by Paul Armentano
February 9, 2015
Five new cannabis-centric
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
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
Is cannabis use protective against the development of certain types
The findings of
a just released study in the journal Urology imply that it might
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
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
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.
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
"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
Their findings are similar to those of
a 2013 literature review, published in the same journal, which
"[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
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
"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."
"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
[I]t seems unlikely that marijuana use has the
same level of long-term deleterious effects on brain morphology
as other drugs like alcohol."
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
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
"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
Previous studies have
similarly dismissed the notion that pot use is associated with
increased suicide risk.
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."
Possesses a Unique Margin of Safety Compared to Other legal and
Despite the US federal government's
ongoing insistence that pot is one of the most
substances known to man, an objective review of the plant's safety
profile finds that it is comparably safer than most other drugs,
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."
"[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."