For several years I have been doing simple daily tests to measure my brain function. I got the idea when I noticed that a few capsules of flaxseed oil improved my balance. Flaxseed oil also improved other measures of brain function, such as digit span. I wasn’t surprised I could do better; what was surprising was how easy it was. It revealed a big gap in our understanding of nutrition. I do the daily tests not only to improve brain function but also to improve the rest of my body. I think the brain is like a canary in a coal mine — especially sensitive to bad environments. Learning what environment was best for the brain would suggest what environment is best for the rest of the body. When I started taking an optimal amount of flaxseed oil, my gums turned from red (inflamed) to pink (not inflamed), supporting this assumption.
I tried six or seven mental tests and eventually settled on a test of arithmetic (how fast I could do simple problems such as 5-3). I hoped that now and then my score would change (in either direction, faster or slower) and that these changes would point to new things that control brain function. No one had/has done such a thing. I had no idea if unexpected changes would show up or, if they did, how often. I didn’t know what the score changes would look like (their size and shape) nor, of course, what would cause them. Would all of them involve diet? Would all of them make sense in terms of what we already know? (Flaxseed oil makes sense because the brain contains lots of omega-3.)
The first two surprises were these: 1. My score suddenly improved a few days after switching from Chinese flaxseed oil to American flaxseed oil. This made sense: It is easy to destroy omega-3 if flaxseed oil is kept at room temperature. 2. My score suddenly improved when I switched from pig fat to butter. This was counter-intuitive: pig fat is more paleo than butter.
Last fall, there was another surprise: My score greatly improved since the summer. I was much faster than ever before. At first I thought the improvement was due to moving to Beijing. I had moved from Berkeley to Beijing in early September. My Beijing life differed in a thousand ways from my Berkeley life. I had three ideas about which differences might matter. 1. Walnuts. Perhaps I ate more walnuts in Beijing. Walnuts are supposed to be good for brain function. 2. Heat. It was much hotter in Beijing than Berkeley. Maybe that improved brain function. 3. Vitamins. I took less vitamin supplements in Beijing. Maybe they harmed brain function.
I tested these possibilities. 1. I stopped eating walnuts. My arithmetic score did not clearly change. 2. Winter came, it got much colder. The improvement did not go away. 3. I took the same amount of vitamins I’d taken in Berkeley. My arithmetic score didn’t change. So all of these ideas were wrong.
Because they were wrong, I considered a fourth possibility: The improvement was due to removal of two mercury amalgam fillings on July 28, 2010. They were replaced with non-amalgam fillings. I’d had them removed for precautionary reasons. I wasn’t suffering from any signs of mercury poisoning. Hair tests had repeatedly shown mildly high amounts of mercury in my hair (75th percentile of an unspecified sample). Measurements of the mercury in my breath had come out higher than usual but it was hard to be sure the machine was working correctly.
I looked again at my data. It showed something I hadn’t noticed: the improvement started before I went to Beijing. It started very close to July 28. That was good evidence that the mercury explanation was correct. Now the evidence is even stronger. I’ve returned to Berkeley and thereby made my life quite similar to the situation when my scores were much higher than now. The improvement has remained.
The evidence for causality — removal of mercury amalgam fillings improved my arithmetic score — rests on three things: 1. Four other explanations made incorrect predictions. 2. The improvement, which lasted months, started within a few days of the removal. Long-term improvements (not due to practice) are rare — this is the only one I’ve noticed. 3. Mercury is known to harm neural function (“mad as a hatter”). As far as I’m concerned, that’s plenty.
A long Wikipedia article describes evidence on both sides of the question of whether mercury amalgam fillings cause damage. In 2009, the American Dental Association stated in a press release “the overwhelming weight of scientific evidence supports the safety and efficacy of dental [mercury-containing] amalgam.” As recently as 1991, Consumer Reports told readers “if a dentist wants to remove your fillings because they contain mercury, watch your wallet.” (Dental insurance will pay most of the cost of removing my remaining amalgam fillings.) In an essay last revised in 2006, Stephen “Quackwatch” Barrett explained at length why mercury toxicity is a “scam”. According to Barrett, “there is overwhelming evidence that amalgam fillings are safe.”