by Paul Armentano
February 9, 2015
from AlterNet Website

Spanish version

Five new cannabis-centric studies

warrant major attention.
 

Scientific discoveries are published almost daily in regard to the healing properties of the cannabis.

But most of these findings appear solely in subscription-only peer-reviewed journals and, therefore, go largely unnoticed by the mainstream media and by the public.

Here are five just-published cannabis-centric studies that warrant attention. 

Men Who Smoke Pot Possess a Reduced Risk of Bladder Cancer
 
Is cannabis use protective against the development of certain types of cancer?

The findings of a just released study in the journal Urology imply that it might be. 
 
Investigators at the Kaiser Permanente Los Angeles Medical Center, Department of Neurology assessed the association of cannabis use and tobacco smoking on the risk of bladder cancer in a multiethnic cohort of more than 80,000 men aged 45 to 69 years old over an 11-year period.

The results?

While men who smoked cigarettes possessed a 1.5-fold increased risk of cancer, those who only smoked pot possessed a 45 percent reduced risk of being diagnosed with the disease. 

"After adjusting for age, race or ethnicity, and body mass index, using tobacco only was associated with an increased risk of bladder cancer (hazard regression 1.52) whereas cannabis use was only associated with a 45 percent reduction in bladder cancer incidence (HR 0.55)," investigators reported.

The study is not the first time that researchers have identified an inverse association between marijuana use and the development of cancer.

In 2009, Brown University researchers similarly reported that the moderate long-term use of marijuana was associated with a reduced risk of head and neck cancers in a multi-center cohort involving over 1,000 subjects.

In addition, the largest case-controlled study ever to investigate the respiratory effects of marijuana smoking found no positive association between inhaling pot and lung cancer risk.

"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," pulmonologist Dr. Donald Tashkin, Professor Emeritus at the David Geffen School of Medicine at UCLA told The Washington Post.

 

"What we found instead was no association at all, and even a suggestion of some protective effect."

Long-Term Pot Exposure Isn't Damaging to Lung Health

All smoke is not created equal. 
 
Unlike tobacco smoking, the inhalation of marijuana cigarettes - even long-term - is not associated with significant adverse changes in pulmonary health, according to data published online in December in the journal Annals of the American Thoracic Society.

Investigators at Emory University in Atlanta assessed marijuana smoke exposure and lung health in a large representative sample of US adults age 18 to 59. Researchers reported that cannabis exposure was not associated with FEV1 (forced expiratory volume) decline or deleterious change in spirometric values of small airways disease.

They further reported that marijuana smoke exposure may be associated with some protective lung effects among long-term smokers of tobacco, acknowledging,

 "[T]he pattern of marijuana's effects seems to be distinctly different when compared to that of tobacco use."

Their findings are similar to those of a 2013 literature review, published in the same journal, which concluded:

"[H]abitual use of marijuana alone does not appear to lead to significant abnormalities in lung function. Findings from a limited number of well-designed epidemiological studies do not suggest an increased risk of either lung or upper airway cancer from light or moderate use...

 

Overall, the risks of pulmonary complications of regular use of marijuana appear to be relatively small and far lower than those of tobacco smoking."

Alcohol, Not Pot, Alters the Brain
 
It was less than a year ago when the mainstream media was chock-full of headlines like this one: 'Brain changes associated with casual marijuana use in young adults, study finds.' 

But a funny thing happened when a team of scientists from the University of Colorado and the University of Kentucky tried to replicate these results in a larger, more well-controlled cohort of subjects. 
 

They couldn't.

"We acquired high-resolution MRI scans, and investigated group differences in gray matter using voxel-based morphometry, surface-based morphometry, and shape analysis in structures suggested to be associated with marijuana use, as follows: the nucleus accumbens, amygdala, hippocampus, and cerebellum," researchers summarized in the January 28 edition of The Journal of Neuroscience. 

 

"No statistically significant differences were found between daily users and nonusers on volume or shape in the regions of interest. Effect sizes suggest that the failure to find differences was not due to a lack of statistical power, but rather was due to the lack of even a modest effect."

They concluded,

"In sum, the results indicate that, when carefully controlling for alcohol use, gender, age, and other variables, there is no association between marijuana use and standard volumetric or shape measurements of subcortical structures…

 

[I]t seems unlikely that marijuana use has the same level of long-term deleterious effects on brain morphology as other drugs like alcohol."

Marijuana Use Doesn't Lead to Depression

"Regular use of marijuana has also been linked to depression, anxiety, and a loss of drive or motivation."

So says the online publication, 'Marijuana - Facts for Teens,' published by the US National Institute on Drug Abuse.

But is this claim true? No, according to longitudinal data published online ahead of print in the Journal of Affective Disorders, which reports that future incidences of major depression are not higher among cannabis users compared to nonusers.
 
Investigators concluded,

"Our results do not support a longitudinal association between cannabis use and increased incidence of MDD (major depressive disorder); rather, they indicate an inverse relationship between the two, which may be attributed to self-medication factors."

Previous studies have similarly dismissed the notion that pot use is associated with increased suicide risk.

Specifically, a 2013 study published in the American Journal of Public Health reported a drop in suicide rates in states that had legalized marijuana compared to those that had not, finding:

"Suicides among men aged 20 through 39 years fell after medical marijuana legalization compared with those in states that did not legalize.

 

The negative relationship between legalization and suicides among young men is consistent with the hypothesis that marijuana can be used to cope with stressful life events."

Marijuana Possesses a Unique Margin of Safety Compared to Other legal and Illegal Drugs
 
Despite the US federal government's ongoing insistence that pot is one of the most dangerous substances known to man, an objective review of the plant's safety profile finds that it is comparably safer than most other drugs, particularly alcohol. 
 
Writing in Nature.com this past January, an international team of German and Canadian researchers published a comparative risk assessment of the toxicity of tobacco, alcohol, and cannabis (Comparative Risk Assessment of Alcohol, Tobacco, Cannabis and other Illicit Drugs Using the Margin of Exposure Approach).

Their evaluation concluded that the risks of cannabis have likely been "overestimated" while the dangers associated with booze "have been commonly underestimated."
 
They concluded:

"[Our] results point to risk management prioritization toward alcohol and tobacco rather than illicit drugs… [and] suggest a strict legal regulatory approach [for cannabis] rather than the current prohibition approach."