major depressive disorder. Other specified depressive disorder in individuals with dissocia- tive identity disorder often has an important feature: the depressed mood and cognitionsﬂuc- tuate because they are experienced in some identity states but not others.
Bipolar disorders. Individuals with dissociative identity disorder are often misdiag- nosed with a bipolar disorder, most often bipolar II disorder. The relatively rapid shifts in mood in individuals with this disorder—typically within minutes or hours, in contrast to the slower mood changes typically seen in individuals with bipolar disorders—are due to the rapid, subjective shifts in mood commonly reported across dissociative states, some- times accompanied by ﬂuctuation in levels of activation. Furthermore, in dissociative identity disorder, elevated or depressed mood may be displayed in conjunction with overt identities, so one or the other mood may predominate for a relatively long period of time (often for days) or may shift within minutes.
Posttraumatic stress disorder. Some traumatized individuals have both posttraumatic stress disorder (PTSD) and dissociative identity disorder. Accordingly, it is crucial to dis- tinguish between individuals with PTSD only and individuals who have both PTSD and dissociative identity disorder. This differential diagnosis requires that the clinician estab- lish the presence or absence of dissociative symptoms that are not characteristic of acute stress disorder or PTSD. Some individuals with PTSD manifest dissociative symptoms that also occur in dissociative identity disorder: 1) amnesia for some aspects of trauma, 2) dis- sociative ﬂashbacks (i.e., reliving of the trauma, with reduced awareness of one’s current orientation), and 3) symptoms of intrusion and avoidance, negative alterations in cogni- tion and mood, and hyperarousal that are focused around the traumatic event. On the other hand, individuals with dissociative identity disorder manifest dissociative symptoms that are not a manifestation of PTSD: 1) amnesias for many everyday (i.e., nontraumatic) events, 2) dissociative ﬂashbacks that may be followed by amnesia for the content of the ﬂashback, 3) disruptive intrusions (unrelated to traumatic material) by dissociated identity states into the individual’s sense of self and agency, and 4) infrequent, full-blown changes among different identity states.
Psychotic disorders. Dissociative identity disorder may be confused with schizophre- nia or other psychotic disorders. The personified, internally communicative inner voices of dissociative identity disorder, especially of a child (e.g., ”I hear a little girl crying in a closet and an angry man yelling at her"), may be mistaken for psychotic hallucinations.
Dissociative experiences of identity fragmentation or possession, and of perceived loss of control over thoughts, feelings, impulses, and acts, may be confused with signs of formal thought disorder, such as thought insertion or withdrawal. Individuals with dissociative identity disorder may also report visual, tactile, olfactory, gustatory, and somatic halluci- nations, which are usually related to posttraumatic and dissociative factors, such as partial ﬂashbacks. Individuals with dissociative identity disorder experience these symptoms as caused by alternate identities, do not have delusional explanations for the phenomena, and often describe the symptoms in a personified way (e.g., ”I feel like someone else wants to cry with my eyes”). Persecutory and derogatory internal voices in dissociative identity disorder associated with depressive symptoms may be misdiagnosed as major depression with psychotic features. Chaotic identity change and acute intrusions that disrupt thought processes may be distinguished from brief psychotic disorder by the predominance of dis- sociative symptoms and amnesia for the episode, and diagnostic evaluation after cessation of the crisis can help confirm the diagnosis.