Nicotine and Tobacco Research

Abstract Importance: The overall prevalence of youth nicotine and tobacco product use has declined over recent years, but the product landscape continues to evolve rapidly, particularly with new disposable e-cigarettes and oral nicotine pouches. Objective: To examine changes between 2024 and 2025 in the prevalence of nicotine and tobacco product use among US middle and high school students and describe shifts in product characteristics among current e-cigarette and nicotine pouch users. Design, Setting, and Participants: Repeated cross-sectional study using nationally representative data from the 2024 and 2025 National Youth Tobacco Survey (NYTS), a school-based survey of US students in grades 6-12 (approximately ages 11-18). The analytic sample included 29,678 students in 2024 and 23,557 students in 2025. Exposures: Survey year (2025 vs 2024). Main Outcomes and Measures: Past 30-day use of nicotine/tobacco products, including e-cigarettes, nicotine pouches, cigarettes, and other combustible and non-combustible products. Among current e-cigarette and nicotine pouch users, frequency of use, device type, brands, and flavors were assessed. Results: In 2025, 7.2% (95% CI, 6.4-8.2%) of US middle and high school students reported past 30-day use of any nicotine/tobacco product, compared with 8.1% (7.4-8.9%) in 2024. E-cigarettes remained the most commonly used product (5.2%, 4.5-5.9%); 1.7% (1.4-2.1%) used nicotine pouches, 1.7% (1.4-1.9%) smoked cigarettes, and 2.7% (2.4-3.1%) smoked any combustible tobacco product. Among current e-cigarette users, 40.7% (36.7-44.9%) reported frequent use and 27.0% (24.0-30.2%) reported daily use in 2025. Disposable e-cigarette use increased from 55.8% (52.6-59.0%) in 2024 to 66.7% (62.5-70.7%) in 2025, while pod/cartridge device use declined. Flavored product use was reported by 90.0% of e-cigarette users and 88.0% of nicotine pouch users. The most commonly reported brands were Geek Bar among e-cigarette users (61.1%) and ZYN among nicotine pouch users (69.4%). Conclusions and Relevance: Overall youth nicotine and tobacco use remains relatively low, but the product landscape is evolving rapidly, with increasing disposable device use and shifting brand preferences. These findings highlight the importance of ongoing, product-specific surveillance to inform public health strategies and regulatory policies.

BackgroundDespite their potential to serve as a reduced-harm alternative to combustible tobacco, e-cigarette take-up remains low among older (45+) adult smokers, especially in the U.S. While social media is a known driver of vaping attitudes and behaviors in younger populations, its influence on older smokers is poorly understood. This paper provides the first focused analysis of e-cigarette-related social media exposure in this population, documenting its prevalence, characteristics, and attitudinal correlates. MethodsData come from an opt-in survey of U.S. adults (N = 974) recruited via Prolific, comprising three groups: (i) non-vaping smokers aged 45+ (N = 484), (ii) former-smoking vapers aged 45+ (N = 149), and (iii) any-vaping-status smokers aged 18-35 (N = 341). Descriptive statistics, weighted to U.S. population benchmarks, characterize self-reported exposure to e-cigarette-related content on social media. Logistic regressions estimate associations between exposure and intentions for future e-cigarette use, e-cigarette harm perceptions, and related attitudes. ResultsOlder smokers (35.3%) reported exposure to e-cigarette-related content on social media less frequently than both older vapers (44.0%) and younger smokers (72.0%). For older smokers, e-cigarette health risks were the most frequently reported topic of content viewed, followed by youth vaping and e-cigarette addiction. Among this group, exposure was positively associated with stated intentions for future e-cigarette use. Exposure was not significantly associated with perceived e-cigarette harms for any group. ConclusionsFindings provide suggestive evidence that social media exposure may promote e-cigarette adoption among older smokers. However, the cross-sectional design limits causal inference, and the observed associations may reflect selection bias or reverse causality. If a causal relationship exists, the patterns observed suggest that exposure influences e-cigarette adoption through mechanisms other than updating beliefs about e-cigarette risks. While these results tentatively support the potential of social media as a channel for older-smoker harm reduction, any policy applications must carefully weigh privacy concerns and risks to youth. Rigorous experimental studies are needed to confirm these findings and clarify how social media might be leveraged to improve public health outcomes among older smokers.

