Yesterday I put up a little post discussing a very theoretical possible link between acetaminophen and autism. The main point is that acetaminophen is known to gobble up glutathione like gangbusters, and some of us will be more vulnerable to this glutathione destruction than others.
Glutathione is a major part of the body's detoxifying systems. When we burn fuel and various other biochemical things, we create toxic byproducts. These toxins can damage DNA and make systems inefficient and ragged, and call up our inflammatory army to clear the damage, which can cause its own problems. Since our body is a tiny little ecosystem, we have our own chemical clean-up crew that should be johnny on the spot to sop up free radicals and other untoward elements. We can measure how good our clean-up crew is in various ways, and a couple of very small studies have demonstrated that kids with autism don't seem to be very good at dispensing with toxins. In this Egyptian paper (1), kids with autism have lower rates of superoxide dismutase and glutathione peroxidase than matched control children (this could mean they make less or are dealing with more oxidation than other kids, so the enzymes are used up faster). These two enzymes clean up superoxide and the resultant hydrogen peroxide, reducing them to less dangerous downstream products. I have also reviewed a study showing inefficient and dirty mitochondria in children with autism compared to controls.
|A free radical courtesy Flickr Creative Commons|
Children under 3 not only grow at a rapid rate, they also seem to have naturally low glutathione levels, making them among those particularly vulnerable to oxidant injury (2). Children who have genetic inefficiency in the antioxidant system will therefore be even more vulnerable. The brain, being a high energy and relatively delicate organ (the liver has an astonishing capacity to regenerate cells, whereas the brain has almost no capacity to regrow cells but can modulate connections to bypass injured systems to some extent) will be especially susceptible to oxidative damage. Another area vulnerable to lack of glutathione? Our delicate airways -- one of the reasons perhaps some children eventually "grow out" of asthma.
Guess what else is exceedingly important in establishing an amazing and efficient antioxidant system? That's right. Micronutrient status. Copper and zinc need to be topped up in order to make plenty of superoxide dismutase, for example.
You know who else tends to have a less efficient antioxidant-making system and lower amounts of glutathione? Yes, the elderly. As I've mentioned in the past, the pathophysiology of autism and dementia seem to have some similarities -- a similar puzzling and devastating process of inflammation and neuronal cell death occurring at entirely different developmental stages.
These are all complex processes with many players, internal and external. That's why I don't think there is any "one" cause of the autism spectrum disorders (or the dementias, for that matter). However, combine a genetic vulnerability, low zinc status, maybe some acetaminophen, and inflammatory insult, and ultimately there is a straw that breaks the camel's back.
The good news is that most of us are resilient and can handle a bit of acetaminophen here and a bit of red #5 there, and some of us sail through life smoking cigarettes and chomping on funky fries. The bad news is that some of us aren't as resilient, and one way or another we will all have to pay the piper.