Introduction

Dissociative identity disorder (DID), previously known as multiple personality disorder, is a rare and complex psychiatric condition with an estimated population prevalence of approximately 1%.1 It is characterized by the presence of two or more distinct identity states, each with its own pattern of perceiving, relating to, and interacting with the world. Historically, dissociative disorders have occupied a contentious position in psychiatry, with critics questioning their scientific basis and clinical validity. As a consequence, the literature reports that affected individuals typically undergo 5 to 12.5 years of psychiatric treatment before receiving an accurate DID diagnosis.2 This diagnostic delay renders patients with dissociative disorders chronically underserved and exposes them to an elevated risk of adverse outcomes, including suicide.

Recent investigations have revealed a substantial convergence between DID and schizophrenia, including shared traumatic antecedents and overlapping neuroanatomical involvement.3 Despite being classified as distinct diagnostic entities, these disorders share considerable symptom overlap and implicate common neural structures, including the hippocampus, amygdala, and corticolimbic pathways. This overlap frequently results in diagnostic confusion, misdiagnosis, and suboptimal treatment. The present case report examines the intricate interplay between DID and psychosis within the context of a severe traumatic history, highlighting the diagnostic complexity and treatment implications of comorbid presentations. Table 1 provides a comparison of the diagnostic criteria for schizophrenia and DID.4

Table 1.Comparison of DSM-5 diagnostic criteria for schizophrenia and dissociative identity disorder
Schizophrenia Dissociative Identity Disorder
Two or more of: hallucinations, delusions, disorganized speech, disorganized/catatonic behavior, negative symptoms (≥1 must be hallucinations, delusions, or disorganized speech) Disruption of identity characterized by two or more distinct personality states, with recurrent gaps in recall of everyday events, personal information, or traumatic events
Continuous signs of disturbance for ≥6 months, with ≥1 month of active-phase symptoms Symptoms cause clinically significant distress or impairment; not attributable to substance use, medical condition, or cultural/religious practice
Social/occupational dysfunction; not better explained by schizoaffective, depressive, or bipolar disorder, substance use, or medical condition Notably absent: formal thought disorder (a key distinguishing feature from schizophrenia)

DSM-5 = Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition.

Case Description

A 28-year-old woman with a psychiatric history of depression and no significant past medical history was brought involuntarily to the emergency department under Florida’s Baker Act after law enforcement found her wandering in the street. She was claiming to be “Michael Jackson” and expressed a belief that someone was attempting to kill her because they had “purchased” her.

Upon arrival, the patient identified herself as a 16-year-old female with an alternate name; her true legal identity was subsequently confirmed through fingerprint analysis. She had been unhoused for an indeterminate period and disclosed an extensive history of physical and sexual abuse. On mental status examination, she was oriented to time and place but disoriented to person, unable to recognize her legal name or acknowledge her actual age. Her mood was euthymic, with blunted effects. Speech was slow and delayed. Thought process was disorganized, with evidence of thought blocking and prominent confusion. She was preoccupied with religious themes and endorsed auditory hallucinations as well as ideas of reference centered on “Jesus.” Delusions were present, both grandiose and persecutory in nature. Mild depressive symptoms were reported without active suicidal or homicidal ideation. The patient disclosed a history of coerced substance use; however, further biopsychosocial history was difficult to obtain, as she remained evasive, guarded, and internally preoccupied throughout the interview. Insight and judgment were severely impaired.

Neurological examination revealed no focal deficits. Laboratory workup was unremarkable except for an abnormal urinalysis, and empiric treatment for a urogenital infection was initiated. Urine toxicology was negative for substances of abuse, and neuroimaging demonstrated no acute intracranial pathology.

Given her poor response to multiple antipsychotic agents, treatment was initiated with clozapine, which was well tolerated and titrated to clinically therapeutic levels. However, due to psychosocial barriers limiting the patient’s ability to attend frequent outpatient visits for required hematologic monitoring, clozapine was cross-titrated to long-acting injectable haloperidol prior to discharge to facilitate adherence. Despite remaining guarded, the patient demonstrated meaningful improvement in her symptomatology over the course of hospitalization, including restoration of identity recognition.

Discussion

DID presents considerable diagnostic and clinical challenges due to its complex features and frequent symptom overlap with other psychiatric conditions, particularly psychotic disorders such as schizophrenia.1 Both disorders share a common contextual basis of childhood traumatic antecedents, and research has consistently highlighted the pivotal role of early trauma in the onset and expression of DID.1,2 At the same time, the prevalence of psychotic-like experiences among individuals with DID including hallucinations, ideas of reference, and paranoia can easily obscure the underlying dissociative pathology and contribute to misdiagnosis.

Psychosis encompasses a broad spectrum of symptoms, including hallucinations, delusions, and disorganized thinking, culminating in a profound detachment from reality. The co-occurrence of DID and psychotic symptoms has prompted ongoing investigation into shared underlying mechanisms. Neurobiological models suggest that alterations in brain structure and function particularly within the hippocampus, amygdala, and corticolimbic circuits. contribute to both disorders.3,5 An important distinguishing feature is the absence of formal thought disorder in DID, in contrast to schizophrenia, underscoring the necessity of careful and thorough differential diagnosis.1

While antipsychotic medications have historically been avoided in DID due to concerns about misdiagnosis and inadequate evidence, emerging data support a potential role for these agents in managing specific symptoms such as trauma-related paranoia and severe perceptual disturbances.1 In the present case, clozapine was selected given the patient’s lack of response to other antipsychotics, consistent with its established efficacy in treatment-resistant psychosis. The subsequent transition to long-acting injectable haloperidol reflected a pragmatic, patient-centered decision informed by her socioeconomic circumstances and the monitoring demands of clozapine therapy.

Emerging theoretical frameworks, including the network structure model of psychopathology, propose that dissociative and psychotic symptoms exist in intricate causal relationships with one another, rather than as discrete, categorically distinct entities.6 This perspective challenges traditional diagnostic boundaries and calls for a more nuanced, transdiagnostic approach to understanding and treating these comorbid presentations. Clinicians should remain vigilant for dissociative features in patients presenting with apparent psychosis, particularly in the setting of significant trauma histories, as failure to recognize DID may result in prolonged diagnostic delays, inadequate treatment, and preventable morbidity.

Conclusion

This case illustrates the diagnostic complexity inherent to DID and underscores the intersecting nature of dissociative and psychotic disorders when they co-occur in the context of severe trauma. Future research should further delineate the relationship between DID and schizophrenia, explore their bidirectional influence on one another, and critically examine the clinical utility of maintaining their categorical distinction within psychiatric nosology. Promoting awareness of these diagnostic challenges and expanding the evidence base for treatment can meaningfully reduce diagnostic delays and pave the way for more individualized and effective therapeutic strategies.