Accidents & Violence, Author Interviews, Cannabis, Columbia, Opiods / 17.09.2016

MedicalResearch.com Interview with: June H. Kim Doctoral candidate,Department of Epidemiology Mailman School Public Health Columbia University MedicalResearch.com: What is the background for this study? What are the main findings? Response: A previous study indicated that states with medical marijuana laws had a reduced rate of opioid overdoses. If this is true, we'd expect to see similar reductions in opioid use associated with these laws. For this study, we used data from the FARS, a national surveillance system that records any crash events on US public roads that result in a fatality. Some states provide uniform testing of the majority of their deceased drivers, year to year. Among these states, we found that there was a lower prevalence of positive opioid toxicology tests among drivers crashing in states with an operational medical marijuana versus drivers crashing in states before a future medical marijuana law is implemented, particularly among drivers aged 21-40. (more…)
Author Interviews, Cannabis, Lancet, NIH / 06.09.2016

MedicalResearch.com Interview with: Dr. Wilson Compton MD, Deputy Director National Institute on Drug Abuse MedicalResearch.com: What is the background for this study? What are the main findings? Response: The study found that overall past year marijuana use by adults in the U.S. increased by more than 30% in the past dozen years, and 10 million more people were using marijuana in 2014 than in 2002. Use of marijuana on a daily (or near daily) basis increased even more markedly. In 2002, 3.9 million adults in the U.S. reported using marijuana daily or nearly every day, and the number more than doubled to 8.4 million by 2014. Along with this increase in use, we found that U.S. adults perceptions of the potential harms from using marijuana greatly decreased. Despite scientific evidence of potential harms, adults are much less convinced about dangers associated with using marijuana. These reductions in perceived harm were strongly associated with the increases in use. (more…)
AHA Journals, Author Interviews, Cannabis, Pulmonary Disease, UCSF / 27.07.2016

MedicalResearch.com Interview with: Matthew L. Springer, Ph.D. Professor of Medicine Division of Cardiology University of California, San Francisco San Francisco, CA MedicalResearch.com: What is the background for this study? Response: We've known for many years that secondhand smoke from tobacco cigarettes is harmful, and the vast majority of deaths thought to result from secondhand smoke are from cardiovascular disease. However, very little has been known about cardiovascular consequences of exposure to secondhand smoke from marijuana, and people tend to mistake the lack of evidence that it is harmful, for evidence that is it not harmful. As a result, many people seem relatively unconcerned about smoking marijuana and being exposed (or exposing others) to marijuana secondhand smoke. Politicians and policy makers also seem less willing to limit where people can smoke marijuana (under legal circumstances) than tobacco. What has been lacking is research into how exposure to marijuana smoke affects cardiovascular health. It has been difficult to do such experiments because marijuana is illegal in the eyes of the federal government. However, we have been studying the harmful effects of secondhand tobacco smoke on the function of rat blood vessels, which is similar to its harmful effects on human blood vessels, and we now have studied how the function of rat blood vessels is affected by exposure to secondhand marijuana smoke. (more…)
Author Interviews, Cannabis, JAMA, Pediatrics / 25.07.2016

MedicalResearch.com Interview with: George Sam Wang MD FAAP Assistant Professor of Pediatrics Section of Emergency Medicine, Medical Toxicology Department of Pediatrics University of Colorado Anschutz Medical Campus Children's Hospital Colorado MedicalResearch.com: What is the background for this study? Response: Many states have allowed medical and now recreational marijuana. The impact on pediatric population has not been fully described. MedicalResearch.com: What are the main findings? Response: Unintentional exposures presenting to our children's hospital and calls to our regional poison center significantly increased after our state allowed recreational marijuana. MedicalResearch.com: What should readers take away from your report? Response: Exposures in children are increasing in our state that allows medical and recreational Marijuana, many were edible products. Marijuana products should be treated like medications and household products in home and properly and safely stored. States looking to legalize marijuana need to consider safety rules and regulations during rule making processes. (more…)
Author Interviews, Cannabis, JAMA, Mental Health Research / 06.07.2016

