The aluminum relations are easily explained with the observation that healthy kidneys excrete aluminum well, whereas unhealthy kidneys don't and so it accumulates. There might also be similar variations in aluminum deposition in the brain depending on the brain's innate ability to wash out chemicals. In contrast, the excretory mechanisms of plastics seems less trustworthy.

The user is deliberately and blatantly ignoring a wealth of scientific literature that exists. Also, plastics come bundled with numerous other harmful classes of chemicals, e.g. phthalates, bisphenols, etc. The risk is not merely in the brain, but also in blood vessels, including those adjacent to the heart.

Beware the plastics industry shills on this page. They will have you ignore the science, become infertile, and then have you die, all for their temporary gain.

It doesn't change the fact that there is no actual causal evidence. Perhaps the demented brains simply suck at flushing out microplastics as well. If you ever find people with more microplastics exposure have more dementia (like they did for asbestos and lung cancer), then you're onto something. But no rigorous study has found this yet. And if they do, you will hear of it immediately for sure, given how much reporting there is for microplastics=bad for you.