental period. While use is low among adults at large, an estimated 4–11% of emerging adults have used cocaine use in their lifetime (Schulenberg et al., 2018). Changes in use overtime also vary by age. One recent study suggested that cocaine use and use disorders increased by ~37% from 2002–2013 among adults generally (Kerridge, et al., 2019). Other studies suggest that adolescent cocaine use is rising (Johnson et al., 2015; Schneider et al., 2018). In contrast, some estimates indicate that past month cocaine use by 18–25 year olds has increased, while use among both younger and older subgroups declined (SAMHSA, 2018). Other estimates indicate use increased from 2011–2015 among 18–25 and 50+ year olds, but not other age groups (John & Wu, 2017). These mixed findings highlight the importance of examining cocaine use during specific developmental stages.

Emerging adulthood is the period from the late teenage years through the mid-twenties. (Arnett, 2005; Bachman et al., 2013). This developmental period can be broadly described as an “in-between” time, where individuals have more freedoms without many adult responsibilities (Arnett, 2007). Emerging adults are often exploring their identities in their new adult environments, without the supervision that was present in adolescence (Arnett, 2005; Schwartz, Côté, & Arnett, 2005; Schwartz et al., 2013). This period is characterized by instability and transitions in many aspects of life, including romantic relationships, education, and employment (Arnett, 2000). These elements can lead to high rates of substance use and risk-taking (Andrews & Westling, 2015). Substance use, including cocaine use, is more common in emerging adulthood than at any other point during the life span (Arnett, 2000, 2005; Chassin, Flora, & King, 2004).

Emerging adults who do not got to college experience a variety of psychosocial risk factors for drug use at higher rates than their college attending peers, like poverty, unemployment, and incarceration (Sum et al., 2009; Townsend, Flisher, & King, 2007). Meanwhile for student emerging adults, the college environment is a salient influence on substance use. Many facets of education are often associated with lower rates of substance use disorders (Stone et al., 2012). Alternatively, the college environment can be risky for substance use. College campuses combine large numbers of emerging adults with many new-found freedoms and little supervision, potentially generating an environment that promotes experimentation and risky drug use. For example, risky alcohol use, like heavy and binge drinking, is most prevalent among college students, due in part to the permissive use culture on campuses (Johnston et al., 2016; Wechsler et al., 1996; White & Hingson, 2013). The scarce literature suggests cocaine use is also high among college students (Kasperski et al., 2011). The MTF study found that emerging adults not enrolled full-time in college have double the prevalence (11.1% vs 5.3%) of lifetime cocaine use than their full-time college student peers, although estimates for past 12-month use were more similar (students:4.0%, other:6.5%) (Schulenberg et al., 2018). Epidemiologic research needs to clarify the specific effect of college enrollment on overall and current cocaine use among emerging adults.

2. Methods

2.1. National Survey on Drug Use and Health (NSDUH).

We used data from the 2002–2016 administrations of the NSDUH, a national survey conducted annually by the Substance Abuse and Mental Health Services Administration (SAMHSA, 2002–2016). The NSDUH provides nationally and state-wide representative estimates of substance use and mental health indicators in the US. Households are selected through multi-stage probability sampling. Researchers conduct in-person interviews with one or more individuals in each household. We restricted our sample to ages 18–22 (N=166,322, students: n=76,860, non-students: n=89,462), as the NSDUH only measures college enrollment for these ages.

2.2. Measures.

Cocaine Use.

We included four imputed cocaine use indicators in this study: (1) any lifetime cocaine use, (2) past 12-month cocaine use, (3) past 30-day cocaine use, and (4) past 12- month cocaine use disorder (abuse or dependence), based on DSM-IV-TR criteria (American Psychiatric Association, 2000).

College Enrollment.

College enrollment was categorized based on self-report, where participants who reported full-time or part-time enrollment were considered “students” and those who did not report enrollment were “non-students”.

2.3. Analyses.

We used Stata 14 for all analyses (StataCorp, 2013). Due to the complex survey design of the NSDUH, all estimates were weighted to ensure representativeness of the general US population and to account for survey year using Stata’s svy package. We estimated the prevalence of each cocaine use indicator by year for the overall sample and stratified by college enrollment. We tested for linear and quadratic trends for each use indicator over time overall and within each stratum. To assess trends, we fit a logistic regression model for each cocaine indicator and tested for main effects of year by estimating linear and quadratic trends using post estimation contrasts. To assess effect size, we constructed 95% confidence intervals with robust standard errors to reduce bias for all analyses.

3. Results

Trends in the prevalence of each cocaine use indictor are displayed in Figure 1. Supplemental Tables 1 and 2 contain the exact point estimates and confidence intervals for Figure 1.

Figure 1.

Figure 1.

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Trends in the Prevalence of Cocaine Use among Emerging Adults in the United States by College Enrollment (2002–2016).

3.1. Overall Prevalence and Trends

The prevalence of lifetime cocaine use for all years combined was 11.7% (95% CI: 11.5–11.9). Prevalence was highest in 2002 and declined until 2016 (linear trend: β=−0.20, p<0.001). This decline accelerated over time (quadratic trend: β=−0.03, p=0.004). The prevalence of past 12-month cocaine use was 5.8% (5.7–6.0) for all years combined. The prevalence increased slightly between 2002 and 2004, then declined until 2013, and finally increased slightly until 2016. We observed a significant decline in the prevalence of past 12-month use (linear: β=−0.17, p<0.001) that decelerated over the study period (quadratic: β=0.03, p=0.03). The prevalence of past 30-day cocaine use was 1.7% (95% CI 1.6–1.8) for all years combined. Use was highest in 2005 and lowest in 2009. We observed a significant linear decline over the study period (β=−0.22, p<0.001), but no quadratic trend (β=0.04, p=0.13). One percent (95% CI 0.9–1.0) of emerging adults reported a cocaine use disorder in the past 12 months. The prevalence of use disorders was highest in 2004 and lowest in 2014. We observed a significant linear decline (β=−0.37, p<0.001), but no quadratic trend (β=−0.04, p=0.31).

