I answered your questions based on what I gathered from wikipedia: > how do "the toxins" get out of the cerebro-spinal cavities It gets caught up in cerebrosp

I answered your questions based on what I gathered from wikipedia: > how do "the toxins" get out of the cerebro-spinal cavities It gets caught up in cerebrospinal fluid. Note sure if it is has to be properly dissolved in it or if it also transports mechanically. > if the flow is not unidirectional (with new fluid comming in), why would not the toxins just settle at slightly different place, after those fluid movements end Cerebrospinal fluid is constantly being created and then deposited to the blood stream. According to wikipedia you produce 500 mL a day and there is 125ml at any given time, so the cycling rate is pretty fast if we compare to how long Alzheimer takes to form. > how is the fluid itself cleaned It is extremely filtered blood, so it is basically cleaned blood. In other words it is cleaned in the creation step. > what about the blood-brain barrier Seems entirely unrelated, cerebrospinal fluid seems to be like its own circulation flow where blood doesn't reach. I guess it basically being a lot cleaner blood makes it another layer of protection for these parts of the brain. Source: https://en.wikipedia.org/wiki/Cerebrospinal_fluid##targetText=Cerebrospinal%20fluid%20(CSF)%20is%20a,absorbed%20in%20the%20arachnoid%20granulations https://en.wikipedia.org/wiki/Cerebrospinal_fluid##targetTex....