It is tragically funny to consider linking quietness of mind with LSD. It is everything but quiet

The "neuroplasticity" which leads to a relative quietness presumably comes after the psychedelic experience.

Interestingly, the paper only lists the following adverse effects: visual perceptual changes, nausea, and headache. Given that the patients in the double-blind study were those who suffer from moderate to severe Generalized Anxiety Disorder, I could imagine some significant anxiety in the 200 µg active group!

The paper only reports significant results at the 100 µg and 200 µg dose level, not less, which seems like another strike against psychedelic microdosing. The pharmaceutical industry would love to find a magic psychedelic drug which doesn't result in the psychedelic experience, but it seems like that experience is the key to their mental impact.