Background The clinical safety profile of e-cigarette use for smoking reduction remains poorly characterized. This study compared the relative safety and tolerability of nicotine e-cigarette use with non-nicotine e-cigarettes or a non-aerosol cigarette substitute (CS) among adults interested in reducing their smoking. Methods We conducted a secondary analysis of adverse events (AEs) reported in a 6-month, double-blind RCT involving 520 participants assigned to either e-cigarettes with 0, 8, or 36 mg/mL nicotine or a CS. AEs were coded using CTCAE V4.0 and assessed for frequency, severity, seriousness and relatedness across groups. Cumulative incidence was calculated over 24 weeks. We estimated risk differences (RDs) and 95% confidence intervals (CIs) for frequently reported AEs (>=1% of participants overall) comparing e-cigarette vs. CS and nicotine versus non-nicotine e-cigarette groups. Fisher's exact test, with adjustment for multiple comparisons, was used to assess statistical significance. Results Most study-related AEs (those rated as possibly, probably, or definitely related by medical monitor) were mild in severity and none were classified as serious. At 24 weeks, cumulative incidence of first study-related AE was highest in the 36 mg/mL (37.0%) and 8 mg/mL (35.2%) e-cigarette groups, followed by 0 mg/mL (23.4%), and lowest in CS group (2.5%). E-cigarette users experienced significantly greater risks of cough (RD [95%CI]: 8.5% [5.6-11.3]), headache (RD [95%CI]: 5.4% [3.3-7.6]) and sore throat (RD [95%CI]: 5.4% [3.2-7.6]) as compared with the CS group. Cough was also more common in those randomized to nicotine versus non-nicotine e-cigarettes (RD [95%CI]: 8.1% [3.4-12.8]). Conclusion All study products were generally well-tolerated; however, AEs were more common in e-cigarette groups, especially with nicotine. Findings highlight the need to monitor common symptoms such as cough, headache, and sore throat in clinical and regulatory evaluations of e-cigarette safety.

Importance: Understanding patterns of substance use and environmental exposures to tobacco, cannabis, and electronic nicotine delivery systems (ENDS) among youth is critical for developing targeted prevention strategies, particularly as co-use of tobacco, ENDS, and cannabis becomes more prevalent. Objective: To identify latent classes of tobacco, ENDS, and cannabis use, and environmental exposures to these products among adolescents and emerging adults. Design, Setting, and Participants: Data from the Environmental influences on Child Health Outcomes (ECHO) consortium (3rd data release, 2018 to 2022) were analyzed from March 2025 to January 2026. The sample (N=2,786) included early adolescents (ages 11 to 13; n=226, 7.9%), middle adolescents (ages 14 to 17; n=1,248, 43.4%), and late adolescents/emerging adults (ages 18 to 24; n=1,402, 48.7%) from 19 ECHO cohorts. Main Outcomes and Measures: The Youth Risk Behavior Survey, Substance Use module measured experimental and current use of cannabis, ENDS, and tobacco products, as well as daily environmental exposure to tobacco smoke, nicotine aerosols, and cannabis smoke within home and social contexts. A multiple group latent class analysis was used to identify distinct latent classes of substance use and environmental exposure to tobacco smoke, nicotine aerosols, and cannabis smoke and compared class prevalences across early, middle, and late adolescence. Results: Four latent classes were identified, including: No Use/No Exposure (53%), No Use, Polyexposure (10%), Experimental Use/Low Exposure (22%), and Polysubstance Use/High Polyexposure (14%). Cannabis was the most used substance (34% experimental or current use) and the most common source of environmental exposure (20%), followed by ENDS use (26% experimental or current use; 19% environmental exposure) and combustible tobacco (15% use; 19% environmental exposure). The No Use/No Exposure and No Use/Polyexposure classes were primarily made up of early and middle-aged adolescents, whereas the Experimental Use/Low Exposure and Polysubstance Use/High Polyexposure classes primarily consisted of late adolescents and emerging adults. Conclusions: Our study revealed distinct, developmentally patterned groupings of substance use and environmental exposure among US adolescents and emerging adults, highlighting the need for developmentally tailored interventions, messaging, and policies that address both active use and environmental exposure across adolescence.