MedicalResearch.com Interview with: Mary P. Heitzeg, PhD Assistant Professor Department of Psychiatry University of Michigan MedicalResearch.com: What is the background for this study? What are the main findings? Response: We wanted to find out if marijuana use changed the way the brain’s reward system responded to natural rewards. To probe response to natural reward, we used the chance to win some money and we observed brain response using functional magnetic resonance imaging (fMRI). We looked at brain activity when participants were 20 years old on average, and then again 2 years later and 4 years later. We found that over time marijuana use was associated with a decrease in the brain’s reward response to the chance to win money. This finding is consistent with current theories of addiction that suggest that repeated use of a substance may dampen the brain’s reward response to things normally perceived as pleasurable and this alteration may drive the individual to continue substance use. (more…)
Author Interviews, Cannabis, Columbia, JAMA / 21.10.2015

Deborah S. Hasin, Ph.D. Professor of Epidemiology Columbia University New York, New York 10032MedicalResearch.com Interview with: Deborah S. Hasin, Ph.D. Professor of Epidemiology Columbia University New York, New York 10032 Medical Research: What is the background for this study? What are the main findings? Dr. Hasin: This study is based on data from two large-scale national surveys conducted over an eleven-year period that are designed to provide information on many health-related conditions in U.S. adults, including use of marijuana and other substances, changes over time in the prevalence of marijuana users, changes over time in the prevalence of disorders such as marijuana abuse and dependence, and the correlates and predictors of those disorders. The main findings of the study are that between 2001-2002 and 2012-2013, the prevalence of marijuana users in the United States adult general population more than doubled, from 4.1% to 9.5%, while the prevalence of adults with marijuana use disorder (abuse or dependence) also increased substantially, from 1.5% to 2.9% of American adults. About three in ten adult marijuana users met criteria for a marijuana use disorder. The findings are consistent with other studies showing increases in rates of marijuana-related harms over the same general time period. This may be to do with how accessible marijuana has become, for example you can even find a purple lotus menu on various websites. This is perfectly safe and fun, but can develop into an addiction later in life. (more…)
Author Interviews, Cannabis, CDC, Pediatrics, Tobacco Research / 16.10.2015

MedicalResearch.com Interview with: Dr. Italia V. Rolle, PhD and Dr. Tim McAfee, MD Office on Smoking and Health National Center for Chronic Disease Prevention and Health Promotion CDC Medical Research: What is the background for this study? What are the main findings? Response: Since 2010, the proportion of U.S. 12th grade students who used marijuana during the preceding 30 days (21.4%) has surpassed the proportion who used cigarettes (19.2%). Negative outcomes associated with cigarette and marijuana use include addiction to one or both substances and diminished cognitive function, which can lead to lower academic achievement. CDC analyzed data from the 1997–2013 national Youth Risk Behavior Surveys (YRBS) among U.S. non-Hispanic white (white), non-Hispanic black (black), and Hispanic students in grades 9–12 to examine trends in the prevalence of current 1) exclusive cigarette or cigar use, 2) exclusive marijuana use, and 3) any use of the three products. CDC further examined the prevalence of current marijuana use among current users of cigarettes or cigars. During 1997–2013, exclusive cigarette or cigar use declined overall by 64%, from 20.5% to 7.4% (p<0.01). However, exclusive marijuana use more than doubled overall from 4.2% to 10.2% (p<0.01). Any cigarette, cigar, or marijuana use decreased overall from 46.1% to 29.9% (p<0.01), whereas marijuana use among cigarette or cigar users increased from 51.2% to 62.4%. Considerable increases were identified among black and Hispanic students toward the end of the study period for exclusive marijuana use and marijuana use among cigarette or cigar users. Increased exclusive marijuana use and use of marijuana among cigarette or cigar users could undermine success in reducing tobacco use among youths. (more…)
Author Interviews, Cannabis, Gender Differences, Pediatrics / 16.09.2015

