Probably not, but some microplastic particles are only a nanometer in diameter. Many viruses (generally 30 to 100 nm in diameter) and some bacteria get across the BBB, but they can use transcytosis to do this. It wouldn't shock me if very small plastic microparticles can get across. Even if they don't get across, if they affect the brains microvasculature or the brain glymphatic system it could be bad. For me, I'd rather not have them there. Especially if they found an amount equivalent to a plastic spoon!
I have enough issues..
and they say the plastic can mimic estrogen? maybe your body is confused and it uptakes the particle. dunno