"Dry Hitting" is a unique phenomenon of e-cigarette use that has been shown to produce toxic chemical degradants and byproducts. Although it is widely understood that nicotine exposure during adolescence impacts neurobiological and behavioral function, little is known about how dry hitting may impact users. We hypothesized that subjects repeatedly exposed to nicotine dry hit vapor would exhibit distinct behavioral responses compared with saturated nicotine vapor and would differentially alter the expression of perineuronal nets (PNNs) in the rodent brain. Using a customized system of e-cigarette vapor inhalation, adolescent male Wistar rats (PND 31-40) received vaporized nicotine (30 or 60 mg/mL; [~]2.5-3 mL/cage), nicotine with dry hits (60 mg/mL; 1.75-2 mL/cage), or propylene glycol (PG) vehicle for 30 minutes over 7 daily sessions. Locomotor activity, antinociception, and elevated plus maze testing were used to assess behavioral response to drug intoxication and tolerance. Immunohistochemistry was used to identify Wisteria Floribunda Agglutinin (WFA)-positive PNN structures in the amygdala and insular cortex. Rats exposed to dry hits exhibited behavioral responses (locomotor sensitization, antinociception) similar to those of rats exposed to saturated nicotine vapor, but spent more time in the open arms of the elevated plus maze. Immunohistochemical analyses confirmed significantly greater WFA intensity in the central nucleus of the amygdala, but not the basolateral amygdala or insular cortex, of rats exposed to dry hits. Overall, these data confirm the impact of dry hit vapor on behavioral responses and perineuronal net expression in rats during adolescence.

IntroductionAlthough prior studies suggest e-cigarette use is associated with worse mental health, it remains unclear whether these associations persist independent of diagnosed depression and how tobacco use and depression jointly affect health-related quality of life. Although the long-term health risks of vaping are still unknown, self-reported health is a reliable measure of quality of life. This study provides the first health utility estimates of the independent and combined effects of cigarette use, e-cigarette use, and depression on health-related quality of life. MethodsWe analyzed 2022-2023 Behavioral Risk Factor Surveillance System data on health-related quality of life as measured by self-reported physically or mentally unhealthy days in the past 30 days. The average number of unhealthy days was estimated by age, gender, smoking status (current versus non-smoking), depression status (received a prior diagnosis), and current e-cigarette use status (every day or some day use). We converted the number of overall healthy days into EQ-5D utility scores by age-specific percentile matching of BRFSS and MEPS distributions, a method developed by Jia and Lubetkin. ResultsCigarette use, e-cigarette use, and depression were each associated with worse health-related quality of life. Mentally unhealthy days increased with the accumulation of these conditions. Associations with physically unhealthy days followed a similar pattern, particularly among younger adults, although the magnitude of association was smaller. E-cigarette use alone was associated with 2.0-4.2 (95% CI: 2.0-4.6) additional mentally unhealthy days per month across all age groups. Notably, e-cigarette use was independently associated with poorer mental health among adults aged 18-64 with or without diagnosed depression. After accounting for smoking and depression status, e-cigarette use was associated with disutility scores of 0.011 in men and 0.015 in women among young adults, with the largest losses observed when multiple conditions co-occurred. ConclusionE-cigarette use is associated with poorer health-related quality of life, particularly among younger adults, and these effects are amplified when combined with cigarette use and depression. Quantifying these joint impacts as health utility losses highlights the importance of addressing e-cigarette use within integrated tobacco control and mental health policies, especially for young populations.

Tobacco use disorder is a chronic condition characterized by compulsive nicotine use, withdrawal, and relapse following abstinence. Impulsivity contributes to persistent nicotine use and poor cessation outcomes. This study examined whether nicotinic acetylcholine receptor (nAChR) modulators alter impulsive action in a nicotine self-administration Go/No-Go task in male and female rats. Rats acquired intravenous nicotine self-administration and were then trained in a Go/No-Go procedure in which active lever presses were reinforced during Go periods but not during No-Go periods. We then assessed the effects of varenicline (0.1-3 mg/kg), nicotine (0.1-0.6 mg/kg), and the nAChR antagonist mecamylamine (0.5-2 mg/kg) in the Go/No-Go procedure. Varenicline and nicotine pretreatment reduced active responding during both Go and No-Go periods, whereas mecamylamine selectively reduced responding during No-Go periods. Mecamylamine decreased the percentage of active responses during No-Go trials, indicating reduced bias toward the nicotine-associated lever. In contrast, nicotine and varenicline did not alter response allocation, suggesting that their effects reflected nonspecific reductions in responding rather than changes in impulsive action. No sex differences were observed. Substituting saline for nicotine during self-administration did not alter active responding during Go periods, but rats in the saline group had fewer active responses during No-Go periods than rats in the nicotine group. These results show that chronic nicotine self-administration increases impulsive action and that nAChR antagonism, but not agonism or partial agonism, reduces nicotine-related impulsive action. This work supports the utility of the Go/No-Go self-administration task for investigating nAChR-dependent mechanisms underlying nicotine-induced impulsivity.

