Friday, May 6, 2011

Autism & Making Hay While the Sun Shines

According to Ousseny Zerbo, a fifth-year doctoral student in the graduate group in epidemiology in the Department of Public Health Sciences in the UC Davis School of Medicine, children who were conceived during winter have a significantly greater risk of autism. The risk of having a child with an autism spectrum disorder grew progressively throughout the fall and winter to early spring, with children conceived in March having a 16 percent greater risk of later autism diagnoses, when compared with July conceptions.  So that raises the question, “Should would-be parents abstain from sex in the later Winter months to prevent their potential child from developing autism?”  If so, perhaps they could plan ahead for a late winter drought, by making up between Halloween and Thanksgiving. Just a thought.

Hmm, let’s see, I wonder whether there is really something to this seasonality business?  Disanto and colleagues reported in the British Journal of Psychiatry that they found an excess of anorexia births from March to June (i.e. individuals who starve themselves, must have been conceived in June to August).  Schwartz recently reported in Medical Hypotheses, that being born in the winter and spring, (as with autism), significantly increases one's risk for developing schizophrenia. He says this birth seasonality may account for as many as 10% of all cases of schizophrenia. And Makino and colleagues in Japan found that risk of primary childhood brain tumors was also seasonal (published in Children’s Nervous System).  A Spanish group headed by Fernandez de Abreu reported in the journal Multiple Sclerosis, that there was a significantly reduced number of individuals born in November who were later diagnosed with multiple sclerosis (February conception protects against MS). A research group in Israel, headed by Lewy, reported in Journal Pediatric Gastroenterology and Nutrition, that girls with the diagnosis of Celiac disease and children of both sexes with a family history of Celiac disease have a different pattern of seasonality of birth from the general population, with a peak of diagnosis being in July and August, corresponding with September or October conception. Do you see an overall seasonal pattern here? Me neither. 

My grandfather, Raymond Raymond Thompson (that was really his name!) fathered ten children with his wife Elizabeth, none of them had autism, schizophrenia, anorexia or brain tumors, though they all had callouses from working on the farm.  As far as I could tell Grandpa Ray and Grandma Elizabeth didn’t pay a lot of attention to the calendar when creating their family.  They were of recent Scot and English descent, and apparently believed that procreation was an activity that one simply had to tolerate, regardless of the season, as long as the woman’s health held out or she died of child birth.  Grandpa Ray Ray used to remind us grandchildren that a man had to make hay will the sun shined, so maybe there was a degree of seasonality after all.

A statistician colleague at the University of Minnesota was fond of reminding students in his classes that there was a high positive correlation between the number of churches and the number of bars in towns in Wisconsin.  At that point during his lecture, he typically put on a wry smile, gave a wink and then speculated aloud that perhaps religion drove people to drink.

As long as I can remember, well back into the 1960s, various researchers periodically reported correlations between birth season of the year, and one or another health condition.  Nearly always, after publishing one or two articles, the researchers moved on to another topic, since almost never did anything come of such birth seasonality findings, though they were always intriguing, leading to a lot of speculation and suggestive cocktail conversation.

If a relation between birth season and autism prevalence is ever firmly established, which I doubt, it will be small and very likely a proxy for some other factor, such as Vitamin D levels, which vary with exposure to sunlight. If there is any relation, it will only apply to a small subset of individuals with autism. So far, nothing much has come of those Vitamin D and seasonal viral autism hypotheses, though you will find lots of them out there on the internet if you do a Google search. 

So if you know someone who is planning to go on their second honeymoon next February or March, you can tell them it’s probably safe to start checking out resorts in Oahu, Cancun or Capri. 

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