Although both teen and parent hair analysis identified cocaine and opiate use at higher rates than reported, denial of cocaine use was higher for teens. Our low SES, high-risk urban teens self-reported marijuana, opiate, and cocaine use at rates similar to national anonymous surveys of black youth,18
yet biomarkers demonstrated that cocaine and opiate use was greater; 52 times greater for cocaine. Parent acknowledgment of their teen’s alcohol, tobacco, and marijuana use was also underreported compared with teen self-report.
Few teen studies compare biological measures with self-or parent-reported teen cocaine and opiate use. An addiction center that used urine testing found that the majority (64%) of teens who tested positive for marijuana admitted to use.20
In contrast, no teen admitted to cocaine use, and >70% of those who tested positive for opiates denied use. Mieczkowski et al21
found demographic site-specific variations in reports from adjudicated teens, with a lower incidence of cocainepositive hair (5.8%) in a sample of mainly white youths that included both boys and girls (St Petersburg, FL) compared with 55% in a 100% male sample of mostly black youths (Cleveland, OH). The 2 samples were similar in past 30-day use admission rates (Cleveland, 4.7; St Petersburg, 2.1). As far as we are aware, only 1 other nonclinical, nonadjudicated study compared teen cocaine self-report with biological assessment. 22
This non peer-reviewed study reports a low incidence of positive urine tests for cocaine (1.4%), but a 79% concordance between anonymous cocaine self-report and urine testing.22
An additional 0.7% admitted to cocaine use but had a negative urine sample; urine testing identifies only the most recent23–26
and possibly the heaviest cocaine users. Two additional differences between our report and this study is use of anonymous testing27
and the high environmental drug use in our study, which may also account for some interstudy differences (V.D.-B., L.M.C., J.H.H., et al, unpublished data, 2009).28
Identification of significant underreporting (25%–50%) of cocaine use from nonclinical, nonadjudicated adult samples is not new.29,30
Even higher rates of underreporting of cocaine,30,31
but not heroin32
have been identified in adult neighborhood studies. In contrast, highly accurate reports have been identified from adults beginning (89% for cocaine and 96% for heroin) but not after drug treatment programs (51%– 67%).33
Previous adult studies confirm that both black participants and residents of highly segregated neighborhoods, such as Detroit, are more likely to underreport drug use.34
Differences in SES and druguse social desirability have been related to the likelihood of adult study participants accurately selfreporting drug use.35,36
Researchers have hypothesized that for adults, the perceived threat of legal consequences from acknowledging illicit drug use may contribute to the relative poor sensitivity of self-report.37
Although some data from clinical and adjudicated samples exist, the rate of teen underreporting from a nonclinical, nonadjudicated sample has not been adequately addressed. The substantial discordance between self-reported teen, parent-reported teen drug use, and biomarker results in our cohort suggests that both teen- and parent-reported teen drug use, at least in a high-risk sample, can seriously underestimate teen illicit substance use. Although parents were 8 times more likely than teens to admit their own cocaine use, the adult caregivers in this study still significantly underreported their own cocaine and opiate use. It is possible that our teens may have felt more threatened by the potential for identification of their cocaine and opiate use than even their caregivers. However, inconsistent with this hypothesis was the lower rate of teen refusal of hair sampling compared with that of their parents.
Environmental contamination must be considered, although the commercial laboratory methods included pretest de-contamination of specimens and measurement of both cocaine and metabolites (ie, benzoylecgonine, norcocaine, and cocaethylene). Controversy remains about whether hair from cocaine-abstinent persons in chronic, casual environmental contact with cocaine is likely to test positive.37,38
Confidence in the validity of cocaine-positive hair in our study was bolstered by the presence of cocaine metabolites in hair, although this may not always effectively exclude contamination.37
We also confirmed prevalence rates for different sample batches and found that teen cocaine prevalence was consistent across time. Although we cannot fully exclude passive hair contamination, 39
home exposure cannot explain all cocaine-positive cases. Almost half of cocaine-positive teens were from households in which the parent was negative by report and bioassay. Although Huestis40
noted that individual results from hair analyses do not meet a judicial standard of proof, hair analysis is especially useful in aggregate data analysis and epidemiologic research.24
We note several limitations. Participation and quantity of hair collected, particularly for males, was problematic. We now offer a stipend for haircuts for teens whose hairstyle prevents obtaining an adequate specimen. Our findings are not based on a representative sample and may not generalize to drug use among other groups. Although recent data suggest that almost 12% of US teens live with at least 1 parent who depended on or abused alcohol or illicit drugs,41
in this cohort 23% of caregivers had Michigan Alcoholism Screening Test scores of ≥5, which suggests alcohol-related problems,42
and 11% had a Millon Clinical Multiaxial Inventory, Third Edition
, drug dependence scale score of ≥75, which suggests drug abuse. Earlier studies of adult marijuana users have suggested that a history of maternal heroin or cocaine use may increase the quantity of drug use.43
Thus, it is quite possible that the high incidence of parent drug use affected the prevalence of teen drug use in this study. However, teen denial of drug use, not the prevalence of teen drug use, was the focus of this report. Additional factors that may account for the high incidence of cocaine use among the teens and parents in our urban, low SES cohort include high levels of exposure to community drug use and community violence (V.D.-B., L.M.C., J.H.H., et al, unpublished data, 2009). Ensminger et al44
found similar lifetime rates of illicit drug abuse among their adult high-risk urban participants from a Chicago neighborhood >10 years ago.
Combined use of a biological measure self-report to assess teen and parent drug use in a large, nonclinical, nonadjudicated sample of teens, and the high rate of underreporting of teen cocaine and opiate use, are novel features of our study. These data clearly show significant underreporting of cocaine use by teens and parents, and of opiate use by teens, although participants were informed that a hair specimen would be obtained for drug testing. Even with the addition of parental suspicion of teen drug use, in this study simply asking adolescents and their parent if the teen was using illicit drug failed to identify at-risk youth.
Researchers, clinicians and policy makers should be cautioned that self-reported drug-use data, even in the presence of a “certificate of confidentiality,” substantially underestimate cocaine and opiate use among urban teens. Perceived social acceptability of reporting drug use, concern about the potential risks of drug-use admission, or perhaps anxiety that their parents might become aware of their drug use may all have accounted for teens’ preference to just say “I don’t.”