Prenatal exposures to tobacco and cannabis: Associations with adult electronic cigarette use

Prenatal Δ9-Tetrahydrocannabinol Exposure in Males Leads to Motivational Disturbances Related to Striatal Epigenetic Dysregulation

BACKGROUND

Cannabis remains one of the most widely abused drugs during pregnancy. In utero exposure to its principal psychoactive component, Δ⁹-tetrahydrocannabinol (THC), can result in long-term neuropsychiatric risk for the progeny. This study investigated epigenetic signatures underlying these enduring consequences.

METHODS

Rat dams were exposed daily to THC (0.15 mg/kg) during pregnancy, and adult male offspring were examined for reward and depressive-like behavioral endophenotypes. Using unbiased sequencing approaches, we explored transcriptional and epigenetic profiles in the nucleus accumbens (NAc), a brain area central to reward and emotional processing. An in vitro CRISPR (clustered regularly interspaced short palindromic repeats) activation model coupled with RNA sequencing was also applied to study specific consequences of epigenetic dysregulation, and altered molecular signatures were compared with human major depressive disorder transcriptome datasets.

RESULTS

Prenatal THC exposure induced increased motivation for food, heightened learned helplessness and anhedonia, and altered stress sensitivity. We identified a robust increase specific to males in the expression of Kmt2a (histone-lysine N-methyltransferase 2A) that targets H3K4 (lysine 4 on histone H3) in cellular chromatin. Normalizing Kmt2a in the NAc rescued the motivational phenotype of prenatally THC-exposed animals. Comparison of RNA- and H3K4me3-sequencing datasets from the NAc of rat offspring with the in vitro model of Kmt2a upregulation revealed overlapping, significant disturbances in pathways that mediate synaptic plasticity. Similar transcriptional alterations were detected in human major depressive disorder.

CONCLUSIONS

These studies provide direct evidence for the persistent effects of prenatal cannabis exposure on transcriptional and epigenetic deviations in the NAc via Kmt2a dysregulation and associated psychiatric vulnerability.

In-utero cannabis exposure and long-term psychiatric and neurodevelopmental outcomes: The limitations of existing literature and recommendations for future research

Given increases in cannabis use in pregnancy and animal model research showing effects of in-utero cannabis exposure, high-quality information on long-term consequences of in-utero cannabis exposure in humans is needed. While reviews have summarized findings from observational studies with humans, reviews have not focused on limitations of these studies and recommendations for future research. Therefore, we critically reviewed observational research on in-utero cannabis exposure and psychiatric and neurodevelopmental outcomes measured at or after age 3 and provided recommendations for future research. We used Web of Science, Google Scholar, and work cited from relevant identified publications to identify 46 papers to include in our review. Our review includes two main sections. The first section highlights the extensive limitations of the existing research, which include small and nongeneralizable samples, reliance on self-reported data, lack of detail on timing and amount of exposure, inclusion of older exposure data only, not accounting for important confounders, inclusion of potential mediators as covariates, not including outcome severity measures, and not assessing for offspring sex differences. The second section provides recommendations for future research regarding exposure and outcome measures, sample selection, confounder adjustment, and other methodological considerations. For example, with regard to exposure definition, we recommend that studies quantify the amount of cannabis exposure, evaluate the influence of timing of exposure, and incorporate biological measures (e.g., urine toxicology measures). Given that high-quality information on long-term consequences of in-utero cannabis exposure in humans does not yet exit, it is crucial for future research to address the limitations we have identified.

Maternal trajectories of cannabis use and young adult cannabis and nicotine dependence

INTRODUCTION

The goals of this study were to model maternal patterns of cannabis use from one year pre-pregnancy to 16 years postpartum and to determine if different patterns of maternal cannabis use predicted offspring substance use at age 22.

METHODS

Women were recruited from a prenatal clinic between 1982 and 1984. Maternal cannabis use was assessed by trained interviewers twice during pregnancy, at delivery, 8 and 18 months, 3, 6, 10, 14, and 16 years postpartum. At age 22, substance use and dependence were measured in offspring. Growth mixture models of maternal cannabis use were calculated and adult offspring substance use outcomes were regressed onto maternal cannabis trajectory classes (n = 551).

RESULTS

There were five distinct patterns of maternal cannabis use. Offspring of mothers who were chronic cannabis users were more likely to use cannabis (p < 0.001) and develop CUD (p < 0.05) than offspring whose mothers did not use cannabis. Offspring of chronic cannabis users were also more likely to be nicotine dependent by age 22 than offspring whose mothers did not use cannabis (p < 0.01) and than offspring whose mothers were decreasingly likely to use over time (p < 0.01).

CONCLUSIONS

Integrated variable- and person-centered analyses revealed long-term and meaningful patterns of cannabis use and desistance. Chronic maternal cannabis use is a risk factor for regular and dependent cannabis use and for dependent tobacco use among young adult offspring. These findings have implications for maternal-child health given the increasing prevalence of cannabis use among women.

