A recently published epidemiological study in JAMA Pediatrics looked at the association between induction and enhancement of labor and the risk of autism. The researchers found a positive association, especially with males. The study has been variously reported in the popular press with causal interpretations not justified by the data.
The study itself is very robust – the authors looked at 625,042 live births, including 5,500 children with a diagnosis of autism. They found:
Compared with children born to mothers who received neither labor induction nor augmentation, children born to mothers who were induced and augmented, induced only, or augmented only experienced increased odds of autism after controlling for potential confounders related to socioeconomic status, maternal health, pregnancy-related events and conditions, and birth year. The observed associations between labor induction/augmentation were particularly pronounced in male children.
Although this is a large study, it is one study, and so the correlation needs to be independently confirmed. But if we assume the correlation is accurate, the next question is – what is the arrow of causation? Observational studies can only indicate an association. By themselves they cannot prove causation, although multiple observational studies may be able to triangulate to the most likely causal interpretation. (more…)
Those who cannot remember the past are condemned to repeat it.
– George Santayana
Science-based medicine is more than a set of methods or certain philosophy of medicine – it is an entire approach to what should be the core questions for any interventionist profession: is it real and does it work?
These are often deceptively difficult questions to answer. Fortunately we have at least a century of experience applying systematic methods to answering these questions within the context of medicine. This is a wealth of history from which to learn, full of cautionary tales and enlightening examples.
However, as Winston Churchill lamented, we tend to forget the lessons of the past leading to, “…the most thoughtless of ages. Every day headlines and short views.”
Part of the mission of science-based medicine (and skepticism in general) is to remember the lessons of the past as they relate to science and pseudoscience, and to constantly remind the public and our colleagues of these lessons.
Yoga is an increasingly popular form of exercise in the US. According to Yoga Journal more than 20 million Americans use yoga as their form of exercise. As a form of exercise yoga is fairly straightforward, involving stretching and holding poses that strengthen muscles. It also carries the generic benefits of any exercise in terms of calorie-burning and cardiovascular health.
Yoga, however, is more than exercise – it also comes with a “spiritual” angle. The term itself refers to a number of practices originating in ancient India meant to strength mind, body, and spirit. For this reason it has become a popular target for marketing the latest health pseudoscience. You will be hard pressed, in fact, to find a yoga class that does not incorporate some degree of outright woo, the only question really is not if, but how much. This is unfortunate because yoga may be an effective alternative for low-impact exercise.
There is some evidence that yoga, for example, is effective in relieving low back pain, although it may not be more effective than usual care. There is a lack of quality studies comparing yoga to other forms of exercise, and so we may just be seeing the generic benefits of exercise. Still, if the classes are fun and they keep people motivated to continue their exercise regimen, that is useful.
Yoga, therefore, fits into a more general phenomenon of marketing a specific intervention as if it has specific benefits, when in fact it only has generic benefits. For example, there are many studies showing that transcendental meditation is effective for lowering blood pressure. However, studies generally compare TM to no intervention, not to other forms of relaxation. The parsimonious interpretation is that TM confers the generic benefits of relaxation, but there is no evidence to suggest it confers any specific benefits.
Mercury in unequivocally a neurotoxin. It is especially damaging to the developing brain. But it’s the dose that makes the toxin, and so a low enough exposure even to something known to be potentially harmful may not be. Further, the body has mechanisms for dealing with toxins, and toxins in the body may not be reaching the cells they can potentially damage in significant amounts. Therefore if we want to know if a potential toxin is actually causing any harm to people we need to do some type of epidemiological study – correlating exposure to possible adverse outcomes. All the studies in petri dishes and with cell cultures just won’t answer the question of harm.
The question of whether or not mercury in vaccines has caused neurological harm, specifically autism, has been largely answered. Numerous studies have shown no association between the amount of mercury exposure from vaccines and the risk of developing autism. A separate mercury-related question, however, is whether or not there is any risk of harm from mercury exposure from seafood. Mercury is methylated by bacteria into methymercury, and through them gets into the food chain in the oceans. Fish that eat other fish then concentrate the mercury in their tissues, and so predatory fish and sea mammals tend to have high concentrations of methymercury.
This has led to some precautionary recommendations, including that pregnant women should not eat tuna or other fish with high mercury levels. This makes sense, but what is the actual risk? The precautionary principle can also cut both ways. Fish contain many high-quality nutrients important for a developing brain, such as polyunsaturated fatty acids. Removing this food source from the diet of pregnant women may have unintended negative consequences.
The internet is a fabulous resource of information. It is one of those technological innovations for which you soon can no longer imagine how you lived without it. I certainly cannot imagine a project like science-based medicine prior to the web.
The web, however, is also a tremendous source of misinformation, opinion, and ideology. Also the volume of information, good and bad, can be overwhelming. We therefore are frequently asked the meta-question of how we conduct our research into specific topics, or how can the average layperson do their own research online.