MedicalResearch.com Interview with:Renee M. Johnson, PhD, MPH Assistant Professor Johns Hopkins Bloomberg School of Public Health, Dept. of Mental Health Deputy Director, Drug Dependence Epidemiology Training Program (DDET) Baltimore MD Renee M. Johnson, PhD, MPH Assistant Professor Johns Hopkins Bloomberg School of Public Health, Dept. of Mental Health Deputy Director, Drug Dependence Epidemiology Training Program (DDET) Baltimore MD Medical Research: What is the background for this study? What are the main findings? Dr. Johnson: There has been a lot of policy change with regard to marijuana. Several states have enacted laws regarding medical marijuana and decriminalization, and now four states and the District of Columbia have legalized use for adults. Along with these policy changes, there’s been concern that adolescent marijuana use would skyrocket. This prompted me to think about what’s happened over the past 15 years, and so I decided to examine past 15-year trends in adolescent marijuana use among US high school students. Our research team analyzed data from the Centers for Disease Control and Prevention’s Youth Risk Behavior Surveillance Study, or YRBS. It is a nationally-representative survey of high school students. A lot of the information we have about adolescents’ risk behavior comes from the YRBS. What we found is that marijuana use among US high school students has gone down over the time period. In 1999, 47% of high school students reported lifetime use of marijuana. By 2013, 41% reported lifetime use. Use was lowest in 2009, with 37% of high school students reporting lifetime use. The increase in use from 2009 to 2013 was not statistically significant, so we aren’t sure whether it represents random fluctuation or whether it indicates a reversal in trend. We also found that gender differences have gotten smaller over the time period, reflecting a real change. Boys have historically had higher rates of use, but that’s changing. In 1999, 51% of boys and 43% of girls reported lifetime marijuana use. By 2013, 42% of boys and 39% of girls reported lifetime use. (more…)
Author Interviews, Cannabis, Diabetes, Diabetologia, Heart Disease / 14.09.2015

Mike Bancks, MPH NHLBI Cardiovascular Disease Epidemiology & Prevention Pre-doctoral Fellow University of Minnesota School of Public HealthMedicalResearch.com Interview with: Mike Bancks, MPH NHLBI Cardiovascular Disease Epidemiology & Prevention Pre-doctoral Fellow University of Minnesota School of Public Health [email protected] Medical Research: What is the background for this study? What are the main findings? Response: We chose to research this topic because marijuana is the most commonly used illicit drug in the United States and use can be expected to increase as the effort to legalize marijuana for recreational and medicinal use grows. We found that individuals who reported using marijuana in excess of 100 times during young adulthood had 40% greater risk for developing prediabetes by middle adulthood. However, we did not find an association between marijuana use and overt diabetes during this same period in adulthood, suggesting that marijuana use may be a risk factor for the early stage of diabetes. (more…)
Author Interviews, Cannabis, Smoking, University Texas / 20.08.2015

Francesca M. Filbey PhD School of Behavioral and Brain Sciences Center for Brain Health University of Texas at Dallas Dallas, TXMedicalResearch.com Interview with: Francesca M. Filbey PhD School of Behavioral and Brain Sciences Center for Brain Health University of Texas at Dallas Dallas, TX Medical Research: What is the background for this study? What are the main findings? Dr. Filbey: Most studies exclude tobacco users from participating, but 70% of marijuana users also use tobacco. We were interested in investigating the combined effects of marijuana and tobacco. Our research targeted the hippocampus because smaller hippocampal size is associated with marijuana use. We chose to study short term memory because the hippocampus is an area of the brain associated with memory and learning. The main finding was surprising. The smaller the hippocampus in the marijuana plus nicotine user, the greater the memory performance. We expected the opposite, which was true of the non-using control group. (more…)
Author Interviews, Cannabis, CDC / 19.08.2015

Gillian Schauer, PhD, MPH Lead author and Contractor CDC’s Office on Smoking and HealthMedicalResearch.com Interview with: Gillian Schauer, PhD, MPH Lead author and Contractor CDC’s Office on Smoking and Health Medical Research: What is the background for this study? What are the main findings? Dr. Schauer: Marijuana is the most commonly used federally illicit drug in the United States. State-level policy change legalizing marijuana or one of its constituents for recreational or medical use is increasing. Currently, 23 states and DC have legalized medical use of marijuana. Four states (Alaska, Colorado, Oregon and Washington) and the District of Columbia have legalized recreational and medical use of marijuana.
  • This paper helps fill two important knowledge gaps. It describes how US adults are using marijuana—for example, whether they smoke it, eat it, or use it in a vaporizer—and it describes whether they report using it for medical reasons or for recreational reasons, or both. Data come from the 2014 Summer Styles national consumer online panel survey (sample size of 4,269 adults), and have been published in the American Journal of Preventive Medicine.
  • Nationally, marijuana is primarily consumed in combusted (smoked) form. In 2014, among adults who used marijuana in the past 30 days, 92.1% of adults said they smoked it, 16.1% ate or drank it, and 7.6% used a vaporizer or other electronic device.
  • Among adults who used marijuana in the past 30 days, 10.5% say they used it only for medical reasons, 53.4% used it only for recreational reasons, and 36.1% used it for both.
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Author Interviews, Cannabis, Heart Disease / 12.08.2015

