Overtreatment of Diabetes in Elderly Patients Remains Underrecognized.

The primary goal of treatment for diabetes, as for many chronic conditions, is to lower rates of death and complications from the disease. But an equally important goal in medicine, one recognized over 2 millennia ago, is to “do no harm,” and sometimes this balance between help and harm can be difficult to accomplish.

In this week’s issue of JAMA, a theme issue on diabetes, a viewpoint discusses the overtreatment of diabetes in certain patient populations—that is, the overuse of blood sugar–lowering medications to the point at which average blood sugar levels may be too low and cause more harm than benefit. The authors refer back to a study published about 6 months ago in JAMA Internal Medicine, in which researchers looked at administrative data from a large population of Veterans Affairs patients and found surprisingly high rates of overtreatment.

The JAMA Internal Medicine study focused on patients with diabetes who were most susceptible to hypoglycemia (low blood sugar) caused by diabetes overtreatment, which included patients older than 75 years of age, those who had poor kidney function, and those who had a diagnosis of cognitive impairment or dementia. Overtreatment among these patients was defined as having a hemoglobin A1c (HbA1c) level (a measure of average blood sugar values over a 3-month period) that was less than 6.0% (roughly corresponding to a blood sugar of 126 mg/dL), less than 6.5% (blood sugar of 140 mg/dL), or less than 7.5% (blood sugar of 154 mg/dL).

The researchers found that rates of overtreatment were 10.1% for HbA1c less than 6.0%, 25.2% for HbA1c less than 6.5%, and 44.3% for HbA1c less than 7.0%. However, no information on actual rates of hypoglycemia or the complications thereof (such as emergency department visits or hospitalizations) was collected.

Author Patrick O’Malley, MD, MPH, discusses his views on the implications of this study with news@JAMA.

news@JAMA: The study showed that 44% of VA patients with diabetes and risk factors for serious hypoglycemia may be getting overtreated to some degree. In your article, you state that these results are “sobering.” Why do you think overtreatment happens so often?

Dr O’Malley: In general, overtreatment is a multifactorial issue related to the culture of care. In medicine, physicians always want to do something, to take something, such as a blood sugar value, from abnormal to normal. We rely on clinical evidence for these treatment goals, but sometimes, in the absence of good clinical evidence, we must instead rely on biologic plausibility, and extrapolate data from one population to another. This extrapolation often happens with the elderly, who are not included as participants in many clinical trials on which many general clinical guidelines and recommendations are based. That’s why overtreatment tends to happen in the elderly, not just for diabetes, but for other diseases as well.

Another issue is the use of quality metrics, or A1c in the case of diabetes, with the notion of “lower is better” driving this culture of aggressive care. The VA system in particular is very good at driving such quality metrics to success, which probably leads to higher rates of overtreatment. It’s basically a case of good intentions and good systems gone awry.

news@JAMA: It seems that since elderly individuals are underrepresented in several of the major diabetes trials, evidence on the benefits vs harms of intensive glucose control might be difficult to interpret, and the ideal A1c level for elderly people is still a mystery. Is there a bottom line that can be drawn from these studies?

Dr O’Malley: Yes, the bottom line is that for anyone who has a life expectancy greater than 15 years, an A1c goal of less than 7 is reasonable. For all other people, which includes elderly individuals as well as younger individuals with multiple comorbidities and lower life expectancies, an A1c goal of less than 7 might be more harmful than beneficial. Providers should be tailoring A1c goals to the individual, and life expectancy should be a major part of that equation.

news@JAMA: For individuals with a life expectancy of less than 15 years, what is a reasonable A1c goal? Is there an upper limit?

Dr O’Malley: There’s not a whole lot of great evidence to support a specific upper limit, but in general, a blood glucose consistently over 200 is where people start running into problems with immune system dysfunction and increased risk of infections. This corresponds to an A1c of about 9.

news@JAMA: What can doctors and hospital systems do to address the issue of overtreatment?

