Schizophrenia: Other Conditions that Resemble Schizophrenia

Other Conditions that Resemble Schizophrenia

Schizoaffective Disorder

Possibly the most difficult diagnostic dilemma in cases in which a patient has both psychotic symptoms and affective symptoms is in the differentiation between schizophrenia and schizoaffec-tive disorder. There has been some controversy regarding this diagnostic entity. It has been included in studies of both affective disorder and schizophrenia and has at times been considered part of a continuum between the two, which has contributed to some of the diagnostic confusion.

In DSM-IV, schizoaffective disorder is treated as a unique clinical syndrome. A patient with schizoaffective disorder must have an uninterrupted period of illness during which, at some time, they have symptoms that meet the diagnostic criteria for a major depressive episode, manic episode, or a mixed episode concurrently with the diagnostic criteria for the active phase of schizophrenia (criteria A for schizophrenia). Additionally, the patient must have had delusions or hallucinations for at least 2 weeks in the absence of prominent mood disorder symptoms during the same period of illness. The mood disorder symptoms must be present for a substantial part of the active and residual psychotic period. The essential features of schizoaffective dis-order must occur within a single uninterrupted period of illness where the “period of illness” refers to the period of active or re-sidual symptoms of psychotic illness and this can last for years and decades. The total duration of psychotic symptoms must be at least 1 month to meet criteria A for schizophrenia and thus the minimum duration of a schizoaffective episode is also 1 month.

The criteria for a major depressive episode requires a minimum duration of 2 weeks of either depressed mood or mark-edly diminished interest or pleasure. As the symptoms of loss of pleasure or interest commonly occur in nonaffective psychotic disorders, to meet the criteria for schizoaffective disorder cri-teria A, the major depressive episode must include pervasive depressed mood. Presence of markedly diminished interest or pleasure is not sufficient to make a diagnosis as it is possible that these symptoms may also occur with other conditions.

Brief Psychotic Disorder and Schizophreniform Disorder

The distinctions among brief psychotic disorder, schizophreni-form disorder and schizophrenia are based on duration of active symptoms. DSM-IV has established the requirement of 6 months of active, prodromal, and/or residual symptoms for a diagnosisof schizophrenia. Brief psychotic disorder is a transient psychotic state, not caused by medical conditions or substance use, that lasts for at least 1 day and up to 1 month. Schizophreniform disorder falls in between and requires symptoms for at least 1 month and not exceeding 6 months, with no requirement for loss of functioning

Delusional Disorder

If the delusions that a patient describes are not bizarre (e.g., examples of bizarre delusions include the belief that an outside force or person has taken over one’s body or that radio signals are being sent through the caps in one’s teeth), it is wise to consider delusional disorder in the differential diagnosis. Delusional disorder is usually character-ized by specific types of false fixed beliefs such as erotomanic, gran-diose, jealous, persecutory, or somatic types. Delusional disorder, unlike schizophrenia, is not associated with a marked social impair-ment or odd behavior. Moreover, patients with delusional disorder do not experience hallucinations or typically have negative symptoms

Affective Disorder with Psychotic Features

If the patient experiences psychotic symptoms solely during times when affective symptoms are present, the diagnosis is more likely to be mood disorder with psychotic features. If the mood disturbance involves both manic and depressive episodes, the di-agnosis is bipolar disorder. According to DSM-IV, affective dis-orders that are seen in patients with schizophrenia may fall in the category depressive disorder not otherwise specified or bipolar disorder not otherwise specified.

Substance-related Conditions

Psychotic disorders, delirium and dementia that are caused by sub-stance use, in DSM-IV, are distinguished from schizophrenia by virtue of the fact that there is clear-cut evidence of substance use leading to symptoms. Examples of psychotomimetic properties of substances include a PCP psychosis that can resemble schizo-phrenia clinically, chronic alcohol intoxication (Korsakoff’s psy-chosis) and chronic amphetamine administration, which can lead to paranoid states. Therefore, patients who have symptoms that meet criterion A of schizophrenia in the presence of substance use must be reevaluated after a significant period away from the suspected substance, and proper toxicology screens must be per-formed to rule out recent substance abuse.

General Medical Conditions

General medical conditions ranging from vitamin B₁₂ deficiency to Cushing’s syndrome have been associated with a clinical presentation resembling that of schizophrenia. Because the prog-nosis for the associated medical condition is better than that for schizophrenia and the stigma attached to schizophrenia is signifi-cant, it is imperative to provide patients with a thorough medi-cal work-up before giving a diagnosis of schizophrenia. This includes a physical examination; laboratory analyses including thyroid function tests, syphilis screening, and folate and vitamin B₁₂ levels; a CT or MRI scan; and a lumbar puncture when indi-cated in new-onset cases.