The mainstream media launched into a reefer mad frenzy this week after researchers from Harvard University in Boston and Northwestern University in Chicago published the results of a neuroimaging study assessing the brains of a small cohort of regular marijuana smokers and non-users. The brain scans identified various differences between the two groups in three aspects of brain morphometry: gray matter density, volume, and shape. These differences triggered dozens of high-profile media outlets to lose their collective minds. Here’s a sampling:
Yet despite the sensationalist headlines, the study itself was hardly newsworthy. Decades of research pertaining to the potential residual adverse effects of cannabis on brain cognition have failed to support the notion that marijuana poses any sort of permanent brain deficits. And as I write today on Alternet.org, this study similarly failed to report any sort of real-world adverse consequences associated with cannabis use:
[excerpt] Using high–resolution MRI imaging, scientists identified specific changes in particular regions of the brain that they inferred were likely due to marijuana exposure. (Since researchers only performed a single MRI session, they could not say definitively whether these changes were, in fact, caused by cannabis or whether they existed prior to subjects’ use of the plant.) Notably, however, these changes did not appear to be associated with any overt adverse effects in subjects’ actual cognition or behavior. (Separate studies assessing youth use of legal intoxicants, such as nicotine and alcohol, have also been associated with documented changes in brain structure. Ditto for caffeine intake in preclinical models. These findings have received far less media attention.)
Both the cases (20 marijuana users) and controls (20 nonusers) in the study were recruited from local universities, undermining the notion that the alleged ‘brain damaged potheads’ were any more academically challenged than their non-using peers. Further, as summarized by HealthDay: “Psychiatric interviews revealed that the pot smokers did not meet criteria for drug dependence. For example, marijuana use did not interfere with their studies, work or other activities, and they had not needed to increase the amount they used to get the same high.”
In other words, case subjects and controls appeared to function similarly in their professional and academic endeavors.
You can read the full text of my response here.
Fortunately, my critique of this latest paper — and in particular the mainstream media’s sensationalist and erroneous coverage of its findings — is far from the only one. Below are links to several other excellent analyses:
Bits of DNA (blog): Does researching casual marijuana use cause brain abnormalities?
Those who report consuming cannabis two or three times per week are less likely to engage in at risk drinking behavior, according to data published online in The American Journal of Addictions.
Investigators from Sweden’s Lund University, Department of Clinical Sciences, analyzed data from a nationwide survey on alcohol and drug use conducted by the National Institute of Public Health. Over 22,000 respondents between the ages of 15 and 64 participated in the survey.
Researchers reported that frequent cannabis consumers (defined as having used cannabis two or three times per week) were less likely to engage in hazardous drinking practices compared to infrequent users (those who reported having consumed cannabis fewer than four times per month).
They concluded: “In the present study, it has been shown that, in the Swedish general population, cannabis use is associated with a higher prevalence of other illicit drug use and hazardous alcohol use. Among cannabis users, frequent cannabis use is associated with a higher prevalence of other illicit drug use and a lower prevalence of hazardous alcohol use when compared to occasional cannabis use. … … The inverse relationship between the frequency of cannabis use and hazardous drinking has not been reported before to our knowledge. … This may indicate that cannabis users and alcohol users are different groups, albeit with a high degree of overlap between groups, with different characteristics and clinical needs.”
A review paper published in February in the journal Alcohol and Alcoholism similarly acknowledged that some cannabis consumers likely substitute the plant for alcohol. It concluded: “While more research and improved study designs are needed to better identify the extent and impact of cannabis substitution on those affected by AUD (alcohol use disorders), cannabis does appear to be a potential substitute for alcohol. Perhaps more importantly, cannabis is both safer and potentially less addictive than benzodiazepines and other pharmaceuticals that have been evaluated as substitutes for alcohol.”
An abstract of the study, “Alcohol and drug use in groups of cannabis users: Results from a survey on drug use in the Swedish general population,” appears here.
The enactment of medicinal cannabis laws is not associated with any rise in statewide criminal activity and may even be related to reductions in incidences of violent crime, according to data published online in the journal PLoS ONE.
Researchers at the University of Texas at Dallas tracked crime rates across all 50 states between the years between 1990 and 2006, a time period during which 11 states legalized marijuana for medical use. Authors reviewed FBI data to determine whether there existed any association between the passage of medicinal cannabis laws and varying rates of statewide criminal activity, specifically reported crimes of homicide, rape, robbery, assault, burglary, larceny, and auto theft.
Investigators reported that the passage of medical marijuana laws was not associated with an increase in any of the seven crime types assessed, but that liberalized laws were associated with decreases in certain types of violent crime.
“The central finding gleaned from the present study was that MML (medical marijuana legalization) is not predictive of higher crime rates and may be related to reductions in rates of homicide and assault,” authors reported. “Interestingly, robbery and burglary rates were unaffected by medicinal marijuana legislation, which runs counter to the claim that dispensaries and grow houses lead to an increase in victimization due to the opportunity structures linked to the amount of drugs and cash that are present. Although, this is in line with prior research suggesting that medical marijuana dispensaries may actually reduce crime in the immediate vicinity.”
Researchers concluded: “Medical marijuana laws were not found to have a crime exacerbating effect on any of the seven crime types. On the contrary, our findings indicated that MML precedes a reduction in homicide and assault. … In sum, these findings run counter to arguments suggesting the legalization of marijuana for medical purposes poses a danger to public health in terms of exposure to violent crime and property crimes.”
Full text of the study, “The Effect of Medical Marijuana Laws on Crime: Evidence from State Panel Data, 1990-2006,” appears online here.
The poll, which questioned over 11,000 law enforcement officers regarding their opinions on drug policy, revealed that just over 64% believed our marijuana laws needed to be relaxed in some form. When asked “Do you believe possession of marijuana for personal use should…” and presented with several options, 35.68% of respondents stated that marijuana be legalized, regulated and taxed, 10.84% chose that it should be be legalized for medical reasons and with a doctor’s prescription only, 14.24% said it should continue to be illegal but only punished via fines (no incarceration), and 3.68% said marijuana should simply be decriminalized. Only 34.7% believed marijuana should continue to be illegal with the criminal penalties that are currently in place.
“This poll reveals that support for marijuana prohibition is eroding even amongst those who are serving on the front lines enforcing it,” stated NORML Communications Director Erik Altieri, “When a majority of the American people and most of those tasked with implementing a law disagree with it in principle, it is time to change that law.”
You can view the full results of this survey here.
“Prohibition cannot be enforced for the simple reason that the majority of the American people do not want it enforced and are resisting its enforcement. That being so, the orderly thing to do under our form of government is to abolish a law that cannot be enforced, a law which the people of the country do not want enforced.” – New York Mayor Fiorello La Guardia on alcohol prohibition.
An estimated 70 percent of physicians acknowledge the therapeutic qualities of cannabis and over half believe that the plant should also be legal for medical purposes, according to survey data released this week by WebMD/Medscape.
Sixty-nine percent of respondents say that cannabis can help in the treatment of specific diseases and 67 percent say that the plant should be available as a legal therapeutic option for patients.
Oncologists and hematologists were most likely to express support for the use of cannabis for medical purposes, with 82 percent of those surveyed endorsing the plant’s therapeutic use. Rheumatologists (54 percent) were least likely to say the cannabis provides therapeutic benefits.
Over 1,500 physicians representing more than 12 specialty areas participated in the survey which possesses a margin of error of +/- 2.5 percent.