Dr O’Malley: On a systems level, we have to be smarter about choosing metrics, and smarter about individualizing metrics to individual patients—older patients should have different metrics than younger ones. On an individual physician level, we should strive to be less pharmacologically oriented, especially in the elderly. There is a lot that therapeutic lifestyle changes can achieve. We also tend to be overly aggressive with monitoring, ordering A1c tests too frequently, and telling our patients to check blood sugars four times a day. Checking blood sugars three times a week is plenty for most stable patients with diabetes.

news@JAMA: What about for patients who might be skeptical or resistant toward the idea of withdrawing or decreasing the intensity of care?

Dr O’Malley: It’s true that this might be a major barrier, as patients are sometimes reluctant to do this, or confused as to why the same doctor who told them to intensify their diabetes control is now telling them to scale back. This is why it’s so important to have a trusting and invested doctor-patient relationship.

Sometimes as doctors, in an effort to stay as up to date and proactive as possible, we change our culture toward treatment before the evidence is truly there, and this ends up harming patients, wasting resources, and engendering distrust among patients toward their physicians and the healthcare system as a whole. Another example of this is what happened with hormone replacement therapy for menopausal women back in the ’90s—we were so quick to act on the benefits of hormone replacement before the long-term evidence was available and then realized it was actually more harmful than beneficial.

Cannabis Lube Will Give You A Real Internal High

Don’t end your night high and dry.

Get the new cannabis oil-infused lube,Foria, for a sexual experience that will either give you “multiple orgasms over a 15-minute span,” or an insane craving for Taco Bell. We’re not sure, but Nerve reports that Foria’s vagina-safe concoction willactually get women high.

Foria uses a cannabis oil that contains THC and other cannabinoids, blended with coconut oil, for a “viscous, slippery, toy-safe” experience, according to Nerve. And it works! The site reports:

“The product works specifically for women because of the very sensitive and absorbent membrane of the vagina and entire vulva — inner and outer labia and clitoris included.”

That sounds great, but before you pull out your credit cards, there is a catch. Foria is only available to California residents who have a valid physician’s recommendation letter, according to the site. If you’re one of those lucky few, you can pick up a small bottle for about $88.

Testers’ reviews vary, but Foria founder Mathew Gerson claims it gives women “a sense of embodiment, a sense of dropping into a more full relationship to sexual sensations, and sensations around the body. As you can imagine, as that builds up to orgasm, if orgasm is a part of your experience, then that can lead to intensification and a more full body experience.”

We also know that all reactions to marijuana ingestion vary greatly — and there aren’t any FDA studies on taking products like these vaginally — so use with caution. Basically, if you don’t already smoke or ingest marijuana, cannabis lube probably shouldn’t be your first try in getting high.

The Science of Weight Loss.


New NHS statins guidance ‘risks harming patients’.

Telling millions of healthy people to take statins risks harming ‘many patients over many years’, doctors warn Jeremy Hunt, the Health Secretary, and watchdogs

Proposals to advise twelve million people to take statins could have “worrying” consequences because the plans were borne out of an “overdependence” on studies funded by the pharmaceutical industry

Proposals to advise twelve million people to take statins could have “worrying” consequences because the plans were borne out of an “overdependence” on studies funded by the pharmaceutical industry, doctors said Photo: Alamy.
 Millions of people over the age of 50 risk harming their health if they follow new NHS guidance telling them to take statins, leading doctors have warned the Health Secretary.

Proposals to advise 12 million people to take the drugs could have “worrying” consequences because the plans were borne out of an “overdependence” on studies funded by the pharmaceutical industry, they say.

The group cites research, independent of the drug industry, showing that statins have been associated with a 48 per cent increase in the risk of diabetes in middle-aged women. Other potential side effects could include depression, fatigue and erectile dysfunction, they warn.

In a letter to Jeremy Hunt, the prominent clinicians, including the head of the Royal College of Physicians and a former chairman of the Royal College of General Practitioners, say that the majority of the National Institute for Health and Care Excellence (Nice) panel responsible for drawing up the guidelines has “direct financial ties” to firms that manufacture statins.

