2 NAMES, 1 DISEASE: Does schizophrenia = psychotic bipolar disorder?

Box

Misdiagnosis of psychosis

Bipolar disorder can be missed when patients present with psychotic symptoms, but clinicians could have initially recognized Mr. C’s bipolar disorder. His diagnostic trail illustrates important points about psychotic presentations:

• Predominant psychotic symptoms can obscure mood disturbances.
  
• Mistakenly believing that psychosis means schizophrenia can jeopardize patient care.
  
• When paranoia and fear hide grandiosity, then mania—not schizophrenia—is likely.
  
• Psychotic mood disorders—not schizophrenia—cause functional psychosis; there is no schizophrenia (Box).
  
• Pursuing mood symptoms in psychotic presentations is critical in an initial diagnostic interview.
  

Questioning the concept that hallucinations, delusions, catatonia, and disorganization are specific to and diagnostic of schizophrenia is not new. In 1978, Pope and Lipinski compared symptoms, course, outcome, family history, and responses to lithium in bipolar disorder and schizophrenia.³ They and others find no symptom, group of symptoms, or course that differentiates schizophrenia from psychotic bipolar disorder.^{3-5,8,9,16,18,19} They conclude that most cases diagnosed as schizophrenia or schizoaffective disorder are misdiagnosed cases of bipolar illness, whereas others question the validity of schizophrenia.²⁰

Bipolar disorder has a broad spectrum of severity and course; it frequently reaches psychotic levels that can become chronic.^2,5,21 Psychotic symptoms of rigorously diagnosed bipolar patients can deteriorate until their overwhelming psychosis obscures bipolar symptoms.^5,6,13,21 Like most, if not all, acutely psychotic bipolar patients, Mr. C shows all diagnostic criteria for schizophrenia.^1-6,21

Patients with severe, psychotic bipolar disorder can stop responding to medication and suffer chronic deterioration without remission.^5,21 They can lose their jobs, families, friends, and health until they are homeless, hungry, sick, and psychotic. A deteriorating course such as this has typically defined the schizophrenic process, but this concept has been reassessed.^1-6,13,15

Most, but not all, bipolar type I patients experience psychosis. Mr. C’s bipolar symptoms were not initially obvious because of predominant psychosis and were revealed only with specific, focused questions. Without the student case conference, his diagnosis might have remained schizophrenia. His treatment would have remained substandard because of the conventional belief that schizophrenia requires lifelong antipsychotics, usually without mood stabilizers.

Our patient satisfied all DSM-IV-TR criteria for both schizophrenia and psychotic bipolar. Bleuler and Schneider would have diagnosed him as having schizophrenia because they thought all psychotic disorders were schizophrenic.^10,12 They were incorrect, as psychotic symptoms are common in patients with severe bipolar disorder.^1-6,13,22

Cinical implications

Our observations about this case suggest four important clinical questions:

• Do data justify diagnosing patients such as Mr. C with bipolar disorder and not schizophrenia?
  
• Do data substantiate either diagnosis as valid?
  
• Does the diagnosis matter?
  
• What is standard-of-care treatment for these patients?
  

Which diagnosis? No psychiatric disorder can be validated as rigorously as Koch’s postulates did for infectious diseases. To be considered scientifically grounded, a psychiatric illness must show one or more symptoms not found in any other disorder. Bipolar disorder meets this criterion; schizophrenia does not because the psychotic symptoms and chronic course used to diagnose it are not disease-specific. Psychotic symptoms are not diagnostic of bipolar disorder but define its severity.⁶

Evidence for validity? Bipolar disorder’s two extremes in mood and behavior are so different from those in persons without bipolar disorder or with any other condition that homogeneous bipolar populations can be identified and studied with confidence.^2,5,13,21 DSM-IV-TR diagnostic symptoms for bipolar disorder are unique (Table 2).

For a psychiatric disorder to be considered valid, patients must share other characteristics. Bipolar disorder has been validated as a specific disease by consistent genetic,^1,13,23,24 pharmacologic,^2,14,15 and epidemiologic¹ data accumulated across 30 years. The concordance for bipolar disorder in monozygotic twins is approximately 75%, and susceptibility loci for bipolar disorder are established.^23,24

Table 2

Characteristics indicating a mood disorder, not schizophrenia*

History	Past diagnosis or symptoms of a mood disorder; family history of mood disorder or alcoholism
Past medications	Lithium, valproic acid, or other mood stabilizers
Periods of uncharacteristic and excessive goal-directed activities	Political, religious, legal, sexual, business, criminal, medical, physical, spending, calling, writing, preaching, cleaning, planning, exercise
Presence of uncharacteristic emotions or conflict	Irritability, anger, violence, conflict with law enforcement, elation, grandiosity (paranoia), sadness, hopelessness, crying, suicidal ideation
Periods of appropriate affect	Smiles, laughs, cries, irritable, angry
Mood-congruent delusions and/or hallucinations	Consider grandiosity when there is paranoia and fear
Episodes of relatively normal function/remission; premorbid personality positive	Friends, dating, team sports, group activities, election to an office/title, club or gang memberships
Current social interactions	Enjoys a friendship, active interactions with spouse and own children, regular interactions with others
*Absence of any or all does not rule out mood disorder.