3.2. Trends by College Enrollment

For all years combined, the prevalence of lifetime cocaine use was 9.4% (95% CI 9.1–9.7) for students and 13.8% (95% CI 13.5–14.1) for non-students. There were statistically significant declines over the study period for both students (β=−0.17, p<0.001) and non-students (β=−0.22, p<0.001). This downward trend accelerated only for non-students (β=−0.07, p<0.001). The gap between students and non-students closed over time, there was just a 1.1 percentage point difference by college enrollment in 2016. Overall, 5.3% (95% CI 5.0–5.5) of students and 6.3% (95% CI 6.1–6.5) of non-students used cocaine in the past 12 months. There were significant, negative linear trends for both students (β=−0.14, p<0.001) and non-students (β=−0.20, p<0.001). This decline slowed only amongst students over time (β=0.09, p<0.001). The prevalence of past 30-day cocaine use, across years, was 1.6% (95% CI 1.4–1.7) for students and 1.8% (95% CI 1.7–1.9) for non-students. There were significant linear declines in past 30-day use for both students (β=−0.16, p<0.001) and non-students (β=−0.27, p<0.001). Again, this decline slowed among students (β=0.10, p=0.02), but not non-students. Across years, 0.7% (95% CI 0.6–0.8) of students and 1.2% (95% CI 1.1–1.3) of non-students had a cocaine use disorder in the past 12-months. Past 12-month cocaine use disorders also declined significantly over time for both students (β=−0.36, p<0.001) and non-students (β=−0.37, p<0.001). There were no significant quadratic trends in use disorders for either group (students: β=−0.01, p=0.87; non-students: (β=−0.08, p=0.09).

4. Discussion

Emerging adulthood is a high-risk developmental period for substance use, but little research has examined the role of college on use. We examined trends in cocaine use among emerging adults in the US over the past 15 years and found that cocaine use and use disorders have declined since the early 2000s and that non-student/student differences became smaller over time. Although this is positive news, continuation of this trend cannot be taken for granted, especially given the deceleration of this trend particularly among college students. It should also be noted that our findings contrast with some existing literature, suggesting that cocaine use has increased among 18–25 year olds (John & Wu, 2017; Substance Abuse and Mental Health Services Administration, 2018). This contrast may be due to ages 23–25, not included in our study, having different use trends than their younger peers.

College enrollment may confer risk for cocaine use. Non-students had higher rates of lifetime use than students, but the groups were more similar for past 12-month and 30-day use. Our estimates for past 12-month cocaine use for student and non-student emerging adults were similar to reported by the MTF study, despite different methodologies (Schulenberg et al., 2018). Researchers also observed a decrease in the gap between students and non-students when comparing lifetime and past year use, similar to the results of our present study (Schulenberg et al., 2018). One explanation for these results is that precollege factors that increase risk for cocaine use differ between those who do and do not eventually attend college. In other words, emerging adults who become students and non-students likely have different early life exposures that determine both their college enrollment and adult cocaine use. Some examples of such that have been previously identified include poverty, family functioning, and negative peer associations, among others (Townsend, Flisher, & King, 2007). The difference between students and non-students decreased with recency of reported use, suggesting that the college environment may close the baseline gap in risk for cocaine use between students and non- students. Follow up studies are needed to explicitly test this hypothesis.

In this study, we did not differentiate between full and part time students, who may differ in terms of cocaine use and other life circumstances. We were also limited by the fact that the NSDUH only measures college enrollment for age 18–22, which may exclude some students. Despite these limitations, this study is an important step in clearly defining the public health problem of cocaine use among emerging adults in the present era. Future studies should further this line of inquiry by examining the effect of key elements of the college environment on cocaine use. Potential aspects of college that may be relevant to cocaine use include residing in a shared student accommodation and the type of college (traditional university, community college, trade school, etc.).

We examined the epidemiology of cocaine use among emerging adults over 15 years. Since the early 2000s, cocaine use has declined amongst emerging adults. Despite this decline, cocaine use remains prevalent in this age group. Furthermore, our results suggest that the college environment is potentially risky for past 30-day and past 12-month cocaine use, especially in recent years. Use disorders were more common amongst non-students, suggesting that they may be at increased risk for worse cocaine use related outcomes. More attention must be paid to cocaine use among emerging adults and interventions should consider the differences in use between students and non-students. Potential interventions to address cocaine use include screening/brief intervention in student health centers and expanded treatment availability for those not enrolled in school.

Supplementary Material

1

Highlights.

  • Cocaine use declined among emerging adults in the United States between 2002–2016.

  • Non-students had higher rates of lifetime cocaine use than students.

  • Students and non-students had more similar rates of past 12-month and 30-day use.

  • Rates of cocaine use converged between the groups, as students’ declines decelerated.

Funding.

This research was supported by the National Institute on Drug Abuse [grant numbers 5T32DA007292-25 (KES and JKJ supported, Co-PIs: Johnson and Maher), K01DA031738 (PI: RMJ)]. The study sponsor had no role in determining study design; data collection, analysis, or interpretation; writing the report; or the decision to submit the report for publication.

Footnotes

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Conflicts of Interest: None.

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