Loading

brain

  • by Paul Armentano, NORML Deputy Director August 3, 2017

    Marijuana researchCannabis use by teens is not independently linked with adverse changes in intelligence quotient or executive functioning, according to longitudinal data published online ahead of print in the journal Addiction.

    A team of investigators from the United States and the United Kingdom evaluated whether marijuana use is directly associated with changes over time in neuropsychological performance in a nationally representative cohort of adolescent twins. Authors reported that “family background factors,” but not the use of cannabis negatively impacted adolescents’ cognitive performance.

    They wrote: “[W]e found that youth who used cannabis … had lower IQ at age 18, but there was little evidence that cannabis use was associated with IQ decline from age 12 to 18. Moreover, although cannabis use was associated with lower IQ and poorer executive functions at age 18, these associations were generally not apparent within pairs of twins from the same family, suggesting that family background factors explain why adolescents who use cannabis perform worse on IQ and executive function tests.”

    Investigators concluded, “Short-term cannabis use in adolescence does not appear to cause IQ decline or impair executive functions, even when cannabis use reaches the level of dependence.”

    Their findings are consistent with those of several other studies – including those here, here, here, and here – finding that cannabis use alone during adolescence does not appear to have a significant, direct adverse effect on intelligence quotient.

    widely publicized and still often cited New Zealand study published in 2012 in The Proceedings of the National Academy of Sciences reported that the persistent use of cannabis from adolescence to adulthood was associated with slightly lower IQ by age 38. However, a follow up review of the data published later in the same journal suggested that the observed changes were likely due to socioeconomic differences, not the subjects’ use of cannabis. A later study by the initial paper’s lead investigator further reported that the effects of persistent adolescent cannabis use on academic performance are “non-significant after controlling for persistent alcohol and tobacco use.”

  • by Paul Armentano, NORML Deputy Director July 11, 2017

    marijuana_seedlingAlcohol consumption is associated with negative changes in gray matter volume and in white matter integrity, while cannabis use is not, according to data published online ahead of print in the journal Addiction.

    Investigators from the University of Colorado, Boulder and the Oregon Health & Science University evaluated neuroimaging data among adults (ages 18 to 55) and adolescents (ages 14 to 18). Authors identified an association between alcohol use and negative changes in brain structure, but identified no such association with cannabis.

    “Alcohol use severity is associated with widespread lower gray matter volume and white matter integrity in adults, and with lower gray matter volume in adolescents,” they concluded. By contrast, “No associations were observed between structural measures and past 30-day cannabis use in adults or adolescents.”

    Researchers acknowledged that their findings were similar to those of prior studies “suggesting that regionally specific differences between cannabis users and non-users are often inconsistent across studies and that some of the observed associations may actually be related to comorbid alcohol use.”

    A 2015 brain imaging study published in The Journal of Neuroscience similarly reported that cannabis use was not positively associated with adverse changes in the brain, but that alcohol “has been unequivocally associated with deleterious effects on brain morphology and cognition in both adults and adolescents.”

    Longitudinal data published in June in the British Medical Journal reported, “Alcohol consumption, even at moderate levels, is associated with adverse brain outcomes including hippocampal atrophy.”

    An abstract of the study, “Structural Neuroimaging Correlates of Alcohol and Cannabis Use in Adolescents and Adults,” appears online here.

  • by Paul Armentano, NORML Deputy Director April 27, 2017

    Cannabis PenaltiesA recently released white paper published by the National District Attorneys Association is calling for the federal government to strictly enforce anti-cannabis laws in states that have regulated its production and distribution for either medical or recreational purposes.

    The working group, which consists of D.A.s and prosecutors from more than a dozen states (including representatives from adult use states like California and Colorado), hopes to influence the Trump administration to set aside the 2013 Cole memorandum. That memorandum, authored by former US Deputy Attorney General James Cole, directs state prosecutors not to interfere with state legalization efforts and those licensed to engage in the plant’s production and sale, provided that such persons do not engage in marijuana sales to minors or divert the product to states that have not legalized its use, among other guidelines.

    “To maintain respect for the rule of law, it is essential that federal drug enforcement policy regarding the manufacture, importation, possession, use and distribution of marijuana be applied consistently across the nation,” the NDAA paper concludes.

    Predictably, authors repeat numerous falsehoods about marijuana and marijuana policy in an effort to bolster their call for a federal crackdown. Specifically, authors allege that cannabis damages the brain to a far greater extent than alcohol and that statewide regulations have increased young people’s access to the plant. Both claims are demonstrably false.

