In recent years, some therapists, psychologists, and other professionals have displayed skepticism towards the credibility of multiple personality disorder (MPD), or what is presently known as dissociative identity disorder (DID).  With the recent rise in diagnoses of dissociative identity disorder, and also the rise in the number of alters, or personalities these individuals are possessing, professionals have been skeptical of the disorder, and being even more extreme, proclaiming that there is no such mental illness as DID (Goff, 1993). These critics argue that environmental variables, or social influences, such as the media, and that the fluctuation of the therapeutic process play large factors in the diagnosis and treatment of the disorder (Spanos, 1994).
                 Much controversy has recently risen over dissociative identity disorder, due to this rise of diagnoses and alters, changes in the therapeutic process, and societal influence (Spanos, 1994).  One way to address this controversy, would be to examine past cases of DID, formerly known as multiple personality disorder, and compare and contrast them with recent cases of the disorder.  An historical case study of Mary Reynolds, the first person believed to be diagnosed with multiple personality disorder, will be used to compare and contrast.  The main areas of the disorder, such as the onset, structure, symptoms, and pattern, will be the primary focus of the comparison to conclude if the disorder has been consistent over time.  Mary Reynolds's case is an adequate sample due to her birth date,1785, and her date of diagnosis, 1810.  This is a time period where multiple personality disorder was unheard of, and societal influences such as mass media and psychological therapy had not yet been created.  This now allows an accurate comparison between the case of Mary Reynolds and present cases to be depicted.  Therefore, it could lend evidence that if the onset, structure, symptoms, and pattern are consistent with recent cases, and keeping in mind that the variables causing present controversy could not have influence due to their non-existence,  this would suggest that the disorder is credible and therefore exists.