Despite the occasional lucid episode, Friedrich Nietzsche never regained his sanity and his visitors seldom stayed long. His growing fame inspired renewed curiosity about the ailing genius but Franziska limted all access. Caring for her invalid son must have been a tremendous burden for Franziska and she was only seventy-one when she died on April 20, 1897. Afterward, her daughter, Elizabeth. became Friedrich Nietzsche's new caregiver. Having already gained control over her brother's estate and all of his writings, Elizabeth moved her brother to Villa Silberblick near the city of Weimar. The large villa also housed the Nietzsche Archives, carefully maintained by Elizabeth (she was also his literary executor) and is still a major pilgrimage site by Nietzsche's admirers. He and Elizabeth lived there until his death on August 25, 1900 at the age of fifty-five. In a move which would have appalled the self-styled "Antichrist", Elizabeth had him buried with a traditional Lutheran funeral with a church choir and a coffin bearing a silver cross.
Along with his numerous books and philosophical writings, Friedrich Wilhelm Nietzsche also left behind a medical mystery. What was the illness which struck him down when he was at the height of his intellectual powers? Although neurosyphilis is the most commonly accepted diagnosis, there was no real evidence to support it. Reliable tests for syphilis didn't exist in Nietzsche's lifetime but it was still common practice for autopsies to examine the brains of suspected syphilis cases for the tell-tale lesions that might confirm the diagnosis. Not only was this not done in Nietzsche's case, Elizabeth would later state that she had been unaware of the "disgusting accusation" of her brother's syphilis. As rumours grew about the cause of Nietzsche's mental breakdown, she recruited neurologist Paul Julius Mobius to review all available medical records. A prolific science writer and researcher who is best known today for giving his name to Mobius syndrome, Mobius examined all the medical notes by Nietzsche's doctors at Basel and Jena and concluded that the syphilis diagnosis was correct. He also dismissed questions about the atypical nature of Nietzsche's illness by stressing how variable the disease could be. This despite the fact that Nietzsche surviving nineteen years following the initial diagnosis was virtually unprecedented in true syphilis patients (and he might well have survived longer given that he died of pneumonia). The book that Mobius later wrote about Nietzsche was hardly flattering and ended with the outrageous statement "Beware! This man has a diseased brain".
Suffice it to say, Elizabeth was not pleased and eventually wrote her own biography about her brother to refute Mobius' "vile insinuations". Desperate to preserve her brother's memory, Elizabeth's book portrayed him as being saintly and chaste (she included numerous testimonials from prominent Germans). Not being a medical doctor herself, she attributed his illness to drinking "Javanese tea" similar to cannabis. Medical experts were not impressed with her explanations and the syphilis explanation persisted for decades. Despite her distress over the lingering rumourse, Elizabeth Nietzsche carefully controlled her brother's legacy long after his death. She is also largely credited with promoting the "Nietzsche myth" concerning his life and writing and may not have been the best choice to act in that capacity given her own very, clear ideas on how her brother deserved to be remembered.
By the time of her own death in 1935, Elizabeth's support for Adolf Hitler ensured that her brother's philosophy would be permanently associated with the growing Nazi and Fascist movements (Adolf Hitler personally visited her in 1934 and had a photograph taken of him gazing reverently at a bust of Nietzsche). Even before the outbreak of World War 2, Nietzsche became known internationally as the "Nazi" philosopher with his "Ubermensch" ideas playing into Nazi propaganda. As a result, the notion of Nietzsche dying of syphilis became increasingly popular with anti-Nazi writers as a means of discrediting him. Neurologist Wilhelm Lange-Eichbaum was especially scathing in promoting the view that Nietzsche was to blame for Nazism and the resulting war. His books on Nietzsche probably did more to promote the syphilis story than any other source despite serious questions relating to the "evidence" of Nietzsche's syphilis that he presented (and which could never be confirmed by later reviewers).
But how plausible an explanation was it? Aside from his extremely long survival, there were additional details that made the syphilis diagnosis less likely. Even when Nietzsche was first examined in Jena, the attending physician noted some atypical medical signs including the lack of characteristic tremors normally associated with neurosyphilis cases as well as uneven pupil dilation. Based on Nietzsche's lifelong migraine headaches and his family history of stroke (which had killed his father at a relatively young age), more recent medical authorities have argued that Nietzsche's illness was likely due to an undiagnosed brain disease with various alternative diagnoses being suggested.
While a final determination of what caused Nietzsche's dementia will likely never be possible, this case represents a graphic example of how controversial some diagnoses can become. Especially when it can be used for propaganda purposes.