They say that those with “industry conflicts” should be barred from helping to prepare drug guidelines.

Nice will publish its final recommendations next month, after a public consultation. In February it announced its plans to cut the “risk threshold” for statins in half — meaning that the vast majority of men aged over 50 and most women over the age of 60 are likely to be advised to take the drugs to guard against strokes and heart disease.

Experts said the changes would mean that the number of patients advised to take cholesterol-lowering drugs was likely to rise from seven million to 12 million, leaving one in four adults on the medication.

Nice says the guidance will prevent many people from becoming ill and dying prematurely.

By contrast, recent academic papers have questioned the widespread use of statins, claiming that they cause harmful side effects and do not cut death rates — although the authors of two such articles in the British Medical Journal have since withdrawn statements after some figures they cited were found to be incorrect.

In their letter to Mr Hunt and Nice, nine doctors and academics warn that the guidelines will result in the “medicalisation of five million healthy individuals”.

They call on Nice to shelve the proposals until independent experts have been allowed to examine the data on which they have been based.

“The potential consequences of not doing so are worrying: harm to many patients over many years, and the loss of public and professional faith in Nice as an independent assessor,” they write.

“Public interests need always to be put before other interests, particularly pharma.”

The doctors and academics highlight a series of concerns that they say should result in publication of the guidance being delayed.

Led by Sir Richard Thompson, the president of the Royal College of Physicians, they accuse Nice of relying on “hidden data” to reach its conclusions, arguing that crucial studies have not been open to scrutiny. Almost all the research was funded by pharmaceutical firms and should be “open to analysis by a third party with appropriate expertise”, they write.

The doctors, who also include Prof Clare Gerada, a former chairman of the Royal College of General Practitioners, and Prof David Haslam, the chairman of the National Obesity Forum, added that they were “seriously concerned” that eight members of the Guideline Development Group had “direct financial ties to the pharmaceutical companies that manufacture statins”.

The eight members highlighted by the signatories included Dr Anthony Wierzbicki, the chairman of the panel, who declared involvement in a number of commercial clinical trials of new cholesterol-lowering drugs.

The doctors also drew attention to Emma McGowan, a specialist heart nurse who held a post sponsored by AstraZeneca for a year and has been paid by Amgen, another firm, to work on studies.

Dr Dermot Neely, the head of the clinical biochemistry department at Newcastle University and another member of the panel, has received funding from Roche Pharma, Genzyme, Aegerion, Amgen and Sanofi for taking part in “one-off advisory boards”.

All of the links to pharmaceutical firms were declared to Nice at the time that the panel was preparing guidance. The watchdog said in each case the involvement was “judged not to be specific enough to warrant withdrawal”.

A spokesman for Nice said: “The conflicts of interest declared by committee members involved in producing this guideline have been managed appropriately. They have not influenced in any way the draft recommendations on the use of statins.”

Responding to the letter, Prof Mark Baker, the director of the centre for clinical practice at Nice, said: “The independent committee of experts found that if a patient and their doctor measure the risk and decide statins are the right choice, the evidence clearly shows there is no credible argument against their safety and clinical effectiveness.”

Is Kenya’s Vera Sidika a BleachedBeauty?

Skin lightening is under the spotlight in Kenya after a well-known socialite, Vera Sidika, revealed she has spent tens of thousands of dollars on the treatment – prompting the hashtag #BleachedBeauty.Two photos of Vera Sidika from her Instagram page where her skin looks light

Vera Sidika is sometimes dubbed “Kenya’s Kim Kardashian”, as – like Kardashian – she is famed for posting photos of her voluptuous backside on social media. But this time, it’s not her bottom that’s under scrutiny.

On Friday night she gave an interview on Kenyan TV in which she spoke openly about the skin lightening treatment she has recently undergone. “Looking good is my business,” she said matter-of-factly. “My body is my business, nobody else’s but mine.” Sidika said she’d had the skin lightening done in the UK and suggested it cost somewhere in the region of 15 million Kenyan shillings ($170,000; £100,000). She says she’s already seen an increase in demand for her services.

