What was the reason for Joseph Haydn's mental decline and gait disturbance? A case of subcortical vascular encephalopathy in the early 19th century

For most of his life, Joseph Haydn (1732-1809) was a healthy man, apart from a chronic nasal polyp. With increasing age, Haydn is said to have suffered from progressive forgetfulness which prevented him from composing for about the last 8 years of his life. He spent his days immobilized and inactive, suffering from frequent leg swelling, which has commonly been regarded as the reason for Haydn's gait disturbance. Most biographers quote diffuse atherosclerosis and congestive heart failure as the diagnosis of the composer's final illness and a reason for his death. A more sophisticated pathography, however, can be inferred from a detailed analysis of documents and sources, which leads to a diagnosis of subcortical vascular encephalopathy. This is a variant of cerebral microangiopathy with a classical triad of sequential symptoms: a dyspraxic gait disturbance (i.e. frontal gait apraxia), neuropsychological 'frontal lobe' deficits (i.e. cognitive slowing and amnestic deficits leading to an abulic syndrome and slowly progressive dementia, and mood disorders of various degrees (i.e. depression, lability of affect, abnormal crying and laughing). All three components can be documented from Haydn's biographies. In the classical descriptions of the composer's contemporaries Dies, Carpani and Griesinger - despite his legs being swollen in various degrees as a symptom of congestive heart failure - there are clues for a severe dyspraxic gait disturbance contrasting with initially preserved but progressively deteriorating bimanual motor interaction, which eventually led to Haydn's complete immobilization.