Cannabis protects men against bladder and smart girls do more drugs

Jacob Schor ND, FABNO

May 30, 2013



Clorado’s legalization of marijuana has me paying more attention to research publications related to cannabis. Here we discuss two interesting related topics. The first is that marijuana use is linked to lower risk of bladder cancer. The second is that at least in women, higher IQ is linked to increased drug use.


Pot lowers risk of bladder cancer:

A recent study reports that cannabis use is linked to a significantly decreased risk for bladder cancer in men.


The study, presented a few days ago at the American Urologogy Association’s 2013 Annual meeting found a 45% lower risk of bladder cancer in men who used marijuana compred to those who don’t.

This association was present even after adjusting for age, weight, and race.


In a communication with OncologyNet, the study’s lead author Anil Thomas wrote,

“Bladder cancer is one of the most prevalent genitourinary malignancies with an estimated 72,570 new cases and 15,210 cancer-related deaths per year in the United States, and it is the fourth most common malignancy in men….. Importantly, advanced bladder cancer is inherently challenging to treat due to its associated high mortality and lack of effective systemic therapies.”


“To explore the relationship between cannabis and bladder cancer, Dr. Thomas and colleagues evaluated the incidence of bladder cancer among 82,050 men aged 45 years to 69 years enrolled in the California Men’s Health Study. All men had completed questionnaires including information on demographic and lifestyle factors such as smoking history and cannabis usage. Men who did not smoke were used as a reference group.

Results indicated that 41% of participants reported cannabis use; 57%, tobacco use; 27%, both; and 29%, neither. During the 11 years of follow-up, 279 participants (0.3%) developed bladder tumors. A significant difference was found between the number of cannabis users who developed bladder cancer and bladder cancer among men who did not report cannabis use (0.3% vs 0.4%; P < .001).

In contrast to cannabis use, which resulted in decreased risk for the disease (HR = 0.55; 95% CI, 0.31–1.00), use of tobacco was associated with an increased risk for bladder cancer (HR = 1.52; 95% CI, 1.12–2.07).


“Those using both cannabis and tobacco seemed to negate these effects with a smaller increase in their incidence of bladder cancer,” Dr. Thomas said.

After multivariate adjustment, men who reported only one or two uses of cannabis had no reduction in the incidence of bladder cancer; whereas, men using cannabis greater than 500 times had a reduction in their bladder cancer incidence hazard ratio (HR = 0.66, 95% CI, 0.36–1.21).” [1]




This possible benefit is curious especially in contrast to the report from last winter that cannabis increases risk of testicular cancer.


This contrast in effect illustrates the complexity of this plant’s actions and our inability to make generalizations about its health effects.


Tobacco and pot a bad mix:

Our daughter Sophie has recently returned from spending Paris and informed me this morning that the French have a different style of smoking marijuana. In Paris apparently it is customary to mix marijuana with tobacco and to smoke the combination. We won’t detail the reasons she came up with to justify this French practice style. Suffice to say the French have their reasons for many things that they do in what is considered a superior manner.


What is important is the report published last March by Underner et al that warns about this practice suggesting that it is more harmful than smoking either substance alone. Quoting from the abstract of the study: “One cigarette composed of cannabis and tobacco is much more harmful than a cigarette containing only tobacco. In cannabis smokers there is an increased incidence of respiratory symptoms and episodes of acute bronchitis. Cannabis produces a rapid bronchodilator effect; chronic use provokes a reduction in specific conductance and increase in airways resistance. ….. Cannabis smoke and tetrahydrocannabinol irritate the bronchial tree. They bring about histological signs of airways inflammation and alter the fungicidal and antibacterial activity of alveolar macrophages. Inhalation of cannabis smoke is a risk factor for lung cancer. Stopping smoking cannabis will bring about important benefits for lung function.” [2]



Thus mixing pot with tobacco sounds like a dumb idea, though of course we might rationalize that the cannabis will partially cancel out the increased risk of bladder cancer that is caused by smoking tobacco.


Smart girls smoke more pot:

Speaking of dumb ideas, there have been a series of papers by JW White from Cardiff University that report increased drug use in intelligent women.[3]    Their most recent paper, published in September 2012’s Annals of Epidemiology, linked high childhood IQ with greater drug use as adults. They studied 6,713 people who as 11 year-old children had their Iqs measured when they took part in 1958 National Child Development Survey. Their lifetime illegal drug use was then measured at 42 years of age.


White’s analysis of the data found that for every 1 standard deviation increase in IQ (15 point) there was a 30% increase in cannabis use, a 66% increase in cocaine use and a 79% increase in amyl nitrate use. These associations were not as clear in men.



White had a second study published in September 2013, but using data from a 1970 cohort. IQ levels had been tested at 5 and 10 years of age and drug use was surveyed when the cohort was 30 years olf.


Approximately 7,900 people were included in the analysis. Again the association between higher IQ and drug use was stronger in women then in men. Those women who were in the upper third of girls when ranked by IQ when five years old were more than twice as likely to report using cannabis at 30 years old than those who were in the lower third of the IQ rankings 25 years earlier.      (OR ((bottom vs top tertile)) =2.25, 95% CI 1.71 to 2.97)


Why would smart girls tend to do more drugs than dumb girls? One anonymous individual, who wishes who spoke off the record, summed it up as, “Oh cool now I can be spacy and stupid like everyone else around me.”


Perhaps the distinction between this IQ and drug use trend in men an women is related to differences in the need to fit into a social groups varying by sex. High intelligence may be considered a liability in some social settings and drugs provide a way to ‘… dumb this down so I can fit in.’





1. Cancer Network

Home of the Journal Oncology


Cannabis Linked to Decreased Bladder Cancer Risk

By Leah Lawrence | May 28, 2013


2. Rev Mal Respir. 2013 Apr;30(4):272-85. doi: 10.1016/j.rmr.2013.01.013. Epub 2013 Mar 19.

[Cannabis use and impairment of respiratory function].

[Article in French]


3. Ann Epidemiol. 2012 Sep;22(9):654-7. doi: 10.1016/j.annepidem.2012.06.001. Epub 2012 Jul 7.

Intelligence quotient in childhood and the risk of illegal drug use in middle-age: the 1958 National Child Development Survey.

White JW, Gale CR, Batty GD.