The response on Kenyan social media was huge. “I was accused of promoting or endorsing a white-centred view of beauty for African girls by interviewing her,” the host of the programme Larry Madowo told BBC Trending. “The criticism was quite intense.” NTV decided to run a follow-up programme to discuss skin lightening, and encouraged people to share their thoughts using #BleachedBeauty.

Two photos of Vera Sidika from her Instagram page a few months ago where her skin appears darker
These photos were posted some months ago and show a darker-looking Vera Sidika

More than 4,000 people have done so, and many of comments have been damning. “#BleachedBeauty is fake. Only those with low self-esteem would do that,” tweeted one. “#Bleachedbeauty Ladies will soon begin bleaching their brains so they come up with bright ideas,” tweetedanother. But others commenting on YouTube came to Sidika’s defence, praising her “openness and honesty” in speaking about the issue.

“Fascinating”, “astounding” and “hypocritical” is how TV host Larry Madowo describes the reaction on social media. Many men in Kenya do indeed prefer light-skinned women, he says – referring to them affectionately as “yellow, yellow”. Dark-skinned women are sometimes derogatively called “tinted”.

Various photos of Vera Sidika from her Instagram page
Vera Sidika works in the fashion business and is planning on opening a high-end hair salon

Unlike in India where lightening creams are very common, in Kenya, skin lightening remains quite hush-hush, and is generally done in small backstreet venues. Experts believe it’s on the rise, and warn of the dangers of unregulated black market treatments.

Skin lightening has been an issue in Africa for some time and came to the fore earlier this year when Nigerian-Cameroonian pop star Dencia launched a cream called Whitenicious.

Hubble space telescope spies teenage galaxies.

Ultraviolet images probe star formation 5 billion to 10 billion years ago

DEEP SPACE  Ten thousand galaxies fill a tiny patch of sky in a new image from the Hubble Space Telescope.  Ultraviolet light (blue) comes from star factories in galaxies that were active 5 to 10 billion years ago.

BOSTON — The distant universe just got a new dash of color. Ultraviolet images from the Hubble Space Telescope reveal star birth in galaxies that existed 5 billion to 10 billion years ago. The new images can help researchers reconstruct how galaxies grew to form the variety of shapes and sizes seen today.

There’s been a gap in astronomers’ understanding of galaxy growth, said Harry Teplitz on June 3 at the American Astronomical Society Meeting. The Caltech astrophysicist likened the gap to learning about people by watching only infants and college graduates. “We want to study galaxies in their teenage years,” he said.

The new images add ultraviolet data to the Hubble Ultra Deep Field, a well-studied region of the sky in the constellation Fornax. The region is one-tenth as wide as a full moon yet contains roughly 10,000 galaxies. Ultraviolet light lets astronomers see the youngest, hottest, most massive stars in distant galaxies and is the best tool researchers have for understanding star formation.

Hubble’s new images show stars forming in individual clumps spread throughout each galaxy. “We knew that was the case for galaxies today,” Teplitz said, “but no one had seen it in a teenage galaxy.”

Deadly bat disease gets easier to diagnose.

In less than a decade, the deadly bat disease called white-nose syndrome has taken hold across the eastern half of the United States and up into Canada. With the disease confirmed in Michigan and Wisconsin in April, WNS has now been documented in 25 U.S. states and five Canadian provinces. Millions of hibernating bats from six species have been infected with the fungus Pseudogymnoascus destructans, or Pd.little brown bat with white nose syndromeThe disease attacks a bat’s skin, and an infected bat often displays abnormal behavior, such as heading for the mouth of a cave in winter when it should be tucked away, safe and warm, far from the entrance. Such behavior is thought to be one reason behind infected bats’ loss of fat reserves, emaciation and death.

