Background: Friedrich Nietzsche (1844-1900), one of the most profound and influential modem philosophers, suffered since his very childhood from severe migraine. At 44 he had a mental breakdown ending in a dementia with total physical dependence due to stroke. From the very beginning, Nietzsche's dementia was attributed to a neurosyphilitic infection. Recently, this tentative diagnosis has become controversial. Objective : To use historical accounts and original materials including correspondence, biographical data and medical papers to document the clinical characteristics of Nietzsche's illness and, by using this pathography, to discuss formerly proposed diagnoses and to provide and support a new diagnostic hypothesis. Materials: Original letters from Friedrich Nietzsche, descriptions by relatives and friends, and medical descriptions. Original German sources were investigated. Biographical papers published in medical journals were also consulted. Results : Nietzsche suffered from migraine without aura which started in his childhood. In the second half of his life he suffered from a psychiatric illness with depression. During his last years, a progressive cognitive decline evolved and ended in a profound dementia with stroke. He died from pneumonia in 1900. The family history includes a possible vascular-related mental illness in his father, who died from stroke at 36. Conclusions : Friedrich Nietzsche's disease consisted of migraine, psychiatric disturbances, cognitive decline with dementia, and stroke. Despite the prevalent opinion that neurosyphilis caused Nietzsche's illness, there is lack of evidence to support this diagnosis. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) accounts for all the signs and symptoms of Nietzsche's illness. This study adds new elements to the debate and controversy about Nietzsche's illness. We discuss former diagnoses, comment on the history of a diagnostic mistake, and integrate for the first time Nietzsche's medical problems.
