Monthly Archives: May 2015

Evidence-based living

Chocolate causes you to lose weight. Or does it?

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So, this person who made a bunch of open access journals look like the fools they are a while back (turns out most don’t actually do peer review – whoops!) just posted about a more recent sting, this time on the science media.

Basically, they carried out a study that showed chocolate helps you lose weight, and reported it as such.

It was then spread far and wide for obvious reasons.

Mainly because chocolate is delicious and most of us want to keep eating it without gaining the weight it seems to drag along with it.

Turns out it was a crappy study, on purpose.

The authors say they purposely engaged in a practice called p-hacking, which is pretty common in science unfortunately. Basically, the researchers measured a whole bunch of other variables too, so by random chance you might expect some of them to LOOK like chocolate affects them.

I read as their main point that science media sensationalizes everything scientists find without really asking how much support there is for the conclusion they are spreading around the world.

The only problem is I keep coming back to their study. They DID find that chocolate helps you lose weight. Their ‘extra’ variables were things like blood protein, sodium, etc., which in my opinion are things that I wouldn’t expect chocolate to affect anyways.

Hmm. So, clearly, science media sensationalize everything without regard to the quality of the research.

But I keep coming back to the important question – can chocolate help me lose weight? (Or rather, can I keep eating lots of chocolate but do something about my ever-growing midsection?)

I’m going to conclude that the authors set up a bunch of ‘straw man’ hypotheses they didn’t really believe in to prove a point, and that they in fact were NOT engaging in p-hacking. Maybe I’m being nitpicky, but I don’t see chocolate affecting sodium as that good of a hypothesis.

BUT on the other hand the main points they made were really good! I keep going around in circles on this…

Whatever. I don’t think I’ll be able to solve this tonight.

I’m gonna go eat some chocolate.

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Evidence-based living

What ACTUALLY causes autism? Here are 7 possibilities.

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Fresh from listening to some of my Facebook friends argue about vaccines, a question occurred to me. What DOES cause autism? Not the MMR (measles-mumps-rubella) vaccine (see for example, Jain et al. 2015. Also, the weight of a huge amount of scientific evidence vs. one tiny, discredited study. I will fight you). But SOMETHING causes autism, so what is it? Much of the following is a summary of “Environmental factors in autism” by Andreas Grabrucker (2013).

So, t1024x1024 Wallpaper rain man, tom cruise, dustin hoffmano start, what actually IS autism?

Autism is a developmental brain disorder, generally classified on a spectrum (autism spectrum disorder or ASD), meaning it can vary in severity and symptoms among people. Interestingly, although most people with autism can’t count toothpicks really fast like Dustin Hoffman in Rain Man, his character was actually based on a real person. Among the most common symptoms of ASD are impaired social behavior and repetitive behaviors.

Some autism advocates believe terms like ‘disorder’ and ‘impairment’ are loaded, and don’t like them. I use them here for consistency with medical and research terminology, but it is a good thing to be aware of.

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Autism has a genetic component, meaning it can run in families (Abrahams and Geschwind 2010). However, autism risk is strongly affected by the developmental environment as well. Here are the environmental factors most strongly linked to autism. Note that although some of these are likely causal, others may just co-occur with autism often.

Risk factors during pregnancy

1. Prenatal virus, allergy, or auto-immune disease – thought to alter immune function in the placenta or fetus

2. Zinc deficiency – very common in autistic children, may represent a physiological mechanism, may relate to infections

3. Abnormal melatonin synthesis – melatonin is an important hormone, abnormalities may relate to light pollution or zinc

4. Maternal diabetes – linked to a two-fold increase in autism risk, mechanism here is unclear

5. Stress and trauma during pregnancy and birth – may be related to immune function, can cause similar behaviors in other animals

6. Some chemicals that negatively affect humans (‘toxins’) – for example, pesticides, valproic acid, and thalidomide

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7. Advanced age in either parent – may be due to increased mutation risk or increased risk of pregnancy complications

Postnatal risk factors

There are not currently well-supported risk factors for autism that occur after birth. This may change, as some are being investigated, but none are strongly supported at this point.

In conclusion, risk factors for autism may be most important during pregnancy, and certainly seem to be linked to immune function, stress, certain toxic chemicals, and pregnancy complications. What we are still missing is a unifying physiological hypothesis tying these together in a meaningful way that incorporates the genetic risk.

References

1. Jain, A., Marshall, J., Buikema, A, Bancroft, T., Kelly, J.P., Newschaffer, C.J. (2015). Autism occurrence by MMR vaccine status among US children with older siblings with and without autism. Journal of the American Medical Association. 313 (15): 1534-1540.

2. Grabrucker, A.M. (2013) Environmental factors in autism. Frontiers in Psychiatry 3 (118).

3. Abrahams, B.S., Geschwind, D.H. (2010) Connecting genes to brain in the autism spectrum disorders. Arch. Neurol. 67, 395-299.