I'm not much help to you because I am slowly increasing, not decreasing.
I have noticed during an increase from 6mg. to 8mg., I feel drowsy. I had been taking Abilify in the AM; however, I am now trying it in the PM in hopes of avoiding AM drowsiness. (The drowsiness had lasted until noon or 1 pm, while taking it in the AM.)
I may increase it more. It depends. I am looking for an "activating" effect. I want to increase relatively slowly, in order to possibly find the least amount that may do the trick.
I hope others come along and reply. This post had quickly made it to page #3. Posts move along rather quickly.
As always, my best to you!

WC