Since scientists discovered the epidemic, they’ve been struggling to figure out how to prevent its spread. One problem is diagnosis. The “gold standard” for diagnosing white-nose syndrome has been to euthanize a bat, then take samples of its skin and stick them under a microscope. But this is time-consuming, and it requires special facilities — and the death of the bat.


When seen under UV light, lesions caused by the fungus appear to fluoresce yellow-orange on this Indiana bat infected with white-nose syndrome.


However, researchers have just found a new tool for diagnosing WNS — ultraviolet light. Shining UV light with a wavelength between 368 and 385 nanometers causes thePd fungus to fluoresce orange-yellow, Gregory G. Turner of the Pennsylvania Game Commission and colleagues report May 22 in the Journal of Wildlife Diseases

Finding fungal infections with UV light is actually a tried and true technique, used to diagnose tinea capitis (also known as ringworm) in people, for example. Scientists aren’t sure whyPd lights up under UV light, but they think that once Pdfilaments, called hyphae, penetrate the bat’s skin, those hyphae secrete substances that eat away at the living tissue and also happen to fluoresce under UV light.

In the new study, the researchers first tested their idea on the wings of 168 bats that had been submitted to the U.S. Geological Survey National Wildlife Health Center from March 2009 to April 2012. Of those bats, 80 fluoresced under UV light, and 79 of 80 were confirmed to have WNS. All 88 bats that did not glow yellow-orange tested negative for the fungus.

The method got a test out in the field in 2012 in the Czech Republic, where WNS has been found but without the devastating mortality that has accompanied its spread in North America. Twenty-one of 22 bats that fluoresced tested positive for Pd in the lab; all 40 bats that didn’t have any orange-yellow spots under the UV light tested negative.

The UV light method won’t replace other tests for WNS syndrome, the researchers admit. It probably won’t detect a bat with a mild case of the disease, and an inexperienced observer (or one without great vision) may miss infected bats. But, they write, “the ability to perform targeted and nonlethal sampling of bats for WNS offers a needed tool to facilitate enhanced surveillance and research for the disease.” And that can only be a positive thing in the efforts to stem the spread of the deadly WNS.


The U.S. Army Says It Can Teleport Quantum Data Now, Too.

Quantum computing could revolutionize the way we interact with information. Such systems would process data faster and on larger scales than even the most super of supercomputers can handle today. But this technology would also dismantle the security systems that institutions like banks and governments use online, which means it matters who gets their hands on a working quantum system first.

Just last week I wrote about how a team of researchers in the Netherlands successfully teleported quantum data from one computer chip to another computer chip, a demonstration that hinted at a future in which quantum computing and quantum communications might become a mainstream reality.

That still seems a long way off—physicists agree that transmitting quantum information, though possible, is unstable. And yet! The U.S. Army Research Laboratory today announced its own quantum breakthrough.

A team at the lab’s Adelphi, Maryland, facility says it has developed a prototype information teleportation network system based on quantum teleportation technology. The technology can be used, the Defense Department says, to transmit images securely, either over fiber optics or through space—that is, teleportation in which data is transmitted wirelessly.

The DoD says it can imagine using this kind of technology so military service members can securely transmit intelligence—photos from “behind enemy lines,” for instance—back to U.S. officials without messages being intercepted.

But this kind of technological advance, especially in a government-run lab, is significant for the rest of us, too. Quantum computing would offer unprecedented upgrades to data processing—both in speed and scope—which could enhance surveillance technologies far beyond what exists today.

“That’s why the NSA in particular is so interested in quantum computers and would like to have one,” the physicist Steve Rolston told me last week, “and probably would not tell anyone if they did.”

300,000 mirrors: World’s largest thermal solar plant (377MW) under construction in the Mojave.

The largest concentrating solar power plant (100 MW) in operation is currently in Abu Dhabi, but it won’t stay at the top of the list for too long. Brightsource Energy is putting the finishing touches on its massiveIvanpah concentrating solar power (CSP) plant in the Mojave desert, and if all goes well, the switch should be flipped this year. Brightsource solar power project     http://www.treehugger.com/slideshows/renewable-energy/see-worlds-largest-thermal-solar-plant-370mw-under-construction-mojave-desert/ From the desk of Zedie.

