Dissociative Amnesia is defined by an inability to recall important autobiographical information, usually of a traumatic or stressful nature, that is inconsistent with ordinary forgetting. Depersonalization/Derealization Disorder is defined by persistent or recurrent experiences of depersonalization (detachment from, or feeling like an outside observer of, one's own thoughts, feelings, body, or actions) and/or derealization (a sense of unreality or detachment from one's surroundings) -- with intact reality testing and no memory loss.
Dissociative Amnesia's onset is typically tied to a specific traumatic or highly stressful event, with the memory gap emerging around that event. Depersonalization/Derealization Disorder's onset can be gradual or sudden, and while it may follow significant stress, it is not defined by a specific memory-related trigger event.
Dissociative Amnesia's duration varies -- the memory gap may resolve or may become chronic, and can present as localized, selective, generalized, or systematized amnesia. Depersonalization/Derealization Disorder requires the depersonalization/derealization experiences to be persistent or recurrent, which can present as brief episodes or continuous states.
Dissociative Amnesia's hallmark is a genuine, clinically significant gap in autobiographical memory -- the person cannot recall information they would ordinarily be expected to retain. Depersonalization/Derealization Disorder specifically preserves memory and reality testing -- the person remains aware that their altered sense of self or surroundings is not objectively real, and does not lose access to autobiographical information.
Dissociative Amnesia's impairment stems from the practical and relational consequences of the memory gap itself, and in cases of dissociative fugue, can include disorientation about identity or purposeful travel with no memory of it. Depersonalization/Derealization Disorder's impairment stems from the distressing, often frightening quality of feeling detached from oneself or one's surroundings, despite intact memory and reality testing.
Dissociative Amnesia requires ruling out substance effects, a neurological or other medical condition, and other dissociative, trauma-related, or neurocognitive disorders as the cause of the memory disturbance. Depersonalization/Derealization Disorder requires ruling out substance effects, another medical condition, and that the experiences are not better explained by another mental disorder such as schizophrenia, panic disorder, or major depressive disorder.
The deciding feature is whether autobiographical memory is actually lost. When a person cannot recall important personal information inconsistent with ordinary forgetting, Dissociative Amnesia applies. When memory is intact but the person experiences persistent or recurrent detachment from their own mind, body, or surroundings while reality testing remains intact, Depersonalization/Derealization Disorder applies.
Both disorders can be described by patients as feeling 'disconnected' from themselves, which can blur the distinction in casual conversation, but the presence or absence of an actual memory gap is the decisive clinical feature -- depersonalization/derealization does not involve losing access to autobiographical information, however unreal it feels.
After surviving a violent assault, a person is unable to recall several hours surrounding the event, a gap inconsistent with ordinary forgetting -- Dissociative Amnesia. A person repeatedly feels as though she is watching herself from outside her body, with a persistent sense that her surroundings are unreal, while retaining full memory of her life and clear awareness that these feelings are not objectively true -- Depersonalization/Derealization Disorder.
| Feature | Dissociative Amnesia | Depersonalization/Derealization Disorder |
|---|---|---|
| Memory | A genuine, clinically significant gap in autobiographical memory | Fully intact; no memory loss |
| Core experience | Inability to recall important personal information | Persistent/recurrent detachment from self, body, or surroundings |
| Reality testing | Not specifically about reality testing | Explicitly intact -- the person knows the detachment isn't objectively real |
An inability to recall important autobiographical information, usually of a traumatic or stressful nature, that is inconsistent with ordinary forgetting and not attributable to a substance or a neurological/medical condition; may include a specifier for dissociative fugue, involving apparently purposeful travel or bewildered wandering associated with amnesia for identity or other important autobiographical information.
Persistent or recurrent experiences of depersonalization (detachment from one's own thoughts, feelings, body, or actions, as if an outside observer) and/or derealization (detachment from surroundings, as if the world is unreal or dreamlike), with intact reality testing throughout.