The role of traumatic event history in non-medical use of prescription drugs among a nationally representative sample of US adolescents

Nonmedical use of prescription drugs (NMUPD) has been defined as “using a psychotherapeutic drug, even once, that was not prescribed for you, or that you took for only the experience or feeling it caused (SAMHSA, 2002).” According to recent estimates, over 2 million teens (aged 12 to 17 years; 9.3%) in the United States reported past year NMUPD, with teens accounting for over 15% of all past year prescription drug abusers (CASA, 2005). National estimates suggest that prevalence estimates of NMUPD among adolescents are second only to those for marijuana use in this population and that NMUPD (for pain relievers specifically) accounted for the largest number of first time illicit drug users between 2005 and 2006 (CASA, 2005; SAMHSA, 2006). In addition, rates of past-year NMUPD have steadily increased in the most recent decade for persons aged 12 and older, rising by more than 50% from 1991 to 2001 (Blanco et al., 2007; Zacny et al., 2003). Adolescent reports of NMUPD increased at a rate that was 2.6 times that of individuals over age 18, and more than half of new users in this timeframe were younger than age 18 (CASA, 2005; SAMHSA, 2006). Research suggests that, although the majority of students prescribed psychotherapeutic medications use them appropriately, teens' illegal access to prescription drugs often occurs when prescription drug users give away or sell their medications at school (McCabe, Boyd, & Young, 2007; Poulin, 2001). In order to better balance the value of appropriate prescription drug use versus the threat of misuse among adolescents, proper identification of populations at risk for misuse is noted as an essential next step in research on NMUPD (Compton & Volkow, 2006). Identification of risk factors for adolescent NMUPD is critical to inform prevention efforts. Data with population-based samples are limited to date, but several risk factors for adolescent NMUPD have been identified by previous research. Caucasian race, older age (i.e., late adolescence), and high rates of other substance use/abuse (including binge drinking, illicit drug use, and alcohol abuse) consistently have been associated with increased likelihood of NMUPD (CASA, 2005; McCabe, Teter, & Boyd, 2004; Sung, Richter, Vaughan, Johnson, & Thom, 2005; Wu, Pilowsky, & Patkar, 2008). National estimates find females to be significantly more likely to report NMUPD than males (CASA, 2005). However, research isolating some specific drug categories of NMUPD (e.g., stimulant use) has found that male adolescents are more likely to report non-medical use, suggesting that gender effects vary depending on the class of drugs (McCabe et al., 2004). With respect to psychosocial variables, lower family income, lower levels of parental involvement, and adolescent involvement in delinquent activities also have received some support as risk factors for adolescent NMUPD, whereas higher parental involvement has been indicated as a protective factor associated with decreased likelihood of NMUPD (Sung et al., 2005). Although some evidence suggests an association between NMUPD and history of mental health service utilization for emotional problems, there is a dearth of nationally representative data that examines specific mental health outcomes or major life events as potential correlates of increased NMUPD risk in adolescents (Sung et al., 2005). Only one research group has examined this area. Wu et al. (2008) used data from the 2005 National Survey on Drug Use and Health to provide a recent prevalence estimate for past-year (N=18,678) and lifetime (N=36,992) prescription pain reliever misuse, estimating that nearly 7% of adolescents misused pain relievers in the past-year and 10% had misused pain relievers in their lifetime. Several health indices were examined in association with NMUPD, but Wu and colleagues (2008) only investigated two mental health variables: service utilization and major depression. They found that mental health service utilization was positively associated with NMUPD among females, (OR=1.53) and major depressive episode (MDE) was significantly associated with prescription pain reliever abuse and dependence. Whereas these studies mark the first steps toward exploration of the relationship of NMUPD and mental health problems, to date, little is known about NMUPD in relation to mental health and traumatic event histories (e.g., abuse, violence exposure). Research with adult samples offers some insight into the association between NMUPD and PTSD, MDE, and traumatic event experiences. For example, studies have indicated an association between posttraumatic stress disorder (PTSD) and potentially traumatic experiences with NMUPD. Findings from a nationally representative sample of adult men and women support MDE as a risk associate of NMUPD; however, this study did not assess PTSD (Huang et al., 2006). A recent study using a nationally representative sample of household women (aged 18 to 86 years; N=3,001) examined both MDE and PTSD as potential risk factors of NMUPD and found that PTSD, but not MDE, was significantly associated with NMUPD in the final model (McCauley et al., 2009). McCauley and colleagues also found support for an association between potentially traumatic life events (i.e., drug-alcohol facilitated rape) and NMUPD. In sum, whereas a strong body of literature supports more broadly construed associations between traumatic experiences, PTSD, and other forms of substance abuse in adolescent populations, the extant research has yet to determine the nature of the associations between NMUPD, mental health variables, potentially traumatic experiences, and other forms of substance abuse (Kilpatrick et al., 2000; Kilpatrick et al., 2003). With respect to the association between PTSD, potentially traumatic experiences and substance abuse other than NMUPD, the extant literature has posited negative reinforcement models as a theoretical link between traumatic life experience and increased substance abuse. According to these models, individuals are thought to use substances as a method of avoiding or reducing (trauma-related) negative affect (e.g., self-medicating hypothesis; Baker, Piper, McCarthy, Majesikie, & Fiore, 2004). Whereas application of this model to the relation of PTSD and NMUPD has gained some support in adult samples, trends in NMUPD among adolescents have clearly differed from those of adults, and it is premature to assume that risk-factor findings with adult samples generalize to adolescent populations. The current study extends the literature by examining potential risk factors associated with lifetime NMUPD using a nationally representative sample of 3,614 US adolescents (aged 12 to 17 years). In addition to inclusion of demographic (age, race/ethnicity, gender, geographic area, family income) and substance use risk correlates (binge drinking, alcohol abuse, illicit drug use, and delinquent behavior), mental health variables (PTSD, MDE, and lifetime delinquency) and traumatic event exposure variables (physical assault, sexual assault, and witnessed violence) have been included as potential associates. Given previous support for an association between PTSD and substance use documented in adolescents and the association between PTSD and NMUPD found in samples of adult women, we predicted that PTSD would be associated with increased likelihood of lifetime NMUPD in adolescents. We also predicted that traumatic event exposure would be related to lifetime NMUPD.