NIDA Review Catalogs Cannabis Risks

“Marijuana has been associated with substantial adverse effects, some of which have been determined with a high level of confidence,” concluded a review by top officials at the National Institute on Drug Abuse (NIDA).

Regular and/or heavy recreational use of cannabis has been strongly linked with addictive behaviors, motor vehicle accidents, lung dysfunction, and “diminished lifetime achievement,” according to NIDA Director Nora Volkow, MD, and three of her deputies.

And such health problems as abnormal brain development, increased abuse of other drugs, and new-onset or exacerbated schizophrenia, depression, and anxiety have been identified in marijuana users, the review found with a medium level of confidence.

“As policy shifts toward legalization of marijuana, it is reasonable and probably prudent to hypothesize that its use will increase and that, by extension, so will the number of persons for whom there will be negative health consequences,” the officials wrote in the review, published in the June 5 issue of the New England Journal of Medicine.

Volkow — who has run NIDA since 2003 — and colleagues based their conclusions on findings in 77 previously published papers. They did not describe it as a comprehensive or systematic review, but rather as a survey of “the current state of science” on marijuana’s adverse health effects.

Although Volkow and colleagues specifically addressed recreational use, many of the underlying studies did not distinguish it from medical uses, and most of the review’s conclusions would likely apply to medical marijuana with high THC content when taken frequently.

Dependence and Gateway Drug Risk

Volkow and colleagues acknowledged that the addictiveness of marijuana has been “contentious,” but they insisted that the evidence falls strongly on the side of a strong propensity toward unhealthy dependence.

They mainly cited data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and the National Survey on Drug Use and Health (NSDUH).

The NESARC analysis, from 2011, indicated that about 9% of all first-time users will become “addicted,” which Volkow and colleagues explicitly equated with having met DSM-IV criteria for dependence. The original study authors noted that the “cumulative probability of transition to dependence” was lower for marijuana than for the other three drugs they examined (nicotine, cocaine, and alcohol), but when such transition did occur, it was relatively fast.

Data from NSDUH in 2012 suggested that some 2.7 million Americans 12 and older could be considered dependent on marijuana (compared with 8.6 million meeting criteria for alcohol dependence).

The NIDA team also referred to an estimate that “about one in six” teenagers who take up cannabis become dependent on it, one of the conclusions in a 2009 Lancet review article.

Evidence that marijuana serves as a “gateway drug” — that is, a first recreational drug that leads users to initiate other, potentially more hazardous drugs such as cocaine or heroin — was less direct. Volkow and colleagues adduced rodent data indicating that cannabinoids alter reactivity in dopamine-mediated reward pathways, and that the THC component in particular “can prime the brain for enhanced responses to other drugs.”

Although the researchers asserted that “most epidemiological studies” support “increased susceptibility to drug abuse and addiction to several drugs later in life” in those starting on cannabis, their sole reference was a single twin study reported in 2004 that had numerous limitations.

Volkow and colleagues also conceded that the associations were not necessarily causal: “An alternative explanation is that people who are more susceptible to drug-taking behavior are simply more likely to start with marijuana because of its accessibility, and that their subsequent social interactions with other drug users would increase the probability that they would try other drugs,” they wrote.

Brain Development

Animal data also point to a deleterious, or at least abnormal, effect on brain development from early exposure to cannabinoids and specifically THC — but again, studies in humans have been limited to showing associations that may or may not reflect a causal relationship.

For example, Volkow and colleagues cited studies of adults who had smoked marijuana regularly during adolescence, which found “impaired neural connectivity (fewer fibers)” in certain brain regions compared with adults who were nonusers as teens.

Similar studies have found volume and activity differences in persons with a history of marijuana use versus controls.

On the other hand, these were all cross-sectional studies that did not exclude the possibility that such differences predated the marijuana use or resulted from other environmental or genetic factors that happened to correlate with cannabis use.

