Just thought I should quickly mention that OCD is not just overt rituals. Plenty of OCD sufferers experience purely internal rituals and intrusive thoughts. So let me add to the question if I may: Is there any good documentation of internal religious experiences, like excessive and compulsive prayer or chanting, of people in relative seclusion (like a monastery) that could be analogous to a modern OCD, and perhaps is described by contemporary sourced as an actual problem for the sufferer?

To add, the question was inspired by a lecture on possible psycho-biological factors that might lead humans to develop religious thought, by Robert Sapolsky. Now, obviously, he's a biologist and not a historian, but he mentioned Martin Luther being quite probably obssesive, having written stuff like "No matter how much I wash, I cannot get clean" (paraphrasing). So I wonder if there are more probable cases and if they are indeed linked/attributed to religious devotion?