I’ve written a lot about the biases inherent in commercially sponsored medical research. Research funded by private individuals and foundations isn’t necessarily objective either. As Michael Segal, MD, PhD points out in this guest commentary, autism researchers who are funded by patrons who have autism in their families may avoid hypotheses that could even indirectly implicate the role of environmental factors (e.g., parenting styles).
Here is Dr. Segal’s view:
The main front page article in the 15 December Wall Street Journal was about a hedge-fund leader spending $138 million to find a genetic basis for autism (click here for a free link ). According to the WSJ he is “pushing scientists to probe a genetically based explanation for the disease … often passing over established autism groups or those with differing theories”.
It is refreshing to see a widening public discussion beyond the hypothesis about mercury in vaccines, but it would be unfortunate if people went off to the opposite extreme and assumed that environmental causes could be ignored. Indeed, one would have to assume at least some environmental input if there is a real increase in the incidence of autism rather than simply an increase in diagnosis.
In particular, one fears that a discussion polarized between genetics and environment might ignore hypotheses that involve interactions between genetics and environment. In the spirit of Eric Kandel, who often dismissed charges that he was speculating by saying “our thoughts are ahead of our data”, here are three speculative hypotheses about how genetics and environment could interact to produce autism. Listing three hypotheses is intended to signal that people should not get over-invested in these hypotheses since at least two of the hypotheses are likely to be wrong, unless of course autism is a final common pathway with many initiators.
1. Autism can result from the human equivalent of the Harlow monkey experiments. In classic experiments by psychologist Harry Harlow
, a deficiency of parental contact produced life-long “autistic-like” symptoms. Could modern innovations such as child-carrier seats and pharmacological intervention for “colic”
be producing autistic-like symptoms in individuals with particular sensitivity genes
2. Autism can result from genes that have harmful effects that are only expressed with our modern diet. In hypokalemic periodic paralysis, symptoms are observed typically after a meal composed of readily digestible carbohydrates
, presumably due to potassium levels dropping suddenly as potassium enters cells in co-transport with glucose after a bolus of glucose. When our ancestors were eating a different diet, this gene was less problematic since meat, vegetables and whole wheat do not result in such a large glucose bolus. Hypokalemic paralysis has been shown to result from sodium or potassium channelopathies in muscle. It would not be surprising to find similar channelopathies in sensory nerve or brain that could produce behavioral effects interpretable as autism; indeed, researchers are already identifying cohorts in which there seem to be behavioral abnormalities attributable to such channelopathies and are looking for mutated genes.
3. Autism could result from toxins in diet that affect susceptible individuals. Although the vaccine opponents may be “galloping off in the wrong direction” in their concerns about tiny amounts of mercury in childhood vaccinations, there are far larger amounts of mercury in tuna fish, a food increasingly consumed in recent decades, often by pregnant women. Some fetuses may be more susceptible than others to such levels of mercury.
Hopefully such mixed genetic-environment hypotheses will not get ignored by people focused on pure environmental or pure genetic explanations. In particular, one hopes that funding by people with individuals with autism in their families will not be taken as pressure to avoid any hypothesis in which the family did anything “wrong”, even if the behavior was one as seemingly innocuous as using child carriers instead of holding babies, serving macaroni or eating tuna fish. Fortunately, the WSJ article states that Gerry Fischbach will “work part-time leading the foundation’s scientific strategy”, which gives me confidence that the money will be used with the broad and open thinking needed to approach the problem of autism.
December 18, 2005