Late last year, the press and marijuana-legalization opponents gave a lot of attention to a studysuggesting that daily marijuana use shrinks users' brains. New research indicates that claim and other reports of cannabis-caused changes to brain structure simply aren't true. The new study, "Daily Marijuana Use Is Not Associated with Brain Morphometric Measures in Adolescents or Adults," published in the latest edition of the Journal of Neuroscience, suggest that alcohol use was responsible for previous studies finding brain changes.

A six-year study of Britain's drug laws by leading scientists, police officers, academics and experts has concluded it is time to introduce decriminalisation. The report by the UK Drug Policy Commission (UKDPC), an independent advisory body, says possession of small amounts of controlled drugs should no longer be a criminal offence and concludes the move will not lead to a significant increase in use. (See also: Case for drug decriminalisation rests on failure of 40-year-old law)

Whether or not using cannabis can lead to cognitive impairment is a hot topic of research and public interest. Given the extensive media attention to findings that suggest detrimental effects of cannabis on cognition, brain function and mental health, you would be forgiven for thinking smoking a spliff was akin to repeatedly bashing yourself over the head with a giant bong. However, since much of the work to date is cross-sectional (that is, measurements are taken only at one time in a person’s life), we cannot know whether cannabis users would have performed any differently before they started using cannabis.

Does marijuana cause psychotic disorders such as schizophrenia, and do associated symptoms like paranoia lead to violent crimes? That’s what writer Alex Berenson is claiming. As part of his new book promotion, Berenson published a New York Times op-ed that also blames the drug for “sharp increases in murders and aggravated assaults” purportedly observed in some states that allow adult recreational marijuana use. As scientists with a combined 70-plus years of drug education and research on psychoactive substances, we find Berenson’s assertions to be misinformed and reckless.

Heavy marijuana use is associated with cognitive decline in about 5% of teens, according to a new study, which suggests that the heaviest users could lose 8 IQ points, according to a report, published in the Proceedings of the National Academy of Sciences.If the link is real, the effects on cognition could be dramatic. But intelligence and cognition is affected by a plethora of other factors, including genetic, social and environmental influences that may supersede any influence from drug use. 

In the United States and beyond, drug research ignores most people who use drugs. While the large majority of people who use drugs (PWUD) do not suffer from substance use disorders (anywhere from 80-90 percent), research in the field predominantly focuses on the minority experience of harmful use. In part, this is an issue of the needs and urgency surrounding severe substance use disorders. At the same time, it is also an issue of funding. The National Institute of Drug Abuse (NIDA), which funds around 80 percent of all drug research around the world, has the stated goal of funding research on “drug abuse and addiction.” The question of what drug research is “fundable” and/or “publishable” in this context incentivizes researchers to continue to do more research on the harms of drugs.

The UK's drug laws are preventing scientists from carrying out vital research to unlock our understanding of the brain and find new treatments for conditions such as depression and Parkinson's disease, according to Professor David Nutt, a leading neuroscientist and former government drug adviser. "Things are actually getting worse," said Nutt, referring to the restrictions placed on research.

Most drug research focuses on the harms they cause, but studying the pleasure they provide will improve our understanding of why people use them. Among other things, this knowledge could be used to help people who develop drug problems, such as dependency. These people have often experienced significant trauma in their lives and use drugs to self-medicate. If we knew more about how this self-medication worked, we could radically transform our approach to treatment. By concentrating research funding on problems people develop rather than investigating motives and benefits of drug use, research has contributed to a distorted view of drugs and the people that use them.

Cannabis is the cutting-edge drug for reform, the only politically plausible candidate for major legal change, at least decriminalisation (removal of criminal penalties for possession) and perhaps even outright legalisation (permitting production and sale). Compared with other drugs, the harms, physiological or behavioural, are less severe and the drug is better integrated into the culture. Throughout Western Europe and in the Antipodes there is pressure for reductions in the punitiveness of the marijuana regime.

Download the paper (PDF)

Cannabis is the cutting-edge drug for reform, the only politically plausible candidate for major legal change, at least decriminalisation (removal of criminal penalties for possession) and perhaps even outright legalisation (permitting production and sale). Compared with other drugs, the harms, physiological or behavioural, are less severe and the drug is better integrated into the culture. Throughout Western Europe and in the Antipodes there is pressure for reductions in the punitiveness of the marijuana regime.

Download the paper (PDF)

"The war on drugs has failed," said a recent report compiled by the Global Commission on Drug Policy, which comprised a former UN secretary-general, former presidents of Mexico, Colombia and Brazil, a former US Secretary of State and a host of public intellectuals, human rights activists and politicians.

