There are literature that suggests that mercury toxicity may increase risk of Alzheimer’s. The two largest source of mercury exposure is dental amalgams and consuming fish.
The MedScapte article Mercury Exposure May Contribute to Alzheimer’s Risk writes …
“Inorganic mercury, which is still widely used in dental amalgams, is likely a contributing cause of Alzheimer’s disease (AD) according to a systematic review of 106 studies…”
Whether someone’s level of mercury is toxic or is a concern or not depends on the individual person. A level of mercury that is perfectly fine for one person may be a problem for another person. It all depends on your genetics as to whether you are a good detoxifier or mercury or not and your current state of health and other conditions.
Further complicating things, testing and interpretation one’s mercury level can be quite tricky. It is not easy to get an accurate interpretation of a mercury test results, be it hair test, blood test, or urine test. Let’s say mercury is high in the hair. What does that mean? Could it be that you are good detoxifier and are able to excrete mercury readily in the hair and hence have a low load in the body? Or is it because your body burden is so high of mercury that it is coming out of your hair?
Should Mercury Dental Amalgams Be Removed?
Similarly, whether to remove mercury dental amalgams or not is very personal decision. Only you can answer that question. Some people have been harmed by the removal process which disturbs and exposes the mercury and other have benefited from no longer having the mercury in their mouths. There are a lot of factors involved including your genetics, detoxification ability, state of health, skill of the dentist, and the state of the filling.
Of course if you are putting in a new filling for a new cavity, then use mercury free fillings which are now widely available. If you do decide to remove existing mercury filling, find a qualified “mercury dentist” by using some of the resources recommended in this YouTube video where Dr. Mercola interview Dr. Shade.
Similar controversy revolves around EDTA Chelation therapy. Some people got worst from it and some people got better from it.
Should You Eat Fish?
This is also a very controversial topic. There are studies that eating fish may slow the onset of dementia. So there are some benefits to fish. But unfortunately, all seafood is contaminated with mercury to a certain extent. While some (see podcast linked here) believe eating fish is safe. Others are not so sure (see video of Dr. Mercola intervieing Dr. Shade linked above).
Again the answer depends on your particular genetics and situation. Probably you shouldn’t eat too much fish. But if you do eat fish, eat the low mercury fish like salmon and sardines and avoid swordfish, tuna, and sea bass. If you don’t eat fish, you might want to consider supplement with a high quality fish oil for the DHA omega-3 fatty acid which is hardly found elsewhere in foods.
Personally, I take the middle road. I do eat fish, but only once in a while. And I do take fish oil supplement, but only once in while.