Harvard Psychology Textbook (post 2) calls multiple personality disorder “rare” at .5% to 1% of the general population (1.5 to 3 million cases in USA, 35 to 70 million worldwide)

“Prior to 1970, DID [dissociative identity disorder] was considered rare, with only about 100 cases reported in the professional literature worldwide. However, since that time, the number of reported cases grew enormously until the late 1990s—and then oddly shrank again. Recent estimates are that between .5% and 1% of the general population suffers from the disorder…The strange transition of DID—from a rare disorder to a minor epidemic and back again—has raised concerns that the disorder is a matter of faking or fashion” (1, p. 572).

Yes, you read the above correctly: “from a rare disorder to a minor epidemic and back again.” That equates 100 cases worldwide with .5%—1% of the general population. And if we take the more conservative figure, 0.5%, and if the USA has about 300,000,000 people and there are about 7,000,000,000 people worldwide, that means 1,500,000 people in the USA and 35,000,000 people worldwide are estimated to have multiple personality disorder.

And that is only the disorder, multiple personality disorder: 1.5 million in the USA and 35 million worldwide are conservative estimates of the number of people who have the disorder, meaning that they have distress and/or dysfunction from their multiple personality.

But just as there are many more people who have anxiety than have an anxiety disorder, there are many more people who have multiple personality than have multiple personality disorder. This blog is not about the disorder. It is about normal multiple personality, as exemplified by novelists.

1. Daniel L. Schacter, Daniel T. Gilbert, Daniel M. Wegner. Psychology, Second Edition. New York, Worth Publishers, 2011.