ABSTRACT Background and aims: Mental and behavioral disorders due to use of tobacco (MBDT) present a critical challenge to global health, yet modifiable lifestyle factors for reducing its risk remain poorly understood. Given that dietary fibre can affect mental health through gut-brain communication, we sought to explore how fibre intake relates to MBDT risks in smokers. Methods: We specifically evaluated the link between dietary fibre intake and MBDT within a smoking population. Utilizing the UK Biobank (UKB) database, we performed cross-sectional (N=19,943) and prospective cohort (N=19,885) evaluations applying logistic and Cox proportional hazards models, respectively. To determine potential causality, two-sample Mendelian randomization (MR) was applied, relying on GWAS summary data derived from the IEU Open GWAS Project and FinnGen repositories. Results: Cross-sectional findings indicated that individuals in the top quartile (Q4) of fibre intake exhibited decreased MBDT risks relative to the bottom quartile (Q1) (OR: 0.32, 95% CI: 0.13-0.79). Over a median observation time of 12.84 years, the prospective evaluation demonstrated a notable inverse correlation (Q4 HR: 0.46, 95% CI: 0.40-0.54). Non-linear modeling via restricted cubic splines uncovered an L-shaped dose-response curve. Furthermore, MR results confirmed a genetically predicted protective causality (IVW OR: 0.68, 95% CI: 0.49-0.95), which remained consistent across sensitivity validations. Conclusions: Among smokers, higher dietary fibre intake is robustly associated with a reduced risk of mental and behavioral disorders due to the use of tobacco, offering a modifiable dietary target for public health interventions.

Introduction: Monitoring trends in transitions in the use of electronic nicotine delivery systems (ENDS) and cigarettes among youth is important for understanding the potential public health impacts of these products. Methods: Using a weighted Markov multistate transition model accounting for complex survey design, we estimated transition rates and one-year transition probabilities between never, non-current, ENDS-only, and cigarette use (with or without dual use of ENDS) among 26,744 youth aged 12-17 years who participated in at least two consecutive waves from Waves 2-7.5 (approximately 2015-2023) of the nationally representative Population Assessment of Tobacco and Health (PATH) Study. We also estimated transitions stratified by ages 12-14 and 15-17 years. Results. The one-year probability of ENDS-only initiation from never use among youth peaked in 2017-19 (Waves 4-5) at 4.0% (95%CI: 3.6-4.3%) and was higher for 15-17-year-olds at 5.8% (95%CI: 5.2-6.4%) than 12-14-year-olds at 2.2% (95%CI: 1.8-2.6%). In the following years, ENDS-only initiation rates declined and plateaued, with 2.6% (95%CI: 2.3-3.0%) initiation in 2022-23. Cigarette initiation from never use decreased over 2015-23 from 0.8% (95%CI: 0.6-1.0%) in 2015-16 to 0.1% (95%CI: 0.0-0.2%) in 2022-23. There was an increase in the fraction of youth who transitioned from non-current product use to ENDS-only use from 13.7% (95%CI: 7.5-20.0%) in 2015-16 to 35.1% (95%CI: 25.4-44.8%) in 2022-23, paired with a decrease in non-current use to cigarette use from 20.9% (95%CI: 11.8-30.0%) to 6.3% (95%CI: 1.7-10.8%). Transitions from ENDS-only or cigarette use to non-current use remained relatively constant over time at around 25% and 15% per year, respectively. Conclusion. ENDS-only use initiation has changed over time, peaking around 2019 and subsequently decreasing and plateauing, but cessation rates for both ENDS and cigarettes have remained relatively stable. Thus, interruption of tobacco product initiation may be the most effective approach to reducing tobacco product use among youth.

