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Purpose of review To provide an accessible overview of some of the most recent trends in the application of machine learning to the field of substance use disorders and their implications for future research and practice. Recent findings Machine-learning (ML) techniques have recently been applied to substance use disorder (SUD) data for multiple predictive applications including detecting current abuse, assessing future risk and predicting treatment success. These models cover a wide range of machine-learning techniques and data types including physiological measures, longitudinal surveys, treatment outcomes, national surveys, medical records and social media. Summary The application of machine-learning models to substance use disorder data shows significant promise, with some use cases and data types showing high predictive accuracy, particularly for models of physiological and behavioral measures for predicting current substance use, portending potential clinical diagnostic applications; however, these results are uneven, with some models performing poorly or at chance, a limitation likely reflecting insufficient data and/or weak validation methods. The field will likely benefit from larger and more multimodal datasets, greater standardization of data recording and rigorous testing protocols as well as greater use of modern deep neural network models applied to multimodal unstructured datasets.

Background: The use of ketamine, a controlled dissociative anesthetic, has become more widespread in recent years with recreational/nonmedical use increasing and ketamine becoming more widely available in clinics to treat depression. Aims: We examined recent trends in adverse effects related to ketamine use. Methods: US National Poison Control data were examined, focusing on ketamine exposures among those aged ⩾13 between 2019 and 2021 ( n = 758). We examined quarterly trends in exposure and delineated correlates of patients experiencing a major adverse effect or death. Results: The number of reported exposures increased 81.1% from 2019 Quarter 1 through 2021 Quarter 4, from 37 to 67 ( p = 0.018). The majority of patients were male (57.1%), and the plurality of cases involved intentional misuse or “abuse” (39.5%), followed by suspected suicide attempt (19.7%) and unintentional exposure (18.9%). A fifth (19.6%) experienced a major adverse effect or death. A third (33.4%) co-used other drugs; the drugs most commonly co-used were benzodiazepines (14.6%), alcohol (10.3%), and opioids (8.7%). Co-use of gamma-hydroxybutyrate (GHB; adjusted prevalence ratio (aPR) = 3.43, 95% confidence interval (CI): 1.57–7.46) and opioids (aPR = 2.44, 95% CI: 1.46–4.08) was associated with increased risk for a major adverse effect or death, as was injection-only administration (aPR = 2.68, 95% CI: 1.21–5.92). Conclusions: Although still rare, poisonings involving ketamine have increased in recent years. Polydrug use—particularly with opioids or GHB—appears to be a particular risk factor for more serious adverse effects. As prevalence of use increases, it is important to monitor adverse effects and co-occurring behaviors to inform timely prevention and harm reduction as needed.

Objective: While polysubstance use is highly prevalent among people who use drugs, the field lacks a reliable assessment that can detect detailed temporal patterns of polysubstance use. This study assessed the test-retest reliability of the newly developed Polysubstance Use–Temporal Patterns Section (PSU-TPS).Methods: Participants who used cocaine plus alcohol and/or marijuana at least once in the past 30 days (n=48) were interviewed at baseline and approximately seven days later (retest) using the Substance Abuse Module (SAM) and the PSU-TPS. Reliability of PSU-TPS measures of quantity, frequency, and duration of polysubstance use was examined using intra-class correlation coefficients (ICCs) and kappa tests. Results: Excellent reliability was observed for frequencies of concurrent polysubstance use patterns in the past 30 days (ICC range: 0.90–0.94) and quantity of alcohol use (ICC=0.83), and fair to good reliability was observed for duration in hours of substance use (ICC range: 0.52–0.73). Conclusion: Detailed information regarding cocaine, alcohol, and marijuana polysubstance use in the past 30 days can be reliably measured with the PSU-TPS. Data on the order and timing of polysubstance use at the hourly level will improve our understanding of the implications of sequential and simultaneous use patterns, which can help inform treatment and prevention efforts.

Objective The majority of prescription drugs, including prescription stimulants, are marketed using multiple brand names, doses, and formulations. There is limited research on the extent to which individuals correctly identify medication by brand name or packaging, but such identification is important for epidemiological studies especially among youth. Testing the ability of youth to identify medications was one aim of the National Monitoring of Prescription Stimulants Study, which focused on the prevalence of prescription stimulant use among youth. Methods Using the entertainment venue intercept method, youth 10 to 18 years of age (n = 11,048) were recruited across 10 metropolitan areas throughout the United States, shown pictures of eight formulations of prescription stimulants, and asked to identify them by name, dosage, and formulation. Results Overall, 27% of youth reported having seen one of the eight stimulant formulations and between 2% and 70% correctly identified name, dose, and formulation. Youths' reports of having seen and correctly identifying medication increased with age except for Daytrana®. Specifically, while 2.8% of youth reported using Adderall® in the past 30 days, only 71.4% correctly identified it. Conclusions These results provide strong evidence of the need for more stringent methods for youth to report drug use.

