Dissociative Identity Disorder (DID) was formerly known as Multiple Personality Disorder (MPD) before the diagnostic name change. The term "Multiple Personality Disorder" was used in the DSM-III (Diagnostic and Statistical Manual of Mental Disorders, Third Edition), published in 1980. The name was changed to Dissociative Identity Disorder in the DSM-IV, which was published in 1994.
The change in diagnostic terminology was made to reflect a better understanding of the condition and to reduce misunderstandings and stigma associated with the term "multiple personality," which some people found misleading or sensationalized.
It's important to understand that the change in diagnostic name does not imply that the condition itself has changed, but rather reflects an evolution in the understanding and classification of dissociative disorders. The criteria for diagnosing DID remained essentially the same in both DSM-III (MPD) and DSM-IV (DID).
Since the publication of the DSM-IV, the diagnosis of Dissociative Identity Disorder (DID) has continued to be used to describe the same clinical condition involving the presence of two or more distinct identities or personality states, along with gaps in memory that can't be explained by ordinary forgetfulness. The DSM-5, published in 2013, also retains the diagnosis of DID.
It's essential to use the current diagnostic terminology (Dissociative Identity Disorder) to ensure accurate communication and understanding within the mental health community.