ObjectiveNicotinic acetylcholinergic receptors (nAChRs), comprising of and {beta} subunits are present in the brain and whole body. The less abundant 2-subunit is a fast-acting receptor subtype and plays an important role in cognition and learning. To understand cellular functional consequences, this study evaluated glucose metabolism using [18F]FDG PET/CT in 2 knockout (2KO) and 2 hypersensitive (2HS) mice. MethodsControl (CN; 4M, 4F), 2 knockout (2KO; 4M, 4F) and 2 hypersensitive (2HS; 4M,4F), 12-16 month old mice were used. Mice were fasted and injected with [18F]FDG (3-5 MBq) while awake. After 40 minutes they underwent whole body PET/CT. On a separate day, nicotine challenge [18F]FDG studies were done. Reconstructed images were analyzed to obtain standard uptake values (SUV) of [18F]FDG in brain and interscapular brown adipose tissue (IBAT). Statistical analysis was performed. ResultsThe 2HS male mice exhibited the largest brain increase in [18F]FDG compared to 2KO male mice. The rank order of brain [18F]FDG uptake in the 3 groups: 2HS[male]> CN[male]> 2KO[male]> CN[female]= 2KO[female][≥] 2HS[female]. Nicotine treatment reduced brain [18F]FDG uptake in all mice. Females had lower [18F]FDG uptake compared to males and were less sensitive to 2 nAChR. In the case of IBAT, 2KO mice had significantly higher baseline [18F]FDG uptake compared to the other two groups: 2KO[male]> 2KO[female]> 2HS[female]> 2HS[male]> CN[female]> CN[male]. Nicotine decreased IBAT in 2KO mice rather than increase as observed in CN and 2HS mice. Conclusions2 nAChRs plays a significant role in brain activation as exhibited by the increase in [18F]FDG in 2HS mice. In the absence of regulatory control by the 2 nAChR, the 2KO mice IBAT exhibited higher [18F]FDG IBAT compared to controls and 2HS mice. Female mice were less affected by nicotine compared to the male mice. Overall, 2 nAChRs played a significant role in glucose metabolism in the brain and IBAT.

ObjectivesUptake of evidence-based smoking cessation support remains limited. Digital interventions offer the prospect of scalable and highly accessible support. Smoke Free, a digital mobile application using established behaviour change techniques, has shown promise, but no large-scale randomised controlled efficacy trial has yet been conducted. We assessed its effectiveness for smoking cessation. DesignIn this prospective, randomised, controlled, two-arm, parallel clinical trial with 6-month follow-up, study personnel and patients were blinded. SettingThe trial was conducted nationwide in Germany, utilising a decentralised, fully remote trial design. Enrolment took place digitally after receiving brief advice from a healthcare professional, following guidelines for primary care. ParticipantsOut of a volunteer sample of 1850 patients assessed for eligibility, 1466 adult cigarette smokers who had at least moderate cigarette dependence (F17.2, FTCD[&ge;]3) were recruited between August 2023 and February 2024; 84.1% (1233 participants) completed the primary outcome measure. InterventionsThe intervention group (IG) received the Smoke Free app including behaviour-change missions and gamification elements, while the control group (CG) received a text-only cessation information app. Both groups received brief advice from a healthcare professional. Main outcome measuresThe prespecified primary outcome was self-reported 7-day point-prevalence abstinence from combustible tobacco at 6 months post-randomisation; secondary outcomes included biochemical validation of abstinence in participants providing a saliva sample (59% of eligible participants). ResultsSelf-reported abstinence (primary outcome) was significantly higher in the IG compared with the CG (283 [39.3%] vs. 182 [24.4%], OR=2.01, 95% CI 1.60 to 2.50, p<0.0001). The NNT was 6.7 (5.1 to 9.8). The effect was consistent with biochemical validation (OR=1.76, 95% CI 1.27 to 2.44, p<0.0001) and across secondary outcomes and sensitivity analyses. The 6-month follow-up rates for the primary outcome did not differ between groups (IG: 601 [83.5%]; CG: 632 [84.7%]; p=0.52). Eighty-four serious adverse events were reported by 75 participants (IG: 31, 4.3%; CG: 44, 5.9%; p=0.53); none were treatment-related. ConclusionsThe Smoke Free app is effective for aiding smoking cessation in at least moderately dependent cigarette smokers compared with an informational app when provided as an adjunct to brief advice from a healthcare professional. Trial registrationThe trial was registered with the German Clinical Trials Register (DRKS00031140). FundingSmoke Free 23 GmbH (for-profit company).

