Wow, insanity, that must become an insanely long list
Let me see:
12. Les Uns et les Autres (1981, Bolero), Violin player ends up in asylum.
13. Un long dimanche de fiançailles (2004, A very long engagement), Audrey Tautou's shell shocked boyfriend ends up in an asylum.
14. À la folie... pas du tout (2002, He loves me...He loves me not), Audrey Tautou end up in an asylum herself.
15. Le Roi de Coeur (1966, King of Hearts), during WWI the lunatics are saner than the sane.
16. Persona (1966), actrice ends up in mental care
17. Såsom i en spegel (1961, Through a Glass Darkly), mentally ill woman is released
18. Wilderness (1996), Psychiatrist ends up in an institution after seeing a werewolf
19. Ginger Snaps: Unleashed (2004), sister of werewolf in asylum
20. Mr. Jones (1993), Richard Gere in asylum
21. Awakenings (1990), Robin Williams is doctor in mental hospital
22. The Pink Panther Strikes Again (1976), Inspecteur Dreyfuss escapes from asylum
23. Regeneration (1997), Wilfred Owen and Siegfried Sassoon meet in an asylum
24. Van de koele meren des doods (1982, Hedwig, the quiet lakes), Renée Soutendijk goes barmy.
25. Terminator 2: Judgment Day (1991), Linda Hamilton needs to be liberated from asylum
26. Prozac nation (2001), Christina Ricce gets treatment
27. Girl interrupted (1999), Winona Ryder and Angelina Jolie in asylum
so far...