What possible medical explanations have been offered for Friedrich Nietzsche’s mental collapse?

Following his mental collapse in Turin in 1889, Friedrich Nietzsche spent the final decade of his life in a state of total mental incapacity. Several medical explanations have been proposed by scholars and historians to account for his breakdown:12

• Tertiary Syphilis: For many years, the prevailing diagnosis was that Nietzsche suffered from atypical general paralysis caused by dormant tertiary syphilis.2
• Retro-orbital Meningioma: Another prominent theory suggests he suffered from a retro-orbital meningioma, a tumor located on the brain's meninges behind his right eye.12
• Cerebral Vascular Issues: Some later medical analyses have pointed to the degeneration of his cerebral blood vessels as a potential cause for his decline.2

These theories attempt to explain the severe health struggles that plagued him throughout his adult life, which included chronic migraines, vision problems, and vomiting, eventually forcing his retirement from teaching in 1879.1