Ludwig II seemed to suffer from a severe form of bipolar-disorder, with extreme manic episodes (ie: his building mania and narcissism).
Elisabeth appears to have been unipolar-deppressive (no ups & downs like bipolar-disorder; just a constant, dull depression). it can develop at any point or can be inherited --- i inherited a chemical imbalance from my father that manifests itself as unipolar-depression. i also seem to share at least 2 other illnesses with her: obsessive-compulsive-disorder (aka: OCD) and severe social-anxiety-disorder.
her "mania" about her hair, her extreme devotion to excercise & her figure are typical of OCD compulsions; and her narcissistic "mania" about her beauty is a classic example of an OCD obsession. unfortunately, it's a short trip from those behaviors to anorexia, bulemia, body-dismorphic-disorder and several other illnesses that are more common today than they were in her time.
she also seems to have had something in common with Howard Hughes (another OCD sufferer): their extreme OCD behaviors appear to have been triggered by having been given sexually transmitted diseases by people they trusted. Sisi contracted an STD (i can't recall which one) from Franz Josef, and it completely destroyed her "knight in shining armor/prince-charming" view of him, as well as whatever sense of security she may have felt. very shortly thereafter, her wandering began.
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