Where to begin! Given that he lived before the ideal of mental illness was recognised, it’s realistically impossible to say. Certainly, he was considered “odd” by the standards of the time and I wouldn’t be at all surprised if he was on the Autism spectrum given he reportedly suffered from suffered from scrupulosity but that’s just amateur speculation. If nothing else, his affliction drew his closer to God since he undoubtedly knew more than most his need for divine help and grace.