Other Specified Dissociative Disorder
Other Specified Dissociative Disorder (OSDD) is a diagnosis in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR), and covers Partial Dissociative Identity Disorder (P-DID) in the International Classification of Diseases (ICD-11). This post details the different subtypes of OSDD according to the DSM-5-TR, and provides the ICD-11 equivalent.
OSDD is a dissociative disorder diagnosed when the patient has significant dissociative symptoms but doesn’t fit the criteria for any other dissociative disorder (that is, Dissociative Identity Disorder (DID), Depersonalisation / Derealisation Disorder (DP/DR), and Dissociative Amnesia). OSDD has four specifiers - type 1, which is equivalent to Partial DID in the ICD-11, type 2, 3 and 4.
OSDD type 1
OSDD 1 is perhaps the most well known of the Other Specified Dissociative Disorder types. In the DSM-5-TR, it’s called “Chronic and recurrent syndromes of mixed dissociative symptoms”, and gives the following description:
“This category includes identity disturbance associated with less-than-marked discontinuities in sense of self and agency, or alterations of identity or episodes of possession in an individual who reports no dissociative amnesia.”
Simply put, it’s DID but missing a symptom. The “less than marked discontinuities in sense of self and agency” part refers to someone who experiences DID but their alters aren’t fully elaborated or separate, which in DID communities is referred to as “OSDD 1a”.
The “alterations of identity or episodes of possession in an individual who reports no dissociative amnesia” part refers to someone who experiences DID without amnesia between alters. In DID communities this is called “OSDD 1b”.
(See this tumblr post on the differences between OSDD 1a and b).
In the ICD-11, OSDD 1 is a separate diagnosis called Partial DID (P-DID). It describes DID where only one alter is active in daily life with occasional switches or passive influence from other alters, usually fragments. This diagnosis covers OSDD 1b, but doesn’t account well for people with OSDD 1a. It also doesn’t account well for people with OSDD 1b who have well developed alters.
(See this tumblr post about Partial DID and OSDD.)
OSDD 1 is the only disorder other than DID that involves alters.
OSDD type 2
OSDD 2 is described in the DSM-5-TR as “identity disturbance due to prolonged and intense coercive persuasion”. A person with OSDD 2 has gone through some kind of experience that resulted in questioning their identity and sense of self. This could be torture, brainwashing, thought reform, political imprisonment, indoctrination, or involvement in a cult or terrorist organisation.
For example, an atheist adult who became involved in a religious cult eventually leaves, but is confused and distressed over their new religious beliefs.
OSDD type 3
OSDD 3 is a diagnosis given when a person experiences short term dissociation to a stressful or traumatic event. The dissociation doesn’t last longer than a month; if it did, the diagnosis would be changed to a different dissociative disorder (e.g. DP/DR).
OSDD type 4
OSDD 4 is a diagnosis given when a person experiences a dissociative trance. The dissociative trance can include involuntary movements or transient paralysis.
In the ICD-11, this is equivalent to Trance Disorder.