D.I.D., or Dissociative Identity Disorder, is the new term for the condition many people know better as Multiple Personality Disorder. It is a trauma-born mental health condition characterized by the existence of multiple distinct personality states within one human body. These distinct personality states can have different names, likes, dislikes, speaking styles, appearance preferences, life outlooks, goals, motives, and even physical abilities than the “host” personality (the personality that is most present in day-to-day life.)

Dissociative disorders exist on a spectrum, much like how we have come to understand gender and sexuality existing on a spectrum. On the far left-hand side of the spectrum, there is “normal” dissociation, which is what we colloquially refer to as “being on autopilot”. This is what you experience when you arrive to work and realize that you don’t remember any of your commute. On the far right-hand side of the spectrum, there is full-fledged D.I.D., which is what we colloquially refer to as “a zebra that looks sort of like a horse”. I’ll get back to that metaphor in a minute.

Some people have dissociative disorders that don’t meet full diagnostic criteria for D.I.D., such as depersonalization/derealization disorder or the blandly named D.D.N.O.S., which stands for Dissociative Disorder Not Otherwise Specified. Some people try to diminish their or other people’s experiences by using the label of D.D.N.O.S., implying that there is some kind of hierarchy to the validity of dissociative disorders. Those people are wrong. Clinically, from about the halfway point of the dissociative disorder spectrum all the way over to the far right-hand corner, all dissociative disorders are treated the same: talk therapy focusing around resolving traumatic experiences, and sometimes medication for symptom management.

Back to the zebra thing. D.I.D. is super rare, but it is also (in my humble opinion) massively underdiagnosed. There is another saying: if you are a hammer, everything looks like a nail. If you are a DBT therapist, D.I.D. can look like borderline. If you are a psychiatrist, D.I.D. can look like bipolar or psychosis. And if you are the public in general, if a person doesn’t like look Sybil, you won’t suspect D.I.D. and you may not even believe a person who tells you that they have it. The saying I’m referencing with my zebra metaphor is “when you hear hoofbeats, think of horses, not zebras.” This is great clinical practice, until you find you have incorrectly treated a zebra as a horse for years and actually did more damage to them in the process.

Obviously, if I could sum up everything I know about D.I.D. into a single post, I wouldn’t be writing this blog. There would be no need. But I think these are some of the most important points, and I hope they give you a good background from which to read the rest of this blog.