BACKGROUND: Drugs like ecstasy, cocaine, and counterfeit prescription pills can contain fentanyl. We examined knowledge about potential adulteration/contamination of such drugs among people attending electronic dance music (EDM) parties. METHODS: Adults in New York City were surveyed entering randomly selected EDM parties during the summers of 2018 (n=1,029) and 2019 (n=559). Surveys assessed perceptions that: 1) ecstasy/Molly can contain adulterants more dangerous than MDMA, 2) cocaine can contain fentanyl, and 3) prescription pills from non-pharmacy sources can contain fentanyl. We compared prevalence of perceptions between 2018 and 2019. RESULTS: Prevalence of agreeing that cocaine can contain fentanyl increased from 42.1% to 58.6%, a 39.2% increase (p=.003). Increases in agreement were not significant regarding ecstasy potentially containing adulterants (55.0% vs. 59.0%) and non-pharmacy prescription drugs potentially containing fentanyl (46.8% vs. 52.9%). Those reporting past-year ecstasy use in particular reported increased agreement that ecstasy can be adulterated (from 52.9% to 80.0%, a 51.2% increase; p

Dance festival attendees are at high risk for consuming adulterated drugs. In recent years, drug checking studies have been conducted at various dance festivals to provide valuable harm reduction information to attendees regarding drug content. We conducted a review of the literature to determine the generalizability of findings to the target population of interest-festival attendees at risk for using adulterated drugs. Six published studies involving drug checking at festivals were reviewed. All relied on self-selected samples and male attendees were overrepresented based on previous research. Test methods, drugs tested, definitions of adulteration, and prevalence of adulteration varied across studies. Prevalence of detection of adulterants ranged from 11% to 55%. While the drug checking services described appear to have been beneficial for participants, results have limited generalizability to the target population. We recommend that researchers expand beyond the self-selection model in future studies and utilize recruitment methods that involve random sampling techniques such as systematic random sampling, stratified random sampling, or time-space sampling within festivals. We also recommend that individuals approached are surveyed for demographic characteristics, planned drug use at the festival, and willingness to test their drugs. These methods would help determine how representative the sample is compared to the target population and allow for more generalizable estimates. In conclusion, as these valuable harm reduction services expand, it may be possible to reach a wider portion of the population at risk and to obtain more generalizable estimates of engagement, adulteration, and reactions to learning one possesses adulterated drugs. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Background Novel psychoactive substances (NPS) present continuous and growing challenges for the scientific, medical, and interventional communities as emerging substances on recreational drug markets change national and international drug landscapes. NPS account for an increasing proportion of adverse events, hospitalizations, and deaths due to increasing potency and unanticipated biological effects compared to predecessors. This study evaluated the utility of drug use forums as an early indicator or predictor of impending intoxications with potentially harmful or lethal outcomes prior to their occurrences. Methods Eight NPS were selected for evaluation to assess the relationship between online mentions of drugs and their involvement in toxic exposures or overdoses. Mentions on Reddit drug forum discussions were tallied and toxicology testing results from forensic investigations in the US were assessed. The selected NPS covered several subclasses and a predetermined time range (2013–2020). They included carfentanil, U-47700, eutylone, flualprazolam, N-ethylpentylone, 5F-MDMB-PICA, isotonitazene, and brorphine. Results Seven NPS (excluding 5F-MDMB-PICA) appeared in discussions on Reddit prior to their implication in poisonings or intoxications. Distinct increases and decreases in number of mentions and number of exposures were observed. For most substances (n = 5, 63%), a rise in Reddit mentions was soon followed by a corresponding rise in toxicology positivity. Peak positivity for carfentanil and flualprazolam, however, preceded peak Reddit mentions. Conclusions This study demonstrated the utility of social media sites, such as Reddit, as a predictor for future trends in NPS-related exposures. These results provide confirmation that activity on drug use forums in the virtual world can help predict changes in exposures associated with new or re-emerging NPS in the real world. The results warrant further evaluation as a strategy for inclusion in early warning systems.

Background Despite increasing prevalence of nonmedical ketamine use globally, data on ketamine use disorders, which are classified in the DSM-5 under criteria for phencyclidine, are limited. This study assessed the reliability and applicability of DSM-based diagnostic criteria for ketamine use disorder. Methods Participants who used ecstasy were recruited through the Tri-City Study of Club Drug Use, Abuse, and Dependence in St. Louis, Miami, and Sydney. Those who reported using ketamine (lifetime use >5 times) were included in these analyses (n = 205). Participants were interviewed using the computerized Substance Abuse Module for Club Drugs (CD-SAM) at baseline and 7 days later for the reliability of diagnoses and individual diagnostic criteria. Results Overall, 29.3% met DSM-5 adopted criteria for ketamine use disorder at Time 1. Moderate to excellent test-retest reliability was observed consistently across study sites for any ketamine use disorder (κ = 0.57, Y = 0.61) and severe ketamine use disorder (κ = 0.62, Y = 0.79). Continued use of ketamine despite knowledge of physical or psychological problems was the most frequently endorsed individual criterion (59.0%), followed by reported withdrawal (30.2%) and physically hazardous use (29.8%). All individual criteria had acceptable reliability estimates (κ ≥ 0.41). Conclusions Diagnoses of ketamine use disorder can be reliably evaluated using this fully structured diagnostic instrument's questions and algorithm. Ketamine-related withdrawal among people who use ketamine should be re-evaluated. Considering that after-effects of this dissociative anesthetic can last for many hours, it is important to explore a different timeframe for possible withdrawal effects.