Which disorder is characterized by two or more distinct personality states?

Dissociative Identity Disorder (DID) is characterized by the presence of two or more distinct personality states, often referred to as "alters." Each alter may have its own name, age, history, and characteristics. Individuals with DID often experience gaps in memory regarding everyday events or personal information, which is a key aspect of the disorder. This fragmentation of identity usually arises as a coping mechanism in response to traumatic events, often during childhood.

Understanding DID is crucial because it highlights the complexities of human identity and the ways in which trauma can affect psychological functioning. This disorder is distinct from other conditions, such as schizophrenia, which does not involve multiple personalities but rather symptoms like delusions or hallucinations. Borderline Personality Disorder is characterized by instability in moods, behavior, self-image, and functioning, but does not involve distinct identities. Post-Traumatic Stress Disorder (PTSD) is related to experiencing severe trauma and can include flashbacks and avoidance behaviors, but it does not involve the presence of multiple distinct personality states. Thus, the clarity of DID's defining feature of multiple identities sets it apart from these other disorders.