OSDD1-OSDD1a-OSDD1b: The Differences

The Differences Between OSDD-1, OSDD-1a and OSDD-1b

OSDD-1:

Is the subtype that is most similar to Dissociative Identity Disorder (DID).

It is used for individuals who have similar symptoms to those with DID but who do not meet the full diagnostic criteria for DID. Most commonly, this describes individuals who have dissociative parts that are not sufficiently differentiated to qualify as alters (sometimes known as OSDD-1a) or individuals who do not have amnesia between alters (sometimes known as OSDD-1b).

Some individuals with OSDD-1 lack both amnesia and highly distinct parts, and other individuals with OSDD-1 have highly distinct parts but rarely or never switch between them. These latter cases are also sometimes described as OSDD-1b.

OSDD-1a:

Is unique but difficult to diagnose because there is no clear boundary that determines if a part is associated with sufficient “discontinuities in sense of self and agency” to warrant a diagnosis of DID.

A general rule of thumb is that if an individual has inter-identity amnesia, DID is diagnosed if there are two or more parts that each have an independent sense of self and self history.

Indications that parts have an independent sense of self can include parts presenting with their own names, genders, sexualities, or other identity traits or parts having internal communication and relationships with each other.

For individuals with OSDD-1a, dissociated parts are more likely to present as the same individual at different ages, as the same individual in different modes, or as different versions of the same individual.

The individual may go by the same name regardless of which part is present, and each part may view itself as the main part. However, parts may still have different skills, emotional reactivity, or ways of interacting with the world.

Additionally, because these parts lack full awareness of each other and each others’ activities, they may express themselves in highly contradictory ways.

For example, someone with OSDD-1a may have a work self, a family self, a 5 year old self, and an angry self in addition to several parts that hold trauma memories.

The work self may fully believe that work always needs to come first while the family self always prioritises family, and these parts may become confused or agitated when others point out inconsistencies in their behaviour or stated beliefs.

OSDD-1b:

Is one of five diagnostic labels clinically recognised to cause a system along with DID, OSDD-1 and OSDD-1a.

It is a sub-type of Other Specified Dissociative Disorder type 1, where the members of the system are differentiated from each other but do not experience amnesia of events between the members. They may, however, experience emotional amnesia - remembering the event that happened, but not the associated emotion.

Due to being fairly differentiated, the different members of the system may also have different emotional attachments to events due to simply having different personalities.

Due to the way the disorder functions, systems with OSDD-1b may have a difficult time coping with their trauma because they cannot subconsciously escape from knowledge of it like those with DID and OSDD-1a can. They may also struggle with accepting their system because not losing memory makes them feel like they're always the same person, or not losing memory can make it feel like their system is out of control.

Read about alter roles here
Read about DID here

Read about how to support your SO/partner with DID here

*these posts are also helpful for OSDD systems*