Does it matter if it's just temporary? If it works, it is the smoking gun of what alzheimers is and why it happens. If it is not a permanent fix, the next question is what is happening in the body that is causing these blockages. It also means that microplastics may be a leading cause.

Most likely the build up of those beta amyloid is faster than what the brain can clear by itself. The drainage likely just reduced the amyloid significant enough for the brain to recover. This is likely more of physics explanation than biological. It is similar cleaning the wound by itself has spectacular effect for recovery than you leave it cluttered with dirt and pus.