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P Value Under Fire

coinflipThe greatest strength of science is that it is self-critical. Scientists are not only critical of specific claims and the evidence for those claims, but they are critical of the process of science itself. That criticism is constructive – it is designed to make the process better, more efficient, and more reliable.

One aspect of the process of science that has received intense criticism in the last few years is an over-reliance on P-values, a specific statistical method for analyzing data. This may seem like a wonky technical point, but it actually cuts to the heart of science-based medicine. In a way the P-value is the focal point of much of what we advocate for at SBM.

Recently the American Statistical Association (ASA) put out a position paper in which they specifically warn against misuse of the P-value. This is the first time in their 177 years of existence they have felt the need to put out such a position paper. The reason for this unprecedented act was their feeling that abuse of the P-value is taking the practice of science off course, and a much needed course correction is overdue. (more…)

Posted in: Science and Medicine

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Bad Reporting about Uploading Memories

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The Mirror declares, ‘Scientists develop Matrix-style technique of ‘feeding’ information directly into your brain.’ Discovery News went with, “Novices ‘Download’ Pilots’ Brainwaves, Learn To Fly.” Most other outlets spoke of ‘uploading’ information to the brain, and learning in seconds.

The one thing I was certain of from reading these headlines is that this was not what was happening. Brain-machine interface technology is progressing rapidly, but we are a long way away from downloading information from or uploading information to the human brain.

The news outlets reported that electrical activity was recorded from pilots and then used to stimulate the subject. They also reported that this enhanced learning by 33%.

What actually happened

Here is the actual study: “Transcranial Direct Current Stimulation Modulates Neuronal Activity and Learning in Pilot Training.”

(more…)

Posted in: Neuroscience/Mental Health

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Air Pollution and Public Health

airpollution

Public health measures are those not aimed at individuals but at society as a whole, or subgroups within society. Physicians are charged not only with promoting the health of their own patients, but as a profession we (and health care professions in general) are charged with promoting the public health.

Public health measures, however, are highly likely to cross into politically charged areas. This should not deter the promotion of public health.

Issues that we deal with regularly involving public health include vaccination programs and laws surrounding vaccine requirements, fluoridation of public water supplies, helmet laws, and even gun laws. We have never, however, written about air pollution as a public health concern (except for dubious claims that air pollution is linked to autism).

The health risk of air pollution

Air pollution as a health risk is nothing new, but several recent studies are focusing attention on this issue. Recently the Royal College of Physicians produced a report in which they claim that 40,000 deaths per year in the UK can be attributed to poor air quality, both indoors and outdoors. (more…)

Posted in: Epidemiology, Public Health

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Organic vs Conventional Meat and Milk

cow-eating-grassTwo recently published meta-analyses, one on meat and another on milk, conclude that levels of polyunsaturated fatty acids (PUFA) and omega-3 fatty acids are higher in the organic versions of both. This is being widely reported as evidence that organic meat and milk is healthier, but a closer look at these two studies shows a different picture.

The organic false dichotomy

I am going to start with what I consider to be the biggest problem with how both studies are being presented and reported. This relates to a deeper issue – the false dichotomy of organic vs conventional. In my opinion, we should use whatever farming techniques prove to be best (for the quality of the food, sustainability, cost-effectiveness, and environmental impact) regardless of whether or not they are considered organic.

While proponents of organic farming claim that for them food quality and sustainability are the real issue, they aren’t. Organic techniques are based on the appeal to nature, not an evidence-based approach to best practices. (more…)

Posted in: Nutrition

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Update on the Zika Virus

zika-virus-mosquitoA new word has been added to the public’s vocabulary – the Zika virus. It seems we have one more infectious agent to worry about. Here are the facts as we currently understand them regarding the recent Zika epidemic, and also some rumors and conspiracy theories that need debunking.

Zika virus

The Zika virus (of the viral family Flaviviridae, an Arthropod-Borne or arbovirus) is spread through Aedes mosquito bites, the same mosquitoes that also spread dengue fever, West Nile, and yellow fever. The infections themselves are usually mild, causing fever, rash, joint pain, and conjunctivitis. Many of those infected (about 80%) may even have a subclinical infection, meaning they do not notice any symptoms.

According to the World Health Organization:

Zika virus is diagnosed through PCR (polymerase chain reaction) and virus isolation from blood samples. Diagnosis by serology can be difficult as the virus can cross-react with other flaviviruses such as dengue, West Nile and yellow fever.

