What caused Nietzsche's insanity and death?

What caused Nietzsche’s insanity and death?:
A paper just published in Acta Psychiatrica Scandinavica reconsiders the insanity and death of philosopher Friedrich Nietzsche, who is commonly thought to have died of neurosyphilis.

In contrast, the authors of the new study suggest that Nietzsche died of frontotemporal dementia – a type of dementia that specifically affects the frontal and temporal lobes.

While many people have ‘diagnosed’ historical figures in retrospect, this study is different, in that the authors reviewed Nietzsche’s actual medical notes in light of what is known about the progression of syphilis and dementia today.
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i think it was the opera.