BackgroundSubstance use initiation in adolescence is influenced by both genetic and environmental factors; however, large-scale genetic studies often treat initiation as a binary outcome and underuse longitudinal timing information. MethodsWe conducted time-to-event (survival) genome-wide association analyses (GWAS) of initiation for four outcomes--alcohol, nicotine, cannabis, and any substance use--using longitudinal follow-up data from the Adolescent Brain Cognitive Development (ABCD) Study. We performed ancestry-stratified GWAS within European (EUR), African (AFR), and Hispanic (HISP) groups, applying consistent quality control and covariate adjustment. Summary statistics were harmonized across ancestries and meta-analyzed using inverse-variance weighted fixed-effects and DerSimonian-Laird random-effects models. We evaluated genomic inflation and heterogeneity (Cochrans Q and I2), identified independent lead variants at genome-wide and suggestive significance thresholds, and assessed cross-trait overlap of associated loci. ResultsIn the multi-ancestry meta-analysis, we observed suggestive association signals across traits (minimum p-values: alcohol [~] 1 x 10-7, any [~] 1 x 10-7, cannabis [~] 5 x 10-8, nicotine [~] 1 x 10-8). Nicotine initiation showed one genome-wide significant variant in both fixed- and random-effects meta-analyses (p < 5 x 10-8). Across traits, suggestive loci demonstrated limited overlap, with the strongest concordance between alcohol and any substance use, consistent with shared liability. Heterogeneity statistics indicated that some loci exhibited cross-ancestry variation in effect estimates. ConclusionsSurvival GWAS leveraging initiation timing can identify genetic signals that may be missed by binary designs and enables principled multi-ancestry synthesis. Our results highlight both shared and trait-specific genetic contributions to early substance initiation and provide a foundation for downstream functional annotation and integrative modeling with environmental risk factors. These findings demonstrate the value of incorporating developmental timing into genetic discovery and provide a framework for integrating longitudinal risk modeling with genomic analyses.

Nicotine use disorder shows heterogeneity in treatment response, potentially reflecting differences in underlying neural circuitry, particularly in the presence of depression. We examined real-time neural dynamics during nicotine inhalation in two chronic users - one with depression and one without - using simultaneous hippocampal recordings from responsive neurostimulation (RNS) electrodes and scalp EEG. Oscillatory activity and hippocampal-cortical connectivity were analyzed in relation to mood and craving. Oscillatory activity tracked mood in the non-depressed individual but was attenuated or reversed in the depressed individual, suggesting reduced reward-related neural responsiveness. In contrast, both participants showed reduced alpha hippocampal-cortical connectivity following nicotine use, suggesting a shift from reward-seeking to reward and relief processing. These findings support a network-based framework of nicotine-driven neural dynamics and provide preliminary evidence that depressive status may modulate these processes. Although limited to two cases, this work highlights the potential for identifying neurophysiological subtypes of nicotine users and informs future efforts toward personalized treatment approaches.

Nearly one third of women of reproductive age in the United States are prescribed opioids annually; 14% of women fill an opioid prescription during pregnancy, and one in five report misuse. Opioid use during pregnancy has given rise to an increasing population of infants born with gestational opioid exposure. Although substantial clinical work has focused on treating these infants as they experience opioid withdrawal symptoms at the time of birth, notably few studies have examined the effects of gestational opioid exposure on brain development and long-term cognitive function. During typical brain development, endogenous opioids and their receptors are highly expressed by neural progenitor cells, neurons, and glia where they modulate cell proliferation, differentiation, and maturation. Thus, any disruption to the endogenous opioid system during the critical period of brain development may have lasting consequences on brain cell populations and the behaviors they influence. Indeed, opioid-exposed infants have smaller brains than age-matched peers and show significant neurodevelopmental impairment; they also have higher rates of learning disability at school age. To investigate how exposure to exogenous opioids during brain development affects neural maturation in the hippocampus, a brain region critical for learning and memory, our lab has developed a clinically relevant perigestational morphine exposure rat model. The current study reports that perigestational exposure to morphine delays postnatal hippocampal neuronal maturation, alters astrocyte and oligodendrocyte proliferation, and alters expression of brain-derived neurotrophic factor (BDNF), a protein crucial for healthy brain growth. Furthermore, we show that environmental enrichment rescues BDNF deficits, offering evidence for the effectiveness of non-invasive, non-pharmacological intervention for developmental consequences of perigestational opioid exposure.

