Women were asked about type of ATS use ; frequency and route of use since their last visit; number of days of use in the past month; and use in the past five days, with specific questions including “today,” “yesterday,” and “two,” “three,” “four,” and “five” days ago. Urine toxicology testing was conducted to qualitatively screen for recent ATS, opiate, and cannabis use. Women were asked to void into prelabeled sterile collection cups in a private lavatory; the specimens were passed through a private window to the on site laboratory for testing. The test included four strips, which yielded positive results for amphetamine and/or methamphetamine if either exceeded 1000 ng/mL; for opiates if morphine in urine exceeded 2000 ng/mL; and for cannabis if the concentration 11-nor-Δ9-tetrahydrocanna binol-9-carboxylic acid exceeded 50 ng/mL. A positive amphetamine or methamphetamine screen was considered indicative of ATS use in the past 48 hours.Overall, results suggest high validity of self-reported ATS use among FSW when compared with urine toxicology screening. In almost all cases where women reported no ATS use in the past two days, negative urinalysis corroborated self-report. The majority of participants with positive urine tests reported ATS use during the same detection period. However, only 81% of participants who reported ATS use had positive urine tests. One possible explanation of the low positive predictive value is that women in the study actually used ATS but in such a small quantity that the urine tests failed to detect it. Since ATS is illegal and its purity is unknown,vertical outdoor farming some women could have used the less pure forms of ATS, which may not have been potent enough to be detected by urine testing. The NACD has reported that, among 151 pill samples of ATS tested, 25% of the samples had purities below 10%. Al though the proportion of women self-reporting ATS use was slightly higher than the urine test results , these rates are not inconsistent and are near perfect.

Other studies have documented higher self reported use compared with urinalysis results, leading to recommendations that multiple methods be used to assess drug use exposures. The high concordance between self-report and test results are suggestive of high internal validity of self-report of ATS in our study population. Some differences were seen in the performance of self report compared with urinalysis when examined by age, HIV status, and sex-work setting. Most notably, there was lower precision between positive self-report and urinalysis tests among younger women and among women working in entertainment or service settings. The lower PPV may relate to lower prevalence of ATS use among these subgroups. We have previously shown that women working in entertainment and service sec tors in Cambodia are less likely to use ATS than women working in brothels. Prevalence of ATS among younger women is slightly lower but not significantly so. Importantly, specificity was high overall, with subgroup analyses showing valid self-report of no ATS use in our sample. This is import ant for further studies of ATS exposure in this population, for public health surveillance, and potentially for intervention and implementation of drug prevention programs. The high validity of self-report may be associated with several factors. The women in this study were not reluctant to answer the survey questions or to take the test, as indicated by the high participation rate. This could be due, at least in part, to the fact that the participants were recruited by a known and trusted community-based agent, our collaborating partner , and were comfortable with the staff involved in data collection. Moreover, the women in the study knew that providing truthful responses about their drug use would not result in negative consequences or punitive action. This study had several limitations. Due to the small sample size and non-systematic sampling, our estimates lack precision and results may not be representative of all young women engaged in sex work in Phnom Penh or Cambodia. This is particularly true for the stratified analyses, where cell sizes were very small in some cases and prevalence of ATS was lower.

Poor recall may have contributed to some discordance, including the relatively low PPV found overall. Approximately one in five women incorrectly reported recent ATS use. Recall of ATS use could be affected by recent ATS use and its side effects, including sleep deprivation and confusion. It is unknown if this would result in over- or underestimating of self-report. Since women were all informed about the testing as part of the informed consent process and ongoing study-procedure education, some women may have over reported use for the periods about which they were queried. Moreover, urine toxicology tests are not perfectly accurate. Although the urinalysis test is widely accepted as a “gold standard” for substance use validation, exclusive reliance on such results does not necessarily improve validity because of problems with false negatives. Many studies comparing self-report, urine, and hair testing results suggest that hair analyses provide higher rates of recent drug use than can be detected by either urine tests or self reports. Various authors suggest multi-modal testing for the most accurate results. Despite these limitations, our results suggest a high level of concordance between self-reported ATS use and urine toxicology results in this group of women. Results indicate high prevalence of ATS use among FSW, who are also at elevated risk of HIV and other sexually transmit ted infections. There are few, if any, community-based options for ATS users in Cambodia. The finding that self report, especially specificity, is valid among young FSW is important because of potential utility in surveillance as well as drug prevention and intervention programs in this population. There is a significant need for evidence-based prevention and drug treatment resources in Cambodia, including potentially cognitive behavioral therapy, contingency management, and possibly new pharmacotherapies to reduce ATS use. The forthright self-reporting of drug use by women participating in this study shows that, in a safe and nonpunitive setting, disclosure of accurate drug use is possible. These findings, which are consistent with other studies showing high validity of self-reported drug use, may also be relevant to other vulnerable populations in Cambodia reported to have high rates of ATS use and who may also be in need of interventions, including children, young adults, and men who have sex with men.

