Researchers from Texas A&M University and the University of Florida, Gainesville evaluated drug use patterns from a nationally representative sample of 2,835 12th graders.
Authors found that youth use of alcohol most often preceded the use of tobacco or marijuana. They also reported subjects’ age of alcohol initiation is the strongest predictor of later polydrug use.
“Alcohol is the most commonly used substance, and the majority of polysubstance using respondents consumed alcohol prior to tobacco or marijuana initiation,” they reported. “Respondents initiating alcohol use in sixth grade reported significantly greater lifetime illicit substance use and more frequent illicit substance use than those initiating alcohol use in ninth grade or later.”
They concluded, “Our results … assert that the earlier one initiates alcohol use, the more likely that they will engage in future illicit substance use.”
The findings are inconsistent with recent claims made by several prominent lawmakers that cannabis is a ‘gateway’ to later substance abuse.
Studies conducted by the RAND Corporation and others have previously dismissed any alleged causal role of marijuana as a gateway to subsequent illicit drug abuse, finding, “There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other drugs.”
An abstract of the study, “Prioritizing Alcohol Prevention: Establishing Alcohol as the Gateway Drug and Linking Age of First Drink With Illicit Drug Use,” appears online here.
Marijuana use by adolescents is not associated with lower IQ or poorer educational performance once adjustments are made for potential confounders, specifically cigarette smoking, according to longitudinal data published online ahead of print in the Journal of Psychopharmacology.
British investigators assessed the relationship between cumulative cannabis use and IQ at the age of 15 and educational performance at the age of 16 in a cohort of 2,235 adolescents.
After researchers adjusted for potentially confounding variables, such as childhood depression and cigarette use, they reported, “[T]hose who had used cannabis [greater than or equal to] 50 times did not differ from never-users on either IQ or educational performance.”
By contrast, teen cigarette smoking was associated with poorer educational outcomes even after researchers adjusted for other confounding variables.
Researchers concluded, “In summary, the notion that cannabis use itself is causally related to lower IQ and poorer educational performance was not supported in this large teenage sample.”
A widely publicized New Zealand study published in 2012 in The Proceedings of the National Academy of Sciences reported that frequent use of cannabis by those under the age of 18 was associated with lower IQ by age 38. However, a separate review of the data published later in the same journal suggested that the changes were likely the result of socioeconomic differences, not cannabis use.
More recently, the results of a 2015 study in the journal Drug and Alcohol Dependence reported that the effects of persistent adolescent cannabis use on academic performance “became non-significant after controlling for persistent alcohol and tobacco use.”
Full text of the study, “Are IQ and educational outcomes in teenagers related to their cannabis use? A prospective cohort study,” appears online here.
Cannabis administration is associated with decreased migraine headache frequency, according to data published online ahead of print in the journal Pharmacotherapy.
Investigators at the University of Colorado, Skaggs School of Pharmacy and Pharmaceutical Sciences retrospectively assessed cannabis’ effects on monthly migraine headache frequency in a group of 121 adults. Study participants had a primary diagnosis of migraine headache, had been recommended cannabis by a physicians for migraine treatment, and had participated in at least one follow up medical visit.
Authors reported that 85 percent of subjects reported a decrease in migraine frequency and 12 percent indicated that the use of cannabis prior to migraine onset would abort headaches.
“Migraine headache frequency decreased from 10.4 to 4.6 headache per month with the use of medical marijuana,” researchers concluded. “Further research should be performed to determine if there is a preferred delivery method, dose, and strain of medical marijuana for migraine headache therapy as well as potential long-term effects of medical marijuana.”
Although case reports have previously documented the effect of cannabinoids for migraine relief, no prospective trials have yet to evaluate cannabis use in migraine patients. Nonetheless, scientists for some time have theorized that cannabinoids may play a role in migraine regulation. Writing in 2007 in the European Journal of Critical Pharmacology, Italian researchers reported that patients with chronic migraines possessed significantly lower levels of the endogenous cannabinoids anandamide and 2-arachidonylglycerol (2-AG) in their platelets compared to age-matched controls. “These data support the potential involvement of a dysfunctioning of the endocannabinoid and serotonergic systems in the pathology of chronic migraine and medication-overuse headaches,” authors concluded.
The abstract of the study, “Effects of medical marijuana on migraine headache frequency in an adult population,” appears online here.
Long-term exposure to tobacco smoke is demonstrably harmful to health. According to the United States Center for Disease Control, tobacco smoking is the leading cause of preventable death in the United States, and chronic exposure to tobacco smoke is linked to increased incidences of cancer as well as vascular disease. Inhaling tobacco smoke is also associated with a variety of adverse pulmonary effects, such as COPD (chronic obstructive pulmonary disease).
Does smoking cannabis pose similar dangers to lung health? According to a number of recent scientific findings, marijuana smoke and tobacco smoke vary considerably in their health effects. So then why are lawmakers in various states, such a Minnesota and New York, imposing new restrictions explicitly prohibiting the inhalation of herbal preparations of cannabis?
Marijuana Smoke vs. Tobacco Smoke
Writing in the Harm Reduction Journal in 2005, noted cannabis researcher Robert Melamede explained that although tobacco smoke and marijuana smoke have some similar chemical properties, the two substances possess different pharmacological activities and are not equally carcinogenic. Specifically, he affirmed that marijuana smoke contains multiple cannabinoids – many of which possess anti-cancer activity – and therefore likely exerts “a protective effect against pro-carcinogens that require activation.” Melamede concluded, “Components of cannabis smoke minimize some carcinogenic pathways whereas tobacco smoke enhances some.”