Mental Illness

Numerous studies have found the following mental health risks in regular marijuana users, Volkow and colleagues indicated:

  • Increased likelihood of anxiety and depression
  • Increased likelihood of psychosis
  • Worsened symptoms of schizophrenia
  • Earlier onset of psychotic events


But, they conceded, “it is inherently difficult to establish causality in these types of studies because factors other than marijuana use may be directly associated with the risk of mental illness. In addition, other factors could predispose a person to both marijuana use and mental illness.”

Motor Vehicle Accidents

Here, Volkow and colleagues did not have to rely solely on association studies. Controlled trials with driving simulators have shown clear, dose-dependent impairments associated with blood THC levels.

Pooled data from an earlier meta-analysis showed a relative risk close to 2 for accidents involving drivers who used marijuana shortly before getting behind the wheel.

Another study showed that overall motor vehicle accident risks in individuals with detectable THC were similar to those seen in persons with blood alcohol levels higher than 0.08% (although the types and severity of accidents were not necessarily the same).

Volkow and colleagues also noted that these risks of marijuana and alcohol, which are often used together, appear to be at least partly additive.

Pulmonary Health

Because marijuana is most commonly smoked, concerns about lung effects have been raised for decades. The possibilities include lung cancer, chronic bronchitis, and pulmonary infections, as well as indirect effects such as cardiovascular events — which may stem from the psychoactive compounds in the smoke or from other components.

Volkow and colleagues found suggestions but little hard evidence that smoked cannabis increases lung cancer risk. The best study so far did find an increase compared with nonsmoking controls, but adjustment for concomitant tobacco smoking erased it.

The NIDA group indicated that the evidence is stronger that cannabis smoking promotes bronchitis and increased rates of infections, mainly in the heaviest users.

Lab studies have indicated that cannabinoids may affect vascular systems, the researchers noted — CB1 receptors are found in blood vessels, for example.

Success in School and Life

Volkow and colleagues offered a plausible causal chain connecting regular marijuana use with poor school performance. For example, since the drug impairs certain cognitive functions such as short-term memory, some impact on learning would be expected.

In turn, the researchers argued, such impacts, even if relatively brief, “will interfere with the subsequent capacity to achieve increasingly challenging educational goals.”

But they cited only one publication directly addressing marijuana use and students’ grades — a review in Addiction published in 2000, in which Australian researchers Michael Lynskey, MSc, PhD, now at King’s College in London, and Wayne Hall, PhD, of the University of Queensland in Sydney, argued against a direct causal relationship. (Instead, they suggested, “early cannabis use appears to be associated with the adoption of an anti-conventional lifestyle characterized by affiliations with delinquent and substance using peers, and the precocious adoption of adult roles including early school leaving, leaving the parental home, and early parenthood.”)

The NIDA team indicated that research on possible psychosocial effects later in life has been inconsistent. Some studies, they wrote, indicated that “long-term deficits may be reversible and remain subtle.”

Others have found associations with lower income, greater reliance on public assistance, joblessness, criminality, and “lower satisfaction with life,” Volkow and colleagues wrote — though these would also be consistent with Lynskey’s and Hall’s epiphenomenon hypothesis.


The NIDA group acknowledged that much of the human-study literature on marijuana is marred by “multiple (often hidden) confounding factors [that] detract from our ability to establish causality.”

Although those factors are often used to suggest that marijuana use is not as damaging as the crude associations might suggest, other limitations may mask even more severe risks.

For example, many of the studies were conducted more than 10 years ago, when THC concentrations in street-level marijuana were much lower than now. (Volkow and colleagues pointed to Drug Enforcement Administration data showing that THC levels have more than tripled since the 1980s.) This change in the product, the researchers suggested, puts in doubt “the current relevance of the findings in older studies … especially the studies that assessed long-term outcomes.”

They also noted the paucity of research on potential medical benefits of marijuana and its components, as well as on novel risks when prescribed for medical purposes (such as exacerbation of cognitive deficits in patients with pain states for which marijuana is sometimes recommended).