Indeed, with escalating manufacture and use of ATS throughout Southeast and East Asia, and in consideration of the need for expanded surveillance of drug use to more accurately inform public health and policy responses, self reported use may be a reliable data collection method. For surveillance, research, and health-care settings, it is import ant that providers and others address drug-related health issues in a nondiscriminatory manner and without punitive consequences in order to accurately assess and effectively address health and safety issues in high-risk populations.Brain imaging research reveals that developing human brain systems undergo continuous biological and functional change, at multiple scales, well into adulthood. This long arc of development reflects a unique genome apparently selected to equip us with the capacity to develop a complex model of the world and revise it continuously through intelligent adaptation to the changing environment. It follows that variability in human phenotypes will emerge during development in part because of variation in individual genomes, but also, disproportionately,vertical aeroponic farming due to variation in physical and social environments and gene– environment interactions. Previous studies of the course of mental and substance use disorders, and also of academic and workforce disengagement, for example, have highlighted the pivotal role of ado lescence in the trajectories toward these functional outcomes. In studies of this important stage of development, multiple factors have been associated with adverse outcomes in youth, including genetic variation, attributes of the environment, individual experiences, and behavioral traits of the youth themselves. However, when these outcomes emerge gradually through dynamic interaction between gene and environment, retrospective reconstruction of the causal events is extremely challenging and can be misleading. Prospective, longitudinal studies of individuals developing in different environments have the potential to reveal the dynamics that lead to diverging trajectories; but only recently has it been possible to access non-invasively some of the factors known to play important roles in the outcomes, such as genomic and epigenetic variation, biologi cal development of the brain, and individual experiences and exposures. Now, however, with new noninvasive technologies in hand, and considering the gravity of the educational, health, and mental health problems we face as a society, human developmental scientists are obliged to create the data resources from which evidence-based models of emerging behavioral phenotypes can be constructed. Effective interventions to prevent or mitigate negative outcomes depend critically on such large-scale data and new models.Although it is not yet possible to predict risk for adverse behavioral and mental health outcomes in individuals accurately, the existing evidence implicates a number of plausible modifiers of risk, and leaves little doubt that environmental factors contributing to the disparities will be many and varied. Similarly, although there is strong evidence that genetic factors play a role, it is likely that the outcomes will be influenced by multiple genetic variants, most of which are likely to be of individually modest effect. In other words the genetic architecture of a risk phenotype is likely to be very complex. Finally, it is increasingly evident that the impact of environmental and experiential factors on specific developmental outcomes will differ as a function of the genetic variables, and may also differ as a function of culture and family structure. With this study, and others like it, we enter a new era in human behavioral neuroscience, which has been labeled population neuroscience. Since some outcomes of interest are relatively uncommon in the general population, it is necessary to observe a large number of developing youth in order to identify those factors and interactions that best distinguish these outcomes.

For these reasons, large scale, high-dimensional, longitudinal data resources are urgently needed by the scientific community, and these cannot be acquired without broad collaboration and careful harmonization of key data elements. The ABCD Study represents a major commitment by a consortium of researchers to create such a broad collaboration, focusing on the behaviorally critical, and biologically complex, period of development surrounding adolescence.The ABCD Study shares with the research community, as soon as is practicable, the entire evolving data resource, as a means of accelerating progress in the field. Unprocessed brain imaging data are shared almost continuously through the National Institute of Mental Health Data Archive, as part of the “fast-track” sharing arm of the study. In addition, updated, cumulative sets of curated data, along with workflows used to produce the derived data, are shared in annual versioned releases. ABCD is therefore a significant contributor to the data resources that support the new era of “big data” in biomedical research, and it complements most other studies by increasing the depth of phenotyping and adding important prospective developmental data. To ensure that the accumulated data are of acceptable quality, the ABCD consortium must establish robust data review procedures and closely monitor the quality of all types of data as well as ensure that the protocols provide both stable construct validity over time and necessary modifications as the cohort matures. Furthermore, the consortium attempts to adapt to emerging improvements in behavioral phenotyping methods that could enhance the study, and identify other relevant data streams, for example, of environmental factors, that can be integrated temporally and geographically with ongoing assessments of the participants. Thus, new data types and new computational workflows are expected to appear in future data releases. The ABCD Study, more than most similar studies, will push the envelope with an aggressive time line of data sharing and reduced barriers to access designed primarily to protect the privacy of participants and maintain records of the use of the data. Moreover, the sharing of associated workflows and specific algorithms will provide additional value to the larger scientific community beyond that of the data themselves. This new model will inevitably create challenges for conventional practices of scientists, reviewers, and editors, as multiple attempts to answer similar scientific questions with the same data will be under way almost simultaneously by independent investigators and groups.