    The NDAA opines, “[Marijuana] is not like alcohol … because alcohol use does not cause the same type of permanent changes to teens’ ability to concentrate and learn.” Yet, well controlled studies dismiss the contention that cannabis exposure causes permanent structural damage to the brain.

    Specifically, a 2015 study assessed brain morphology in both daily adult and adolescent cannabis users compared to non-users, with a particular focus on whether any differences were identifiable in the nucleus accumbens, amygdala, hippocampus, and the cerebellum. Investigators reported “no statistically significant differences … between daily users and nonusers on volume or shape in the regions of interest” after researchers controlled for potentially confounding variables. In contrast to marijuana, researchers acknowledged that alcohol “has been unequivocally associated with deleterious effects on brain morphology and cognition in both adults and adolescents.”

    The NDAA further claims, “Legalization of marijuana for medical use and recreational use clearly sends a message to youth that marijuana is not dangerous and increases youth access to marijuana.”

    But data from the US Centers for Disease control reports that young people’s access to marijuana has fallen by 13 percent since 2002. The agency further reports, “Since 2002, the prevalence of marijuana use and initiation among U.S. youth has declined” – a finding that is consistent with numerous prior studies.

    Moreover, state-specific post-legalization data published in March by the Colorado Department of Public Health concludes: “[M]arijuana use, both among adults and among youth, does not appear to be increasing to date. No change was observed in past 30-day marijuana use among adults between 2014 (13.6 percent) and 2015 (13.4 percent). Similarly, there was no statistically significant change in 30-day or lifetime marijuana use among high school students between 2013 (lifetime: 36.9 percent, 30-day: 19.7 percent) and 2015 (lifetime: 38.0 percent, 30-day: 21.2 percent).” 2016 data compiled by Washington State Department of Social and Health Services similarly finds that “rates of teen marijuana use have remained steady” post legalization.

    The National District Attorneys Association is the largest and oldest prosecutor organization in the country. Their mission is to be “the voice of America’s prosecutors and strives to support their efforts to protect the rights and safety of the people in their communities.”

    The full text of the their paper, entitled “Marijuana Policy: The State and Local Prosecutors’ Perspective,” is available online here.

  • by Paul Armentano, NORML Deputy Director December 29, 2015

    2015: The Year In Review - NORML's Top 10 Events That Shaped Marijuana Policy

    NORML reviews the top news stories of 2015.

    #1 Congress Reauthorizes Medical Marijuana Protections
    Members of Congress approved language in the fiscal year 2016 omnibus spending bill that continues to limit the federal government from taking punitive action against state-licensed individuals or operations that are acting are in full compliance with the medical marijuana laws of their states. The provisions reauthorize Section 538 of the Continuing Appropriations Act of 2015, which states, "None of the funds made available in this act to the Department of Justice may be used … to prevent … states … from implementing their own state laws that authorize the use, distribution, possession, or cultivation of medical marijuana."

    #2 Federal Judge Upholds Marijuana’s Schedule I Status
    A federal judge in April rejected a motion challenging the constitutionality of cannabis’ classification as a Schedule I prohibited substance. "At some point in time, a court may decide this status to be unconstitutional," Judge Kimberly Mueller said from the bench. "But this is not the court and not the time." Judge Meuller had presided over five days of hearings in October 2014 in a challenge brought by members of the NORML Legal Committee.

    #3 Medical Cannabis Access Associated With Less Opioid Abuse
    States that permit qualified patients to access medical marijuana via dispensaries possess lower rates of opioid addiction and overdose deaths, according to a study published in July by the National Bureau of Economic Research, a non-partisan think-tank. The findings mirror those published in 2014 in The Journal of the American Medical Association concluding, "States with medical cannabis laws had a 24.8 percent lower mean annual opioid overdose mortality rate compared with states without medical cannabis laws."

    #4 DC Depenalizes Marijuana; Arrests Plummet
    Despite threats from members of Congress, District officials implemented voter-approved legislation earlier this year eliminating penalties associated with the possession and cultivation of personal use quantities of marijuana by adults. Following the law’s implementation, marijuana-related arrests in the nation’s capital fell 99 percent.

    #5 Marijuana Law Changes Don’t Change Youth Use, Attitudes
    Rates of youth marijuana use are unaffected by changing laws, according to data published in July in The American Journal of drug and Alcohol Abuse. Investigators evaluated trends in young people’s attitudes toward cannabis and their use of the substance during the years 2002 to 2013 – a time period where 14 states enacted laws legalizing the medical use of the plant, and two states approved its recreational use by adults. "Our results may suggest that recent changes in public policy, including the decriminalization, medicalization, and legalization of marijuana in cities and states across the country, have not resulted in more use or greater approval of marijuana use among younger adolescents," researchers reported.