MedicalResearch.com Interview with: Bradley C. Clark, MD Pediatric Cardiology Fellow – 3rd Year Division of Cardiology Children's National Health System Washington, DC 20010 Medical Research: What is the background for this study? What are the main findings? Dr. Clark: After consulting on multiple pediatric emergency room patients with K2 (synthetic cannabinoid) ingestion and electrocardiogram (ECG) abnormalities, my co-authors and I decided that it was worth taking a more detailed look at the potential cardiac effects of synthetic cannabinoids. We did a retrospective chart review and discovered a total of 8 patients in a 3 year period (2011 – 2014) at our institution with reported synthetic cannabinoid ingestion and concern for myocardial injury.  There were 3 individuals with evidence of ECG abnormalities in a segmental pattern with increased cardiac enzyme levels (troponins).  The other 5 individuals had ECG abnormalities either without troponin elevations or were not specifically tested.  Each individual that had an echocardiogram performed had normal intracardiac anatomy with normal biventricular systolic function. Given the elevated troponin levels and ECG abnormalities, there was a suspicion for myocardial ischemia in this small subset of patients without meeting specific criteria for myocardial infarction.  Interestingly, these individuals had completely normal echocardiograms and had no other potential cause of myocardial ischemia discovered by history.  Additionally, these were all teenage pediatric patients with documented K2 exposure without evidence of exposure to illegal substances. K2 and other synthetic cannabinoids are known to cause analgesia and euphoria and can lead to a lack of symptomatology.  Therefore, individuals with synthetic cannabinoid ingestion may not complain of the prototypical cardiac symptoms (chest pain, shortness of breath, palpitations) and may not have the workup to diagnose potential myocardial ischemia. (more…)
Author Interviews, Cannabis, Columbia, Lancet / 18.06.2015

Deborah S. Hasin, Ph.D. Professor of Epidemiology Columbia University New York, New York 10032MedicalResearch.com Interview with: Deborah S. Hasin, Ph.D. Professor of Epidemiology Columbia University New York, New York 10032 MedicalResearch: What is the background for this study? What are the main findings? Dr. Hasin: The background for the study was the need to identify the causes of the marked increase in marijuana use among U.S. adolescents over the last several years, given that early adolescent marijuana use leads to a number of adverse health and psychosocial consequences, including cognitive decline, into adulthood. We had two main findings from the study:
  1. A comparison of the rates of adolescent marijuana use between states that ever passed a medical marijuana law and those that did not revealed that states with such laws had higher rates of teen marijuana use, regardless of when they passed the law; and
  2. When we compared the rates of teen marijuana use in these states before and after passage of the laws, we did not find a post-passage increase in the rates of teen marijuana use. This suggests that some common factor may be causing both the laws to be passed and the teens to be more likely to smoke marijuana in the states that passed these laws.
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Author Interviews, Cannabis, Pediatrics / 15.06.2015

Dr. Gary Smith MD, DrPH Center for Injury Research and Policy Nationwide Children's Hospital Columbus, OhioMedicalResearch.com Interview with: Dr. Gary Smith MD, DrPH Center for Injury Research and Policy Nationwide Children's Hospital Columbus, Ohio Medical Research: What is the background for this study? What are the main findings? Dr. Smith: As of January 2015, 23 states and Washington D.C. have legalized marijuana for medical use. Four of those same states and Washington D.C. have also voted to legalize marijuana for recreational use. The debate about legalization often focuses on health effects among adults, economic benefits, and crime rates. Lost in the discussion is the potential harm to young children from unintentional exposure to marijuana. The study found that the rate of marijuana exposure among children 5 years of age and younger rose 147.5 percent from 2006 through 2013 across the United States. The rate increased almost 610 percent during the same period in states that legalized marijuana for medical use before 2000. In states that legalized marijuana from 2000 through 2013, the rate increased almost 16 percent per year after legalization, with a particular jump in the year that marijuana was legalized. Even states that had not legalized marijuana by 2013 saw a rise of 63 percent in the rate of marijuana exposures among young children from 2000 through 2013. Most children were exposed when they swallowed marijuana – that may be related to the popularity of marijuana brownies, cookies and other foods. (more…)
Cannabis, Heart Disease / 17.11.2014