Lower-Risk Cannabis Use Guidelines (LRCUG) for reducing health harms from non-medical cannabis use: A comprehensive evidence and recommendations update

BACKGROUND

Cannabis use is common, especially among young people, and is associated with risks for various health harms. Some jurisdictions have recently moved to legalization/regulation pursuing public health goals. Evidence-based 'Lower Risk Cannabis Use Guidelines' (LRCUG) and recommendations were previously developed to reduce modifiable risk factors of cannabis-related adverse health outcomes; related evidence has evolved substantially since. We aimed to review new scientific evidence and to develop comprehensively up-to-date LRCUG, including their recommendations, on this evidence basis.

METHODS

Targeted searches for literature (since 2016) on main risk factors for cannabis-related adverse health outcomes modifiable by the user-individual were conducted. Topical areas were informed by previous LRCUG content and expanded upon current evidence. Searches preferentially focused on systematic reviews, supplemented by key individual studies. The review results were evidence-graded, topically organized and narratively summarized; recommendations were developed through an iterative scientific expert consensus development process.

RESULTS

A substantial body of modifiable risk factors for cannabis use-related health harms were identified with varying evidence quality. Twelve substantive recommendation clusters and three precautionary statements were developed. In general, current evidence suggests that individuals can substantially reduce their risk for adverse health outcomes if they delay the onset of cannabis use until after adolescence, avoid the use of high-potency (THC) cannabis products and high-frequency/-intensity of use, and refrain from smoking-routes for administration. While young people are particularly vulnerable to cannabis-related harms, other sub-groups (e.g., pregnant women, drivers, older adults, those with co-morbidities) are advised to exercise particular caution with use-related risks. Legal/regulated cannabis products should be used where possible.

CONCLUSIONS

Cannabis use can result in adverse health outcomes, mostly among sub-groups with higher-risk use. Reducing the risk factors identified can help to reduce health harms from use. The LRCUG offer one targeted intervention component within a comprehensive public health approach for cannabis use. They require effective audience-tailoring and dissemination, regular updating as new evidence become available, and should be evaluated for their impact.

Prenatal exposure to maternal, but not paternal, tobacco smoking is associated with smoking in adolescence

BACKGROUND

Mounting epidemiological evidence suggests an association between prenatal tobacco exposure and an increased risk of tobacco smoking in offspring. However, it is uncertain whether the association is due to the intrauterine or shared environmental exposures.

METHODS

Study participants were from the Raine Study, a prospective birth cohort study based in Perth, Western Australia (N = 2730). Tobacco smoking in adolescents, at age 17 years, was measured using a self-reported questionnaire. Log-binomial regression was used to estimate the relative risks (RRs) of tobacco smoking in offspring exposed to maternal prenatal tobacco use during the first and third trimesters of pregnancy. We have also calculated the E-values to investigate the potential effect of unmeasured confounding. Paternal smoking during pregnancy was used as a negative control for comparison.

RESULTS

A total of 1210 mothers-offspring pairs were included in the final analysis. After controlling for potential confounders, we found increased risks of tobacco smoking in offspring exposed to maternal prenatal tobacco use during the first trimester [RR 1.50 (95% CI: 1.13-1.97)] (E-value for point estimate = 2.37) and during both trimesters of pregnancy [RR 1.41 (95% CI: 1.03-1.89)] (E-value for point estimate = 2.17). However, we found insufficient statistical evidence for an association between paternal smoking during pregnancy and risk of tobacco smoking in offspring [RR 1.18 (95% CI: 0.84-1.67)].

CONCLUSION

Maternal prenatal tobacco exposure was associated with an increased risk of tobacco smoking in offspring at the age of 17 years. Tobacco smoking cessation at the early stages of gestation may reduce the risk of tobacco smoking in the next generation.

Prenatal THC exposure produces a hyperdopaminergic phenotype rescued by pregnenolone

Increased legal availability of cannabis has led to a common misconception that it is a safe natural remedy for, amongst others, pregnancy-related ailments like morning sickness. Emerging clinical evidence, however, indicates that prenatal cannabis exposure (PCE) predisposes offspring to various neuropsychiatric disorders linked to aberrant dopaminergic function. Yet, our knowledge of how cannabis exposure affects the maturation of this neuromodulatory system remains limited. Here, we show that male, but not female, offspring of Δ⁹-tetrahydrocannabinol (THC)-exposed dams, a rat PCE model, exhibit extensive molecular and synaptic changes in dopaminergic neurons of the ventral tegmental area, including altered excitatory-to-inhibitory balance and switched polarity of long-term synaptic plasticity. The resulting hyperdopaminergic state leads to increased behavioral sensitivity to acute THC during pre-adolescence. The FDA-approved neurosteroid pregnenolone rescues synaptic defects and normalizes dopaminergic activity and behavior in PCE offspring, suggesting a therapeutic approach for offspring exposed to cannabis during pregnancy.