A scientific committee convened by the French government has concluded that it might be “appropriate” to legalise cannabis for therapeutic use in a report. The committee, convened by France's ANSM (the French National Agency for the Safety of Medicines and Health Products), stated that it would be “appropriate to authorise the use of therapeutic cannabis […] in certain clinical situations and in cases where [existing] therapies provide insufficient relief or are not well tolerated”. According to the committee, the law should authorise the use of the plant in cases of severe pain, for certain types of epilepsy, as part of ancillary care for cancer patients, in certain “palliative situations” and for the muscular contractions linked to multiple sclerosis.

For three years, the Vancouver Area Network of Drug Users’ (VANDU) operated an unsanctioned, peer-run “safer smoking room” for crack users in a small ventilated washroom in its Downtown Eastside facility. It protected crack users from violence, connected them with health care services, kept them away from public spaces and prevented the spread of disease from pipe-sharing, according to the authors of a recently-published study titled “We need somewhere to smoke crack.”

Standard units for grading the potency of cannabis – similar to those already used for alcohol – would result in significant improvements in the mental health of users, according to addiction experts. Researchers from the Addiction and Mental Health Group at the University of Bath, working with staff from King’s College London, UCL and the Australian Catholic University in Melbourne, say more needs to be done to make people aware of the levels of THC – the main psychoactive component – in the cannabis they are consuming. Writing in the journal Addiction, the experts suggest a unit level should be set at 5mg of THC – the amount that would typically be found in a small joint. This is enough to induce intoxication but without psychotic symptoms. (See also: Making cannabis safer)

New research from Harvard Medical School, in a comparison between families with a history of schizophrenia and those without, finds little support for marijuana use as a cause of schizophrenia. “The results of the current study suggest that having an increased familial morbid risk for schizophrenia may be the underlying basis for schizophrenia in cannabis users and not cannabis use by itself,” note the researchers.

Research on substance use has taught me a major overarching lesson: we are much more likely to demonize drugs for their negative effects than consider their neutral or potentially positive impacts. Or – in scientific terms – there is a built-in bias in the scientific literature, textbooks, and the popular press towards highlighting the negative aspects of drug use. And more ink has been spilled about cannabis than any other drug, perhaps because it’s the most widely used illegal drug and the subject of intense debate concerning its regulation.

Frequent cannabis use and high-strength varieties are likely to increase the chance of mental health problems, according to researchers in Lancet Psychiatry. Experts have previously flagged a link between cannabis use and psychosis. Now research suggests the potency of the cannabis is important, with patterns in cannabis use linked to how often new cases of psychotic disorders arise. The study estimated that 30% of first-time cases of psychotic disorders in south London, and half of those in Amsterdam, could be avoided if high-potency cannabis was not available. The study had limitations because it relied on self-reported use of cannabis and a small numbers of participants. Also, THC and CBD content of the cannabis was not directly measured. (See also: NORML responds to latest cannabis and psychosis claims)

Almost all cannabis seized by police now comprises high-strength varieties, with outdoor-grown herbal strains and hashish barely found, according to a new analysis. In the first study of its kind for 10 years, researchers found 94% of samples seized were varieties with a high psychoactive content, suggesting they dominate the illicit market. The increasing discrepancy between THC and CBD levels in cannabis could increase the number of users at risk of developing psychotic disorders. "It’s certainly worth putting the real risk into context, which this doesn’t," said Jon Liebling of the United Patients Alliance (UPA). "The risk of early onset psychosis due to long-term heavy use of cannabis is one in 26,000." (See also: How hash and weed all but disappeared from Britain's streets, as high-strength ‘skunk’ took over)

K2 overdoses in Brooklyn sent 33 people to hospital. The rise of K2 could be fueled by a twist on the "gateway drug" theory: it’s not marijuana use, but marijuana criminalization, that could lead many to turn to synthetic cannabinoids. Just like marijuana activists are championing studies that suggest cannabis reforms could lead to decreased heroin and opioid use, stopping the spread of K2 could become a rallying point for the marijuana movement. As Adam Winstock, a consultant psychiatrist and founder of the Global Drug Survey put it, "In some regions, it could be the best argument for legalization in quite some time."

A recent neuroscience study from Harvard Medical School claims to have discovered brain differences between people who smoke marijuana and people who do not. Such well-intentioned and seemingly objective science is actually a new chapter in a politicized and bigoted history of drug science in the United States. Different-looking brains tell us literally nothing about who these people are, what their lives are like, why they do or do not use marijuana, or what effects marijuana has had on them.