from der Spiegel in 2014...
"Many historians have refrained from questioning the conclusion that the king from the House of Wittelsbach was mentally ill. After all, Ludwig gave his contemporaries ample reasons to question his sanity. He plunged his kingdom into massive debt with his megalomaniac construction projects. And he countered warnings that he wouldn't be permitted to complete ongoing construction projects by threatening to commit suicide.Mannheim-based psychiatrist Heinz Häfner notes thatLudwig was hard-working, contrary to his reputation. Each year, his majesty reviewed 800 documents pertaining solely to domestic Bavarian affairs. A few days before he was dethroned, the king had worked his way through a pile of papers which he signed and sent to the relevant ministries. Ludwig conducted government business far more quickly than his predecessor Maximilian II, Häfner remarked."
But the same magazine reports this week (in German) that a newly discovered letter adds credence to the doubts.
"How can such an infamy be possible!" 'Der Kini' wrote on the 10th of June 1886, complaining of a conspiracy against him. The letter came to light only recently and will account for much rejoicing in the Bavairian royalist camp.