Matthew L. Springer, Ph.D. Associate Professor of Medicine Division of Cardiology Cardiovascular Research Institute Broad Center of Regeneration Medicine and Stem Cell Research Center for Tobacco Control Research & Education Helen Diller Family Comprehensive Cancer Center University of California, San Francisco MedicalResearch.com Interview with: Matthew L. Springer, Ph.D. Associate Professor of Medicine Division of Cardiology Cardiovascular Research Institute Broad Center of Regeneration Medicine and Stem Cell Research Center for Tobacco Control Research & Education Helen Diller Family Comprehensive Cancer Center University of California, San Francisco     Medical Research: What is the background for this study? What are the main findings? Dr. Springer: The general public is aware that cigarette secondhand smoke is harmful. However, many people who actively avoid tobacco secondhand smoke don't feel the need to avoid marijuana secondhand smoke; they don't consider it harmful because there's no nicotine and because we who tell them to avoid tobacco smoke don't tell them to avoid marijuana smoke.  However, secondhand smoke from tobacco and marijuana is very similar in chemical composition (4000-7000 chemicals depending on whom you ask), aside from the nicotine and the THC (the psychoactive drug in marijuana). We and others have shown that brief exposure to tobacco secondhand smoke, such as 30 minutes, at real-world levels impairs vascular function in humans.  We developed a way to study vascular function (measured as arterial flow-mediated dilation; FMD) in living rats, and recently published that even one minute of sidestream smoke from the burning tips of tobacco cigarettes, a well-accepted model for secondhand smoke, is enough to start detecting impairment of FMD.  The main findings of the current study are that in laboratory rats, FMD was substantially impaired by a 30 minute exposure to marijuana secondhand smoke, when measured 10 minutes after the end of exposure.  Impairment was comparable to that resulting from exposure to tobacco sidestream smoke, although whereas impairment from tobacco smoke was temporary and had normalized by 40 minutes later, FMD was still impaired 40 minutes after the end of exposure to marijuana smoke.  Smoke from marijuana lacking THC still impaired FMD, showing that  (more…)
Author Interviews, Cannabis, Surgical Research / 03.10.2014

David Plurad, MD Los Angeles Biomedical Research In MedicalResearch.com Interview with: David Plurad, MD Los Angeles Biomedical Research Institute. Medical Research: What are the main findings of the study? Based on a survey of patients with traumatic brain injuries, a group of Los Angeles Biomedical Research Institute researchers found those who tested positive for tetrahydrocannabinol (THC), the active ingredient in marijuana, were more likely to survive than those who tested negative for the illicit substance. We surveyed 446 patients who were admitted to a major urban hospital with traumatic brain injuries between Jan. 1, 2010, and Dec. 31, 2012, who were also tested for the presence of THC in their urine. We found 82 of the patients had THC in their system. Of those, 2.4% died. Of the remaining patients who didn't have THC in their system, 11.5% died. While most - but not all - the deaths in the study can be attributed to the traumatic brain injury itself, it appears that both groups were similarly injured. The similarities in the injuries between the two groups led to the conclusion that testing positive for THC in the system is associated with a decreased mortality in adult patients who have sustained traumatic brain injuries. (more…)
Author Interviews, Cannabis, Lancet / 10.09.2014

MedicalResearch.com Interview with: Edmund Silins PhD, Research Fellow National Drug and Alcohol Research Centre UNSW Medicine University of New South Wales Sydney  Australia Medical Research: What are the main findings of the study? Dr. Silins: There were three particularly interesting aspects to the findings.
  • Firstly, we found clear and consistent associations between adolescent cannabis use and the young adult outcomes investigated.
  • Secondly, there was evidence of a dose-response effect such that the more frequently adolescents used cannabis the more likely they were to experience harms later in life.
  • Thirdly, for most outcomes, these associations remained even after taking into account a wide range of other factors which might potentially explain them.
The adverse effects were greatest for daily cannabis users. Specifically, adolescents who were daily cannabis users were, by the age of 25, more than 60% less likely to complete high school or obtain a university degree, seven times more likely to have attempted suicide, 18 times more likely to have been cannabis dependent, and eight times more likely to have used other illicit drugs, than adolescents who had never used the drug. (more…)
Addiction, Author Interviews, JAMA, Pediatrics / 29.07.2014

