Dissociative identity disorder is currently a recognized psychiatric diagnosis and is more commonly known as split personality disorder. The symptoms of this disorder is having more than one distinct set of beliefs, attitudes, and mannerisms without the realization that the other set exists. People with this disorder also show marked loss of memory and great distortion of time (they may not remember recent events). In the last 10 years there has been an increase in the number of people getting this diagnosis. Despite this, there is a lot of active debate in the psychiatric field as to the actual prevalence of dissociative identity disorder. Many experts believe that in its purest form, is probably very rare.
It sounds like your sister does warrant evaluation by a psychiatrist
. You have stated that she seems depressed, and she may require treatment for this. People with depression
can have wild mood swings which can appear like changes in their personalities. While it is possible that your sister does have dissociative identity disorder, statistically she is much more likely to have pure depression with or without an overlying personality disorder. To answer your question directly, there is not category of diagnoses where a person with dissociative identity disorder receives individual diagnoses for each personality. As her sister, I would encourage her to see a qualified psychiatrist sooner than later. Good luck.