What was the cause of Nietzsche’s dementia?


What caused Friedrich Nietzsche to collapse into insanity at the age of 44, when he was at the height of his creative powers? For most of the 20th century, the answer was: syphilis. In my paper titled “What was the cause of Nietzsche’s dementia?” published by the Journal of Medical Biography in 2003, I show that the diagnosis of syphilis doesn’t fit the facts of Nietzsche’s dementia. I explain how the diagnosis of syphilis was made, why that diagnosis persisted so long despite so much evidence to the contrary, and I suggest a more plausible alternative diagnosis. You can read the full text of my article at this link: http://www.leonardsax.com/Nietzsche.pdf.


I am honored that subsequent researchers have continued on this trail. The papers cited below all agree that the medical evidence in Nietzsche’s case makes the diagnosis of syphilis implausible, and the authors of each of these papers all cite my 2003 article. I have listed them below in chronological order, with a brief comment indicating the diagnosis favored by those researchers. One group of neurosurgeons (Owen, Schaller, and Binder) concur that a frontal meningioma is the most likely diagnosis. Other researchers argue for other explanations. The one point on which all these researchers agree is that the diagnosis of syphilis is contradicted by the facts of Nietzsche’s case.

M. Orth & M. R. Trimble (2006). Friedrich Nietzsche’s mental illness – general paralysis of the insane vs. frontotemporal dementia. Acta Psychiatrica Scandinavica volume 114, pp. 439-444. These neurologists argue make the case for frontotemporal dementia, rather than syphilis.

Christopher Owen, Carlo Schaller, and Devin Binder (2007). The madness of Dionysus: a neurosurgical perspective on Friedrich Nietzsche. Neurosurgery volume 61, pp. 626-632. These neurosurgeons argue for a right-sided meningioma, as I did.


D. Hemelsoet, K. Hemelsoet and D. Devreese (2008). The neurological illness of Friedrich Nietzsche. Acta Neurologica Belgica, volume 108, pp. 9-16. This collaboration between a neurologist and two professors of German yielded the diagnosis of CADASIL: Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy.

Christiane Koszka (2009). Friedrich Nietzsche: A classical case of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome? Journal of Medical Biography volume 17, pp. 161-164. This biochemist makes the case for MELAS.

Helen Danesh-Meyer and Julian Young (2010). Friedrich Nietzsche and the seduction of Occam’s razor. Journal of Clinical Neuroscience, volume 17, pp. 966 – 969. These authors attribute Nietzsche’s dementia to underlying psychopathology.


Lampros Perogamvros and colleagues (2013). Friedrich Nietzsche and his illness. Journal of the History of the Neurosciences, volume 22, pp. 174 – 182. These authors agree with Hemelsoet, Hemelsoet and Devreese, that the most likely etiology was CADASIL: Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy.


Leonard Sax MD PhD

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