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Posted in: Public Health, Vaccines

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Laws Limiting Vaccine Exemptions Work

VaccineIt’s nice when a question can be resolved with objective numbers of unequivocal outcomes. Subjective outcomes give scientists a headache.

In this case we are talking about the effect of vaccine exemption laws on vaccine compliance rates. The question here is not the ethical one, the rights of parents to determine the fate of their children vs the right of the state to protect the health of children and the public health. I think the latter trumps the former, but some disagree.

Regardless of what you feel about the ethical question, we need to know if the laws we pass to achieve our goals actually work, or if they don’t work, or even have unintended consequences. Having an admirable goal is not enough; when you make actual decisions (practice decisions, policy decisions, healthcare decisions for you and for family) you want to know that those decisions are having the desired effect.

(more…)

Posted in: Legal, Public Health, Vaccines

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More Trouble for Antioxidants

Antioxidants are better acquired through food than pills.

Antioxidants are better-acquired through food than pills.

Antioxidants are now an iconic example of premature hype making its way into marketing and the public consciousness long before the science is adequately understood. There are multiple lessons to be learned in this story, and a new study just emphasizes those lessons further.

A brief history of antioxidants

One of the unavoidable consequences of metabolism (burning food for energy) is the creation of oxygen free radicals, or reactive oxygen species (ROS). These are molecules that are highly reactive. They essentially contain oxygen with an extra electron, which can react with another molecule, breaking bonds and causing damage.

As you might expect, the body has natural antioxidants which react with ROS to form benign molecules.

In the 1990s it became increasingly apparent that oxidative stress was playing an important role in cell damage, even sometimes triggering apoptosis, or programmed cell death. Many degenerative diseases, like Alzheimer’s disease, were shown to be driven in part by oxidative stress. In addition, it seemed that ROS play a role in aging.

(more…)

Posted in: Herbs & Supplements, Nutrition

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The Clean Eating Delusion

eating-clean-november-400px

While some parts of the world are concerned with eating, because of food insecurity, the “worried and well-fed well” are increasingly obsessed with so-called “clean eating.”

This is nothing new, but like every cultural phenomenon, it seems, has increased partly due to the easy spread of misinformation over the internet. If you are anxious about your health, and who isn’t to some degree, your anxiety is fed by a steady diet of pseudo-experts, con-artists, and internet personalities telling you about all the things you eat that adversely affect your health.

This phenomenon is increasingly being recognized as a health issue among experts. In 1996 Dr. Steven Bratman proposed a formal disorder he calls orthorexia nervosa. He writes:

For people with orthorexia, eating healthily has become an extreme, obsessive, psychologically limiting and sometimes physically dangerous disorder, related to but quite distinct from anorexia.

(more…)

Posted in: Nutrition

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HPV Vaccine Safety and Acceptance

HPV vaccine smallThe public fight over the human papillomavirus (HPV) vaccine is still raging. The debate partly reflects the underlying logic of health prevention measures, which is essentially a statistical game of risk vs benefit. Unfortunately thrown into the mix are ideological opponents to vaccines who are distorting the facts at every turn.

Notice that I said this was a “public” fight, because it is not a serious scientific dispute. There is sufficient evidence to confidently conclude that the HPV vaccines currently available are safe and effective. All medical interventions will contain some risk, it is never zero, but vaccines in general, and the HPV vaccine specifically, have minimal risks and clearly prevent disease.

In addition there is a social angle to the HPV vaccine in that it is given to children to prevent a sexually transmitted disease.

The science of the HPV vaccine

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Posted in: Public Health, Vaccines

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FTC Slaps Down “Brain Training” Claims

lumosity-banner-1Lumosity is a company that provides online and mobile games that it claimed are scientifically designed to enhance memory, focus, mental flexibility, and even stave off dementia. In a recent decision, the Federal Trade Commission (FTC) concluded that Luminosity’s claims are not based on adequate scientific evidence. They imposed a $50 million judgement against Lumos Labs, the company who sells Lumosity, and allowed them to settle for $2 million.

Being mentally active

The idea behind “brain training” is not a bad one, it’s just easy to misrepresent as something it isn’t. The basic notion is that using your brain makes it function better. It is better to be mentally and physically active than inactive. This overview summarized the evidence: (more…)

Posted in: Neuroscience/Mental Health

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