Background and aimsPerseverative behaviours are commonly assessed using operant paradigms in which rodents work for drugs or food under physiological deprivation, limiting translational relevance to some behavioural addictions. Here we validated an operant paradigm in which the acquired behaviour is driven neither by physiological needs nor hedonic responses. MethodsMice were trained to lever-press for green light. Exp.1 used a within-subjects design to examine lever discrimination and whether responding could be "satiated" by light preexposure. Exp.2 examined instrumental contingency using a between-subjects design, with light delivery equated between contingent and non-contingent groups. Exp.3 replaced green light with dim red light producing less retinal photoreceptor excitation but comparable heat to assess non-photic cues. Exp.4 examined whether green light could affect food seeking different motivational states. ResultsIn Exp.1, green light supported lever discrimination. Among high responders, the satiation effect was modest (<15% reduction) and did not deter lever pressing. In Exp.2, instrumental contingency promoted response acquisition whereas random light delivery did not. In Exp.3, dim red light failed to sustain behaviour, producing [~]50% response decrement. In Exp.4, light potentiated food seeking under ad libitum feeding. Discussion and conclusionsResponse-contingent light serves as a reward to establish operant responding, which cannot be explained by alerting effects or thermal cues. Our study bridges the gap between animal models and findings from humans that coloured light may exacerbate smartphone use and that light therapy may reshape reward circuits in individuals with Internet gaming disorder symptoms [Li et al. (2026) Advanced Science 13:e14044].

BackgroundLoss of control over drinking is a hallmark feature of alcohol use disorder (AUD) that is modeled preclinically through escalation of ethanol consumption and aversion-resistant drinking. Prior work with other reinforcers suggests that within-session unpredictable, intermittent access (uIntA) promotes loss of control over intake. However, the effect of uIntA on voluntary ethanol consumption is unknown. MethodsMale and female Long-Evans rats (n=9-10/group) underwent seven weeks of daily voluntary ethanol (20% v/v) drinking sessions under either a continuous access (ContA) or uIntA schedule. Following four weeks of baseline, rats were rendered dependent using a two-week chronic intermittent ethanol vapor exposure procedure. Daily testing was maintained through one week into withdrawal from vapor exposure. On the final day of testing, ethanol was adulterated with quinine (30 mg/L) to assess aversion-resistant drinking. ResultsRats drinking under ContA and uIntA exhibited similar levels of average daily ethanol consumption at baseline. However, uIntA elicited a more robust dependence-induced escalation of ethanol consumption compared to ContA, with uIntA sustaining escalation through early protracted withdrawal. Additionally, while rats with ContA to ethanol remained sensitive to quinine even after chronic ethanol vapor exposure, uIntA promoted aversion-resistant drinking in ethanol dependent rats. ConclusionsThese results demonstrate that, compared to ContA, uIntA maintains ethanol drinking and exacerbates AUD-related symptomatology while also providing researchers with the ability to capture additional measures of motivation and drinking patterns without increasing experimental burden. This work positions uIntA as a powerful tool to assess psychological and neurobiological factors underlying loss of control over drinking.

Cannabis (marijuana) is the most widely used recreational drug in the USA accounting for about 62 million users in 2024. Among cannabis users, 26% are of prime reproductive age (18-25 years). Delta-9 tetrahydrocannabinol (THC) is the principal psychoactive component of cannabis and has been detected in human seminal fluids. Although abundant evidence indicates adverse effects of THC exposure on spermatogenesis in different species, acute effects of THC on postejaculatory sperm including fertilization potential and subsequent carryover effects on embryo development are largely unknown. The present study was designed to provide missing information on structural and mechanistic effects of THC exposure to postejaculatory sperm function by evaluating sperm indices often overlooked or masked during clinical evaluation. A bovine embryo continuum model was employed to determine effects of THC on sperm structure, kinematics, bioenergetics, and binding mechanisms. Effects of THC on the sperm genomic and epigenomic landscape were determined, complemented by paternal carry over effects on embryo development as a human translational model to elucidate paternal effects on future development, and to mirror sperm exposure during transport within the female reproductive tract. Cryopreserved bovine sperm from three bulls were independently exposed to physiologically relevant concentrations of THC (0 and 32nM, n = 2 individual replicates/bull) for 24 h under non-capacitating conditions at 25{degrees}C followed by quantification of sperm kinematics at 37{degrees}C. Samples of THC-exposed sperm and vehicle-control (0.1% DMSO) were collected in replicate following immediate addition of THC (0 h) and again at 24 h. DNA damage, acrosome integrity, bioenergetics, changes to DNA methylation and embryo development were quantified. Data were analyzed by logistic regression with a generalized linear mixed effect model. Computer-assisted sperm assessment revealed a reduction in progressive motility of THC-exposed sperm after 24 h while other parameters were not affected. Acrosome integrity as determined by flowcytometric analysis with FITC-PSA was severely compromised in THC-exposed sperm (P [&le;] 0.05), despite no detectable difference in capacitation status using merocyanine staining. Similarly, DNA integrity as determined by TUNEL assay was significantly impaired after 24 h of THC exposure (P [&le;] 0.05). Mechanistic effects of THC were explored through characterization of the transmembrane G-protein coupled cannabinoid 1 receptor (CB1). CB1 is expressed in the post-acrosomal region and its abundance decreased as compared to unexposed sperm. Alterations to the methylation landscape of sperm were then determined after 24 h of THC exposure through whole-genome Enzymatic Methyl Sequencing. PCA analysis indicated that sperm from different males formed distinct clusters, implying individual differences among bulls, while the effects of THC exposure produced tighter clusters. Paternal carryover effects on embryos derived by in vitro fertilization from THC exposed sperm had reduced 2-cell cleavage, 8-16 cell morula development, and reduced blastocyst development compared to unexposed sperm (46% vs. 33%). In conclusion, post-ejaculatory mammalian sperm exposure to THC compromises acrosome integrity, induces DNA damage, changes the sperm methylome, and reduces developmental potential. Collectively, these data implicate new considerations for recreational and clinical use of cannabis that impact cellular and molecular mechanisms important for sperm function with detrimental consequences for gamete interaction and embryo development.