Sharon Levy, M.D., M.P.H. Director, Adolescent Substance Abuse Program Assistant Professor in Pediatrics Boston Children’s HospitaMedicalResearch.com Interview with: Sharon Levy, M.D., M.P.H. Director, Adolescent Substance Abuse Program Assistant Professor in Pediatrics Boston Children’s Hospital   Medical Research: What are the main findings of the study? Dr. Levy: We found that questions that asked about the frequency of alcohol, tobacco and drug use accurately triaged adolescents into "risk categories".  In other words, kids who reported using alcohol or marijuana "once or twice" last year were unlikely to have a substance use disorder, those who reported "monthly" use were very likely to meet diagnostic criteria for a "mild" or "moderate" substance use disorder while those who reported use weekly or more were very likely to meet diagnostic criteria for a "severe" substance use disorder. (more…)
Cannabis, Neurology, Stroke / 09.05.2014

MedicalResearch.com Interview with: Tara Dutta M.D. Vascular Neurology Fellow University of Maryland Medical Center MedicalResearch: What are the main findings of the study? Dr. Dutta: We analyzed data from the Stroke Prevention in Young Adults Study in order to evaluate for an association between self-reported marijuana use and ischemic stroke.   1,101 cases and 1,154 age, gender, and race-matched controls, aged 15-49 years old, were recruited from the greater Baltimore-Washington area between 1992 and 2008. Interviews were conducted to assess for various potential stroke risk factors, including illicit drug, alcohol, and tobacco use. Individuals reporting use of vasoactive illicit drugs, including cocaine and amphetamines, were excluded, yielding 751 cases and 813 controls. Logistic regression analysis was used to determine the association between marijuana use and ischemic stroke, adjusting for age, gender, race, current tobacco use, current alcohol use, hypertension, and diabetes. We did not find a positive association between marijuana use and ischemic stroke risk in our population of young-onset stroke patients compared to matched controls, even after controlling for current tobacco and alcohol use, hypertension, and diabetes.   A statistically significant inverse relationship was observed between remote use (defined as any use over one year ago) and stroke risk (adjusted OR 0.77, CI 0.61-0.98, p = 0.03). We also looked to see whether recent use (in the past 30 days), and particularly recent heavy use, was associated with ischemic stroke risk as has been suggested in the medical literature. Though our data did not show this association, the number of patients reporting recent use in our study was very small­­­­­­­. (more…)
Addiction, Author Interviews, Cannabis, Stroke / 22.11.2013

W. Scott Burgin, MD Professor and Chief Cerebrovascular Division Director, Comprehensive Stroke Center Department of Neurology USF College of Medicine Tampa General Hospital Stroke CenterMedicalResearch.com Interview with: W. Scott Burgin, MD Professor and Chief, Cerebrovascular Division Director, Comprehensive Stroke Center Department of Neurology USF College of Medicine Tampa General Hospital Stroke Center. MedicalResearch.com What are the main findings of the study? Dr. Burgin: Two cases of stroke, of embolic appearance, shortly after smoking synthetic marijuana. (more…)
Author Interviews, Hepatitis - Liver Disease, HIV, McGill / 16.08.2013

Marina Klein, MD, MSc, FRCP(C) Associate Professor of Medicine McGill University Health Centre Division of Infectious Diseases and Chronic Viral Illness Service 3650 Saint Urbain Montreal, Quebec H2X 2P4MedicalResearch.com Interview with: Marina Klein, MD, MSc, FRCP(C) Associate Professor of Medicine McGill University Health Centre Division of Infectious Diseases and Chronic Viral Illness Service 3650 Saint Urbain Montreal, Quebec H2X 2P4 Disease in HIV–Hepatitis C Coinfection: A Longitudinal Cohort Analysis                MedicalResearch.com: What are the main findings of the study? Dr. Klein: We showed that people with HIV and hepatitis C infection who smoked marijuana did not tend to progress more rapidly to liver fibrosis, liver cirrhosis or end-stage liver disease, even with increasing numbers of joints smoked per week. Previous studies that reported that marijuana was harmful to the liver were likely biased because they did not ensure that marijuana smoking occurred before the development of liver problems. (more…)