Marijuana Smoke and Cancer
Consequently, studies have so far failed to identify an association between cannabis smoke exposure and elevated risks of smoking-related cancers, such as cancers of the lung and neck. In fact, the largest case-controlled study ever to investigate the respiratory effects of marijuana smoking reported that cannabis use was not associated with lung-related cancers, even among subjects who reported smoking more than 22,000 joints over their lifetime. Summarizing the study’s findings in The Washington Post, pulmonologist Dr. Donald Tashkin, Professor Emeritus at the David Geffen School of Medicine at UCLA, concluded: “We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use. What we found instead was no association at all, and even a suggestion of some protective effect.”
A meta-analysis of additional case-control studies, published in the International Journal of Cancer in 2014, similarly reported, “Results from our pooled analyses provide little evidence for an increased risk of lung cancer among habitual or long-term cannabis smokers,” while a 2009 Brown University study determined that those who had a history of marijuana smoking possessed a significantly decreased risk of head and neck cancers as compared to those subjects who did not.
Marijuana Smoke and Pulmonary Function
According to a 2015 study conducted at Emory University in Atlanta, the inhalation of cannabis smoke, even over extended periods of time, is not associated with detrimental effects on pulmonary function, such as forced expiratory volume (FEV1) and forced vital capacity (FCV). Assessing marijuana smoke exposure and lung health in a large representative sample of U.S. adults, age 18 to 59, they maintained, “The pattern of marijuana’s effects seems to be distinctly different when compared to that of tobacco use.” Subjects had inhaled the equivalent of one marijuana cigarette per day for 20 years, yet did not experience FEV1 decline or deleterious change in spirometric values of small airways disease.
Marijuana Smoke and COPD
While tobacco smoking is recognized as a major risk factor for the development of COPD – a chronic inflammation of the airways that may ultimately result in premature death – marijuana smoke exposure (absent concurrent tobacco smoke exposure) appears to present little COPD risk. In 2013, McGill University professor and physician Mark Ware wrote in the journal Annals of the American Thoracic Society: “Cannabis smoking does not seem to increase risk of chronic obstructive pulmonary disease or airway cancers… Efforts to develop cleaner cannabinoid delivery systems can and should continue, but at least for now, (those) who smoke small amounts of cannabis for medical or recreational purposes can breathe a little bit easier.”
Mitigating Marijuana Smoke Exposure
The use of a water-pipe filtration system primarily cools cannabis smoke, which may reduce throat irritation and cough. However, this technology is not particularly efficient at eliminating the potentially toxic byproducts of combustion or other potential lung irritants.
By contrast, vaporization heats herbal cannabis to a point where cannabinoid vapors form, but below the point of combustion – thereby reducing the intake of combustive smoke or other pollutants, such as carbon monoxide and tar. Observational studies show that vaporization allows consumers to experience the rapid onset of effect while avoiding many of the associated respiratory hazards associated with smoking – such as coughing, wheezing, or chronic bronchitis. Clinical trials also report that vaporization results in the delivery of higher plasma concentrations of THC (and likely other cannabinoids) compared to smoked cannabis. As a result, the authors affiliated with the University of California Center for Medicinal Cannabis Research and elsewhere now acknowledge that vaporizers provide a “safe and effective” way to for consumers to inhale herbal cannabis.
The Bottom Line
Based on this scientific record, it makes little sense for lawmakers to impose legislative bans on herbal cannabis products, such as those that presently exist for patients in Minnesota and New York and which are now being proposed in several other states (e.g., Georgia and Pennsylvania). Oral cannabis preparations, such as capsules and edibles, possess delayed onset compared to inhaled herbal cannabis, making these options less suitable for patients desiring rapid symptomatic relief. Further, oral administration of cannabis-infused products is associated with significantly greater bioavailability than is inhalation – resulting in more pronounced variation in drug effect from dose to dose (even in cases where the dose is standardized). These restrictions unnecessarily limit patients’ choices and deny them the ability to obtain rapid relief from whole-plant cannabis in a manner that has long proven to be relatively safe and effective.
Marijuana consumers do not typically use cannabis and alcohol in combination with one another, regardless of whether they are consuming cannabis for medicinal or social purposes, according to data published online ahead of print in the journal Addiction.
Investigators with the RAND Drug Policy Research Center and the University of California, Irvine surveyed marijuana use patterns among participants between the ages of 18 and 91 in four states: Colorado, New Mexico, Oregon, and Washington. (The use of marijuana for medicinal purposes is legal in New Mexico, while laws in Colorado, Oregon, and Washington permit adults to possess and purchase cannabis for both medicinal and/or recreational purposes.)
Authors reported, ”Individuals who use cannabis do not commonly use it with alcohol, irrespective of whether they are consuming cannabis recreationally or medically.” They concluded, “Fewer than one in five recreational users report simultaneous use of alcohol and cannabis most or all of the time and less than three percent of medicinal users report frequent simultaneous use of alcohol and cannabis.”
An abstract of the study, “A baseline view of cannabis use among legalizing states and their neighbors,” appears online here.