Friday, July 1, 2011

Spurious Correlations: Bars and Churches

You've likely heard that there is a positive correlation between the number of bars and the number of churches in small towns, which raises the question, "Do churches drive people to drink?"  Or maybe drinking causes people to attend church?

Periodically I receive email messages from helpful people commenting on the connections they see between autism and other conditions or events, usually vaccines, but sometimes other health conditions, most often gastrointestinal problems but occasionally other neurological conditions as well.

I received a very touching note recently from a person who read one of my blog entries in which I mentioned I have Meneire’s Disease, a progressive disorder of the inner ear associated with ringing of the ear, severe vertigo, vomiting and loss of low frequency hearing.  The empathetic email writer suggested that Meniere’s is related to autism, B12 deficiency, herpes virus infection, including chickenpox and shingles, candida infection, celiac disease, thyroid insufficiency, migraine disorder (Migraine-Associated Vertigo), Lyme Disease and Vitamin D deficiency.  Another website suggested Aspartame, MSG, HVP, Cysteine, HSV-1 virus and Lack of lipase enzyme are all causes or probable causes of Meniere’s (and by implication, may also be related to autism).  Many of such helpful people believe Meniere’s Disease and Autism are autoimmunie disorders, which while an interesting idea is far from proven to be the case.

While it is possible autism and Meniere’s Disease may be related (I received another message from an English physician suggesting such a connection), it seems unlikely damage to a centimeter of my inner ear could be selectively caused by all of those very different factors. There actually is a correlation between susceptibility to migraine and susceptibility to Meniere’s Disease.  That may make a little more sense since they are both related to blood vessel diameter in the head, which seems to be regulated by the release of the neurochemical, serotonin inside the brain and also among blood vessels on the surface of the skull, like the temporal artery.  Some Meniere’s correlations make sense, like consuming too much sodium increases fluid retention (including in your ears), drinking too much coffee or alcohol tends to increase blood vessel diameter, same deal.  Those are not causes, they are non-specific exacerbating conditions.  These are a bit like the admonition, “If you have a headache, stop banging your head against the wall.”

I mention this because it is very easy to get snookered into seeing correlations between things that are entirely spurious and reveal nothing regarding the cause of the condition of interest, such as autism. There is a professional journal devoted to such issues, the Journal of Spurious Correlations.  There are also correlations that are epiphenomenal, i.e. they are caused BY the condition rather than being a cause OF the condition.  Example: Children with autism are often very finicky eaters and fail to eat a balanced diet, which makes them prone to gastrointestinal problems, such as constipation, or in some cases when too much juice is consumed, loose-stools.  Parents see the gastrointestinal problem and conclude that a GI disorder is a biological cause of autism, rather than a result of having autism.

So, thanks for your thoughts about Meniere’s Disease and autism and other possible related conditions.  In the meantime I’m going to keep an eye on research being reported by the Meniere’s Society, a scientific organization devoted to diagnosis and treatment of the condition based in the UK and the National Institute on Deafness and Other Communicative Disorders in the US.

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