Marijuana and the Lung: Evolving Understandings

Cardiovascular and Respiratory Effects of Cannabis Use by Route of Administration: A Systematic Review

Aim: Knowledge of the cardiovascular and respiratory effects of cannabis use by route of administration is unclear. This evidence is necessary to increase clinical and public health awareness given the recent trend in cannabis legalization, normalization, and surge in the availability and usage of various forms of cannabis products. Methods: Search was conducted in Web of Science, ProQuest, Psych INFO, Scopus, Embase, and Medline databases, and subsequently in the references of retrieved articles. Peer-reviewed articles published between 2009 and 2023, that reported on cardiovascular and respiratory effects of cannabis use by route of administration were included. Studies with no report of the route of administration and combined use of other illicit substances were excluded. The review was guided by Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Results: Of the 1873 articles retrieved, 42 met inclusion criteria encompassing six case reports, 21 reviews, and 15 empirical studies. Four administration routes were identified: smoking, vaping, oral ingestion, and dabbing. Smoking was the most common route of administration and was associated with both respiratory effects, such as bronchitis, dyspnea, and chronic obstructive lung disease, and cardiovascular effects including tachycardia, ventricular arrhythmias, and myocardial infarction. Cannabis edibles were associated with minimal respiratory effects. Tachycardia was the most common cardiovascular effect and was associated with all routes of administration. Conclusion: Cannabis use does cause cardiovascular and respiratory effects, but the conclusion remains tentative of the cardiovascular and respiratory effects by route of administration due to methodological limitations of the studies.

Effectiveness of Medical Cannabis for the Treatment of Depression: A Naturalistic Outpatient Study

BACKGROUND

There is a lack of studies on the course and effectiveness of medical cannabis in the treatment of major depressive disorder (MDD).

METHODS

Retrospective longitudinal (18 weeks) study of n=59 outpatients with MDD, treated with medical cannabis via a telemedical platform. Previous treatment with antidepressant medication was required for inclusion into the study. Standardized data collection was carried out at entry and during monthly consultations. Severity of depression was measured on a 0-10 point rating scale. Side-effects were assessed by a checklist.

RESULTS

Patients were 20-54 years old; 72.9% were male; one third reported times of regular cannabis consumption within the previous five years. Drop-out rate was 22% after 18 weeks. Mean severity of depression decreased from 6.9 points (SD 1.5) at entry to 3.8 points (2.7) at week 18 (baseline observation carried forward; 95% CI for the mean difference: 2.4 to 3.8; p<0.001). A treatment response (>50% reduction of the initial score) was seen in 50.8% at week 18. One third of patients complained about side effects, none was considered as severe. Concomitant antidepressant medication (31% of patients) was not associated with outcome.

CONCLUSIONS

Medical cannabis was well tolerated and dropout rate was comparable to those in clinical trials of antidepressant medication. Patients reported a clinically significant reduction of depression severity. Further research on the effectiveness of medical cannabis for MDD seems warranted. Risks of this medication, such as sustaining or inducing a cannabis use disorder, or side effects such as poor concentration, must be taken into consideration.

The Association Between Tobacco and Cannabis Use and the Age of Onset of Depression and Anxiety Symptoms: Among Adolescents and Young Adults

INTRODUCTION

No studies have prospectively explored the association between the use of tobacco or cannabis use and the age of onset of depressive or anxiety symptoms, and no studies have identified the peak ages and ranges of onset of these symptoms among tobacco and/or cannabis users.

AIMS AND METHODS

This is a secondary analysis of Texas Adolescent Tobacco and Marketing Surveillance System data, waves 9-14 (2019-20121). Participants were in 10th grade, 12th grade, and 2 years post-high school (HS) at baseline (wave 9). Interval-censoring multivariable Cox proportional hazards models were fit to assess differences in the estimated age of onset of depression and anxiety by tobacco and cannabis use while adjusting for covariates.

