According to the German website Politically Incorrect, Dr. Armin Geus, emeritus professor of medical history at the University of Marburg, who wrote a book exploring the possibility that Mohammed, the supposed founder of Islam, had been suffering from a mental illness, is now under investigation for "Incitement to hatred against peoples" and "Insulting faiths, religious communities and philosophical associations". The investigation was prompted by a complaint filed by the Saudi-controlled Wahhabist centre, the King Fahd Academy.
The professor's book "Die Krankheit des Propheten" [The Illness of the Prophet] (ISBN 978-3-941365-15-5) came to the conclusion that Mohammed suffered from paranoid-hallucinatory schizophrenia. I haven't read the book, but Geus is a serious academic, recognised in his field. The question of whether Mohammed suffered from a mental illness should be a legitimate subject for scientific inquiry. But not where Muslims, and their apologists, hold sway. Where Islam spreads, freedom dies.