    #6 Gallup Poll: More Americans Than Ever Say Marijuana Should Be Legal
    Fifty-eight percent of Americans believe that "the use of marijuana should be made legal," according to nationwide survey data released in October by Gallup pollsters. The percentage ties the highest level of support ever reported by Gallup, which has been measuring Americans’ attitudes toward cannabis since the late 1960s. The percentage is more than twice the level of support reported in the mid-1990s.

    #7 Study: Marijuana Use Not Associated With Changes In Brain Morphology
    Marijuana use is not associated with structural changes in the brain, according to imaging data published in January in The Journal of Neuroscience. Investigators assessed brain morphology in both daily adult and adolescent cannabis users compared to non-users. They found "no statistically significant differences … between daily users and nonusers on volume or shape in the regions of interest" after researchers controlled for participants’ use of alcohol. "[T]he 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," researchers reported.

    #8 Marijuana Consumers Less Likely To Be Obese, Suffer Diabetes Risk
    Those who consume cannabis are 50 percent less likely to suffer from metabolic syndrome as compared to those who do not, according to findings published in November in The American Journal of Medicine. Metabolic syndrome is a group of risk factors, including high blood pressure, high blood sugar, unhealthy cholesterol levels, and abdominal fat, which are linked to increased risk of heart disease and adult onset diabetes, among other serious health consequences. The findings are similar to those of previous studies reporting that those who use cannabis are less likely to be obese or suffer from diabetes.

    #9 NHTSA: THC-Positive Drivers Don’t Possesses Elevated Crash Risk
    Drivers who test positive for the presence of THC in their blood are no more likely to be involved in motor vehicle crashes than are drug-free drivers, according to a case-control study released in February by the United States National Highway Transportation and Safety Administration. Authors reported that drivers who tested positive for the presence of THC possessed an unadjusted, elevated risk of accident of 25 percent (Odds Ratio=1.25) compared to controls (drivers who tested negative for any drug or alcohol). However, this elevated risk became insignificant (OR=1.05) after investigators adjusted for demographic variables, such as the drivers’ age and gender. The study is the largest of its kind ever conducted in the United States.

    #10 Legal Marijuana States Collect Over $200 Million In New Tax Revenue
    Taxes on the legal production and sale of cannabis in the states of Colorado and Washington have yielded over $200 million in new revenue since going into effect in 2014, according to calculations reported by The Huffington Post in September. Colorado collected more than $117 million dollars from marijuana sales while Washington collected over $83 million. Cannabis sales commenced in Oregon in on October 1, 2015 and have yet to begin in Alaska.

  • by Paul Armentano, NORML Deputy Director August 26, 2015

    Latest JAMA Studies Largely Fail To Support Past Claims About Marijuana And Brain HealthTwo new studies published online today in JAMA (Journal of the American Medical Association) Psychiatry provide little support for previous claims that cannabis exposure is significantly harmful to the developing brain.

    The first study, which assessed the effects of cannabis exposure on brain volume in exposed and unexposed sibling pairs, reported that any identifiable differences “were attributable to common predispositional factors, genetic or environmental in origin.” By contrast, authors found “no evidence for the causal influence of cannabis exposure” on brain morphology.

    The trial is “the largest study to date examining the association between cannabis exposure (ever versus never used) and brain volumes.”

    The study is one of two recent clinical trials to be published in recent months rebutting the claims of a widely publicized 2014 paper which alleged that even casual marijuana exposure may be linked to brain abnormalities, particularly in the region of the brain known as the amygdala. In January, researchers writing in The Journal of Neuroscience reported “no statistically significant differences … between daily [marijuana] users and nonusers on [brain] volume or shape in the regions of interest” after researchers controlled for participants’ use of alcohol. Similarly, today’s JAMA study “casts considerable doubt on hypotheses that cannabis use … causes reductions in amygdala volumes.”

    A second study appearing today in the journal assessed whether cannabis use during adolescence is associated with brain changes that may be linked to an increased risk of schizophrenia. While researchers reported finding an association among male subjects who possessed a high genetic predisposition toward schizophrenia, authors reported that no such association existed among male subjects who were at low risk for the disease, or among females in either the high risk or low risk categories. The finding is consistent with the theory that early onset cannabis use may potentially exacerbate symptoms in a minority of subjects predisposed to the disease, but it contradicts claims that marijuana exposure is a likely cause of schizophrenia, particularly among those who are not already vulnerable to the disease.

    Abstracts of both new studies appear online in JAMA Psychiatry here and here.

Page 1 of 3123