Abstract
In this paper, I introduce the concept of depression-dementia medius, presenting the last days of Franz Joseph Haydn as an example. Haydn was a famous classical composer who spent most of his life as a court musician for the Esterházy family and composed some 700 works. This demanding work in the court was achieved under conditions of high psychological tension (P. Janet), and after Haydn completed the first two movements of his last string quartet, op.103, in 1803, he could no longer compose. At that time his psychological health declined, possibly due to exhaustion after lengthy creative work. Haydn retired to his house in Vienna, cared for by his familiar servants and sometimes evidenced depressive moods or cognitive impairment. It is likely that he developed subcortical vascular encephalopathy, but he did not critically develop depression nor dementia. His innate higher psychological tension and familiar circumstances kept him in a state of depression-dementia medius.