1) Were there any prevalent theories about the connection between mental illness and pain and/or trauma in the mid-19th century? As far as I know shell shock (let alone PTSD) weren't recognized until in the 20th century, but I'd suppose the connection was at least at some level understood. (It doesn't really matter whether the hypothetical theory links insanity with pain or trauma, because the character has experienced both.)
I've googled with combinations of search terms such as 'causes', 'insanity', 'victorian', 19th century' and also browsed through Journal of Victorian Studies, but it seems that alcoholism and masturbation were so popular reasons that they just come up everywhere. However, I have found some tables where the causes of insanity of the patients in a particular asylum have been listed, but they haven't really helped though sometimes physical illnesses are mentioned.
2) The second question is not so much tied to the time period, but the story I need this information for takes place in Vienna in the first half of the 19th century. Would it be possible / how difficult would it be to take a pianoforte or clavichord that has been built in the late 18th century, and replace its mechanism with one that was fashionable in around 1840's? Would the outer measurements or features be too different? I know that in the late 18th century, during the transformation from harpsichord/clavichord to pianoforte, such actions were sometimes made, but in those cases the outer and inner part of the instrument were made almost at the same time.
I really don't know how to google this one, but I have read about old piano manufacturers and browsed through a journal called Early Music, which provided lots of useful information but did not answer this question.
Thanks a lot in advance!