AimWe examined associations between smoking and HbA1c among U.S. adults, and whether these associations vary by diabetes status. MethodsWe analyzed NHANES data from 2015-2018 for adults aged [&ge;]20 years. Smoking was assessed by self-report and serum cotinine. Survey-weighted multivariable linear regression was used to evaluate the association between smoking and HbA1c in the full population (N=9,214) and in adults without diabetes (N=7,328), adjusting for demographics, blood pressure, waist circumference, lipids, and C-reactive protein. ResultsAfter adjustment for cardiometabolic covariates, there was no significant association between smoking and HbA1c in the full population (former: {beta}=0.029%, p=0.30; current: {beta}=0.053%, p=0.13). Among adults without diabetes, former smoking was not associated with HbA1c, whereas current smoking remained significantly associated (former: {beta}=-0.001%, p=0.923; current: {beta}=0.067%, p<0.001). These findings were similar when cotinine was used as the exposure measure, with active smoking ([&ge;]3.0 ng/mL) associated with higher HbA1c among non-diabetic adults (p<0.001), but not in the full population. ConclusionsAmong adults without diabetes, current but not former smoking was associated with higher HbA1c. The absence of an association in former smokers suggests that this effect may attenuate following cessation. These findings support early cessation interventions and may inform cessation counseling and diabetes screening.

Synthetic cathinones, colloquially called bath salts or flakka, are a group of psychoactive substances used recreationally, including mephedrone and eutylone. Studies examining the prevalence of bath salt use among select samples in the United States have found that approximately 1% of nightclub attendees in New York, high school seniors, and college students have used them. The purpose of this study was to examine the national prevalence of lifetime and past-12-month use of bath salts among a nationally representative sample of persons in the United States from 2021 to 2023. This study also examined nationwide poison center data to identify the number of poisonings from 2021 to 2023 in which bath salt use was intentional and not necessarily an adulterant in another illicitly obtained recreational substance. This study identified the prevalence of lifetime bath salt use among a nationally representative sample of persons 12 years and older in the U.S. to be 0.2% (n = 670,611) in 2021, 0.3% (n = 838,941) in 2022, and 0.3% (n = 836,128) in 2023. The national prevalence of past-12-month bath salt use was 0.0% (n = 111,039) in 2021, 0.1% (n = 167,815) in 2022, and 0.1% (n = 152,276) in 2023. From 2021 to 2023, there were 148 cases in which bath salt use was intentional and involved in a reported poisoning to one of the 55 poison centers in the U.S. Future studies are needed to examine risk factors associated with bath salt-related poisonings.

Relapse to opioid use during abstinence is often triggered by drug-associated cues but the persistence of this effect across the lifespan is unknown. Using a rat model, we found that relapse provoked by heroin-predictive discriminative stimuli persisted for over one year of abstinence, suggesting enduring, potentially lifelong opioid relapse vulnerability.