Researching icons

Recently, I've decided to do some brushing up on my knowledge of some famous starlets by reading their biographies.  What I find to be really interesting is that the last four I have read up on had afflictions diagnosed later in their adult lives; Clara Bow and Bettie Page were both diagnosed with schizophrenia; Marilyn Monroe and Vivien Leigh were diagnosed with bipolar disorder.  I have to wonder if the affects of Hollywood exacerbated their conditions or if they had been masked due to the lifestyle they were living and showed up later. Hmmm.