Dissociative identity disorder (DID) is a mental health condition. People with DID have two or more separate identities. These personalities (called alters) control their behavior at different times. The identities might have different genders, ethnicities, interests and ways of interacting with their environments. DID can lead to gaps in memory and hallucinations.

Dissociative identity disorder can develop in response to severe, repeated trauma during early childhood. Common causes include physical, sexual, and emotional abuse, as well as neglect, natural disasters, war, and other traumatic events. If such experiences occur before the personality fully forms (typically before age 9), the identity can fragment—dividing traits and emotions into separate parts, some of which remain hidden until a safe space allows them to emerge.

Particular identities may emerge in specific circumstances. Transitions from one identity to another are often triggered by emotional stress. Some alters often take on the role of “a protector,” shielding the individual from emotional pain or danger.
The ‘‘host’’ or the ‘‘core identity’’ of a DID system often initially has no awareness of their trauma from the past. Once starting therapy, receiving a diagnosis, or becoming familiar with the condition, a person with this disorder starts to recognize the signs of switching, other alters and recover some traumatic memories.

• It’s a coping mechanism.
• The disorder affects between 0.01 and 1% of the population. It can occur at any age. Women are diagnosed with DID more frequently than men.
• According to some studies DID is more common than young women with bulimia.
• Contrary to popular belief, survivors with DID are not more dangerous than the general public. The crime rate, violent use of weapons, domestic disturbances, etc. are no greater than (and often less than) the general population.
• The average number of personalities in a DID system is 10. Some alters play specific roles in the person’s life for many years.