RESULTS

We found that lifetime or ever cigarette, e-cigarette, and cannabis use had an increased risk of an earlier age of onset of depressive and anxiety symptoms across the three cohorts, and the youngest cohort was the most differentially impacted by substance use. Between ages 18 to 19 years in the 10th-grade cohort, between ages 20 to 21 years in the 12th-grade cohort, and between ages 22 to 23 years in the post-HS cohort, the estimated hazard function (or cumulative incidence) for reporting depressive and anxiety symptoms almost doubled among lifetime cigarette, e-cigarette, and cannabis users.

CONCLUSIONS

Tobacco and cannabis users should be screened for mental health problems at an earlier age, especially those aged 18 years and younger, and provided with age- and culturally appropriate resources to prevent or delay the onset of anxiety and/or depression symptoms.

IMPLICATIONS

The study's findings indicate that tobacco and cannabis use is directly linked to the early onset of depressive and anxiety symptoms among youth. This highlights the significance of early screening and substance use interventions, particularly for youth aged 18 years and younger, as they are disproportionately affected by both substance use and mental health problems. School-based interventions that are age- and culturally appropriate hold promise as they enable youth to seek professional help early, and in a supportive environment. Intervening early in substance shows promise in reducing the likelihood of developing mental health problems at a young age.

Should oncologists trust cannabinoids?

Cannabis enjoyed a "golden age" as a medicinal product in the late 19th, early 20th century, but the increased risk of overdose and abuse led to its criminalization. However, the 21st century have witnessed a resurgence of interest and a large body of literature regarding the benefits of cannabinoids have emerged. As legalization and decriminalization have spread around the world, cancer patients are increasingly interested in the potential utility of cannabinoids. Although eager to discuss cannabis use with their oncologist, patients often find them to be reluctant, mainly because clinicians are still not convinced by the existing evidence-based data to guide their treatment plans. Physicians should prescribe cannabis only if a careful explanation can be provided and follow up response evaluation ensured, making it mandatory for them to be up to date with the positive and also negative aspects of the cannabis in the case of cancer patients. Consequently, this article aims to bring some clarifications to clinicians regarding the sometimes-confusing various nomenclature under which this plant is mentioned, current legislation and the existing evidence (both preclinical and clinical) for the utility of cannabinoids in cancer patients, for either palliation of the associated symptoms or even the potential antitumor effects that cannabinoids may have.

Modulation of pulmonary immune function by inhaled cannabis products and consequences for lung disease

The lungs, in addition to participating in gas exchange, represent the first line of defense against inhaled pathogens and respiratory toxicants. Cells lining the airways and alveoli include epithelial cells and alveolar macrophages, the latter being resident innate immune cells important in surfactant recycling, protection against bacterial invasion and modulation of lung immune homeostasis. Environmental exposure to toxicants found in cigarette smoke, air pollution and cannabis can alter the number and function of immune cells in the lungs. Cannabis (marijuana) is a plant-derived product that is typically inhaled in the form of smoke from a joint. However, alternative delivery methods such as vaping, which heats the plant without combustion, are becoming more common. Cannabis use has increased in recent years, coinciding with more countries legalizing cannabis for both recreational and medicinal purposes. Cannabis may have numerous health benefits owing to the presence of cannabinoids that dampen immune function and therefore tame inflammation that is associated with chronic diseases such as arthritis. The health effects that could come with cannabis use remain poorly understood, particularly inhaled cannabis products that may directly impact the pulmonary immune system. Herein, we first describe the bioactive phytochemicals present in cannabis, with an emphasis on cannabinoids and their ability to interact with the endocannabinoid system. We also review the current state-of-knowledge as to how inhaled cannabis/cannabinoids can shape immune response in the lungs and discuss the potential consequences of altered pulmonary immunity. Overall, more research is needed to understand how cannabis inhalation shapes the pulmonary immune response to balance physiological and beneficial responses with potential deleterious consequences on the lungs.