His father, also named Friedrich Wilhelm Hagen (1767–1837), was a noted clergyman.
[1] He worked as a medical practitioner in Velden, and in 1844 visited various mental institutions in England, France and Germany (Siegburg, Illenau, Heidelberg and Winnenthal).
In 1846 he began work at the district mental hospital in Erlangen as an assistant to Karl August von Solbrig, and three years later, was named director of the mental hospital at Kloster Irsee near Kaufbeuren.
On 8 June 1886, the four doctors unanimously ruled that Ludwig was most likely mentally unfit to govern.
Incredibly, up to that point in time, none of the four had ever personally examined the king as a patient.