Correlations between cannabis use a... [Proc Natl Acad Sci U S A. 2013] - PubMed - NCBI

Now we see that the so-called research that the opponents of marijuana legalization were touting as "definitive proof" that marijuana use damages teen brains has been revealed as bogus with flawed methodology and deceptive causal inference drawn from premature evidence. The review of the pseudo-scientific deceit found that "the true effect (of marijuana on teen cognition) could be zero." So how did the original research team come up with such flawed results? By tailoring the study's parameters and subject population and protocol to give them the results they wanted. Why? Because bad science on marijuana gets excellent funding. With the turn in public opinion and the move by the first two states to legalize marijuana, be prepared to hear more and more desperate assertions drawn from bogus research in a pitiful effort to hide the truth about marijuana and how it benefits human health. 2013 Jan 14. [Epub ahead of print]

Correlations between cannabis use and IQ change in the Dunedin cohort are consistent with confounding from socioeconomic status.

Rogeberg O.


Does cannabis use have substantial and permanent effects on neuropsychological functioning? Renewed and intense attention to the issue has followed recent research on the Dunedin cohort, which found a positive association between, on the one hand, adolescent-onset cannabis use and dependence and, on the other hand, a decline in IQ from childhood to adulthood [Meier et al. (2012) Proc Natl Acad Sci USA 109(40):E2657-E2664]. The association is given a causal interpretation by the authors, but existing research suggests an alternative confounding model based on time-varying effects of socioeconomic status on IQ. A simulation of the confounding model reproduces the reported associations from the Dunedin cohort, suggesting that the causal effects estimated in Meier et al. are likely to be overestimates, and that the true effect could be zero. Further analyses of the Dunedin cohort are proposed to distinguish between the competing interpretations. Although it would be too strong to say that the results have been discredited, the methodology is flawed and the causal inference drawn from the results premature.

via Correlations between cannabis use a... [Proc Natl Acad Sci U S A. 2013] - PubMed - NCBI.

Marijuana may help binge-drinking brain - News - The Independent Collegian - University of Toledo student newspaper

A study was done to find out how much worse it is to smoke marijuana while binge drinking than to just binge drink alone. The government constantly funds such studies in a desperate attempt to prove that there is SOMETHING dangerous about marijuana. But, guess what! Surprise! Marijuana shields the brains of binge drinkers from the damage that alcohol causes. This is why I assert that marijuana should be made available on college campuses at any event where alcohol is served. Let's move people away from the deadly scourge of booze and toward the healing bliss of cannabis! The Independent Collegian

Marijuana may help binge-drinking brain                                           By Kevin Moore                                                                             Binge drinkers who also smoke marijuana may suffer less brain damage than drinkers who do not smoke marijuana, according to a recent study done by researchers at the University of California, San Diego and published by Neurotoxicology and Teratology magazine.The study, which was performed and published in late July, analyzed brain scans of 16 to 19-year-old males and females to compare the amount of white brain matter damage. White brain matter contains nerve fibers and is one of the two components of the central nervous system, according to the National Institutes of Health's Web site.The study compared the damage to white brain matter between those who regularly engage in binge drinking and marijuana usage to those who solely participated in binge drinking and those who did neither. For the purpose of this study, binge drinking was defined as having five drinks during one sitting for males and four drinks during one sitting for females.The results of the study showed those who only participated in binge drinking had damage in all eight sections of the brain, while those who used marijuana regularly only showed damage in three out of the eight sections. "Clearly, the marijuana group did better," said Director of Communication for the Marijuana Policy Project Bruce Mirken. "The marijuana plant is a heavy carrier of cannabinoids, of which there is much evidence to suggest that they can serve as a neural protector.

via Marijuana may help binge-drinking brain - News - The Independent Collegian - University of Toledo student newspaper.

Neuropsychopharmacology - Abstract of article: Functional Connectivity in Brain Networks Underlying Cognitive Control in Chronic Cannabis Users

Once again we see no harm to the brain from regular marijuana use, in fact this study presents evidence that connectivity in the brain is enhanced by long-term, chronic marijuana smoking. Unfortunately, hobbled by euphoranoia and marijuanaphobia, the authors speculate that these improvements in brain structure result from compensatory actions resulting from impairment by euphoria when in reality the improvement in brain structure is more likely the result of direct actions triggered by cannabinoids, especially THC. We know that THC has the amazing ability to stimulate the production of healthy new brain cells, a process known as neurogenesis, therefore it is not unreasonable to speculate that the improved connections in the brain result from the positive biochemical effects of this neuroprotective, neuroreparative cannabinoid. The powerful stigma associated with marijuana that was brainwashed into two generations with reefer madness campaigns supported by reams of pseudo-scientific data continues to blind researchers to the reality that cannabinoids are health-building and health-regulating compounds and that supplementing our naturally-produced supply of these vital compounds with cannabis or cannabis products vastly improves all aspects of human health. Functional Connectivity in Brain Networks Underlying Cognitive Control in Chronic Cannabis Users

Ian H Harding1, Nadia Solowij2,3, Ben J Harrison1, Michael Takagi1, Valentina Lorenzetti1, Dan I Lubman4, Marc L Seal5,6, Christos Pantelis1 and Murat Yücel1

1Department of Psychiatry, Melbourne Neuropsychiatry Centre, University of Melbourne and Melbourne Health, Melbourne, VIC, Australia

2School of Psychology, University of Wollongong, Wollongong, NSW, Australia

3Schizophrenia Research Institute, Sydney, NSW, Australia

4Turning Point Alcohol and Drug Centre, Eastern Health and Monash University, Melbourne, VIC, Australia

5Murdoch Childrens Research Institute, Melbourne, VIC, Australia

6Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia

Correspondence: Dr IH Harding and Professor M Yücel, Department of Psychiatry, Melbourne Neuropsychiatry Centre, Alan Gilbert Building, University of Melbourne, 3/161 Barry Street, Carlton, Melbourne, VIC 3053, Australia, Tel: (+61 3) 8344 1861, Fax: (+61 3) 9348 0469, E-mail: and

Received 21 September 2011; Revised 13 February 2012; Accepted 1 March 2012

Advance online publication 25 April 2012

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The long-term effect of regular cannabis use on brain function underlying cognitive control remains equivocal. Cognitive control abilities are thought to have a major role in everyday functioning, and their dysfunction has been implicated in the maintenance of maladaptive drug-taking patterns. In this study, the Multi-Source Interference Task was employed alongside functional magnetic resonance imaging and psychophysiological interaction methods to investigate functional interactions between brain regions underlying cognitive control. Current cannabis users with a history of greater than 10 years of daily or near-daily cannabis smoking (n=21) were compared with age, gender, and IQ-matched non-using controls (n=21). No differences in behavioral performance or magnitude of task-related brain activations were evident between the groups. However, greater connectivity between the prefrontal cortex and the occipitoparietal cortex was evident in cannabis users, as compared with controls, as cognitive control demands increased. The magnitude of this connectivity was positively associated with age of onset and lifetime exposure to cannabis. These findings suggest that brain regions responsible for coordinating behavioral control have an increased influence on the direction and switching of attention in cannabis users, and that these changes may have a compensatory role in mitigating cannabis-related impairments in cognitive control or perceptual processes.


attention; brain; cannabis; cognitive control; functional connectivity

via Neuropsychopharmacology - Abstract of article: Functional Connectivity in Brain Networks Underlying Cognitive Control in Chronic Cannabis Users.