Efficiently and effectively researching a complex topic is complex. It is a skill that needs to be developed, and it is especially difficult without having detailed knowledge of the specific topic ahead of time. Therefore there is no simple answer to this question, but I can offer some tips.
There are two main resources I use when searching a topic, Google and PubMed. They each have their strengths and weaknesses. For the average user, Google (or whichever general search engine you prefer) is likely going to be your first stop.
In the last decade or so there has been increasing research into non-invasive brain stimulation techniques for a variety of conditions. These include transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), random noise stimulation (tRNS), and transcranial magnetic stimulation (TMS). These techniques alter the excitability of neurons in the brain, seem to have an effect on plasticity (the ability to form new connections), and can modulate the activity of brain networks.
Overall the current research is preliminary but encouraging. Many of the details of exactly how to apply this new technology, however, are still being worked out. One recent review summarizes this complexity:
tDCS can be used to manipulate brain excitability via membrane polarisation: cathodal stimulation hyperpolarises, while anodal stimulation depolarises the resting membrane potential, whereby the induced after-effects depend on polarity, duration and intensity of the stimulation. A variety of other parameters influence tDCS effects; co-application of neuropharmacologically active drugs may most impressively prolong or even reverse stimulation effects. Transcranial alternating stimulation (tACS) and random noise stimulation (tRNS) are used to interfere with ongoing neuronal oscillations and also finally produce neuroplastic effects if applied with appropriate parameters.
It is always gratifying to see regulatory agencies actually do their job. If those regulatory agencies whose job it is to protect the public from false or harmful medical advertising, products, or services thoroughly did their job, so-called “alternative medicine” would cease to exist.
Recently the Advertising Standards Authority (ASA) in the UK issued a judgment about advertising for homeopathy, specifically by the Society of Homeopaths. They had been receiving a number of complaints. After thorough investigation, and considering the response from the homeopaths, they came to two basic conclusions: homeopaths are engaging in false advertising by claiming that homeopathy is a proven treatment for specific indications when the evidence does not support those claims, and homeopaths sometimes “discourage essential medical treatment for conditions for which medical supervision should be sought.”
The ASA specifically investigated the following advertising and claims: (more…)
Finding a simple fix for complex problems is highly appealing, which drives a persistent market in simple fixes, whether or not they are actually effective. The growing “brain training” industry is an example of this – the concept being that performing simple tasks, such as playing particular games, can have wide-ranging cognitive benefits. Unfortunately the evidence has not been kind to this notion.
Related to the brain training concept is auditory integration training. One permutation of this, the Tomatis Method, describes it this way:
The sound message is correctly heard but poorly analyzed in an emotional framework. The brain protects itself by constructing barriers that can result in the development of various disorders.
You can do the listening sessions repeatedly by using specially designed devices that stimulate the brain and progressively help it more effectively analyze the sensory message.
Your ear is not used only for hearing. It also stimulates your brain and establishes your balance. Well-tuned listening is therefore an essential component for promoting personal development.
This is a common approach to marketing such therapies – argue that one factor is a dominant cause of a host of problems, describe the method for addressing that one factor, which then leads to a happy, healthy, fulfilling life. This marketing formula appears well established. (more…)
About a year ago the editors of Anesthesia & Analgesia solicited a written debate on whether or not acupuncture is effective or simply an elaborate placebo. Four experienced acupuncture researchers agreed to write the pro-acupuncture article, Wang, Harris, Lin and Gan. They asked David Colquhoun to write the con position, and David asked me to write it with him (which, of course, I enthusiastically agreed to do).
The article is fortunately published in open access, and so I can reprint it here (full article is below). What I think David and I convincingly demonstrated is that, according to the usual standards of medicine, acupuncture does not work.
Let me explain what I mean by that. Clinical research can never prove that an intervention has an effect size of zero. Rather, clinical research assumes the null hypothesis, that the treatment does not work, and the burden of proof lies with demonstrating adequate evidence to reject the null hypothesis. So, when being technical, researchers will conclude that a negative study “fails to reject the null hypothesis.”
We accept certain risks for the benefits of modern society. We pump explosive gas into homes, we run wires with potentially fatal electrical currents through our neighborhoods, and we ski at breakneck speeds down mountains for fun.
We also allow people to operate vehicles weighing thousands of pounds at speeds that are potentially deadly if a mishap occurs. In 2011 there were 32,367 motor vehicle deaths in the US (10.4 per 100,000 population). Interestingly, this is down quite a bit from previous years. As a percentage of population the highest motor vehicle death year was 1935, with 34,494 deaths, or 27.1 per 100,000. The highest absolute number of motor vehicle deaths was in 1970, at 52,627.
The number of deaths has been mostly trending down since 1996, which is interesting because over this same period of time cell phone use has risen tremendously. There are various reasons for the decreased in fatalities – helmet laws, seatbelt laws, cracking down on drunk driving, increased car safety, and intermediate drivers licenses for new drivers to name a few. These trends have probably obscured any increase in car accidents from using portable communication devices while driving.