Funny enough, in the past days I was thinking about hoarding as a neurological disorder. It has similarities to keeping a lot of things in mind at the same time and re-iterate them over and over. The are quite a few mind-hoarders, as I call them, who basically hoard ideas and concepts to the point that they forget what is actually relevant here and now. Hoarding psychical objects might stem from the same cause inside the brain which causes the mind hoarding as well. Hence it can't be a psychological disorder alone.