Schizophrenia comorbid with panic disorder: evidence for distinct cognitive profiles.

Patients with comorbid schizophrenia and panic symptoms share a distinct clinical presentation and biological characteristics, prompting some to propose panic psychosis as a separate subtype of schizophrenia. Less is known about these patients' neuropsychological profiles, knowledge of which may facilitate target-specific treatments and research into the etiopathophysiology for such cases. A total of 255 schizophrenia patients with panic disorder (n=39), non-panic anxiety disorder (n=51), or no anxiety disorder (n=165) were assessed with the Wechsler Adult Intelligence Scale-Revised, the Wisconsin Card Sorting Test, the Trail Making Test, the Controlled Oral Word Association Test, the Animal Naming subtest of the Boston Diagnostic Aphasia Examination, and the Wechsler Memory Scale-Revised. Psychotic symptoms were assessed with the Positive and Negative Syndrome Scale. Patients with panic disorder demonstrated a higher verbal IQ and better problem solving, set switching, delayed recall, attention, and verbal fluency as compared to schizophrenia patients without comorbid anxiety. The schizophrenia-panic group reported a higher level of dysthymia on stable medication. Our findings suggest that patients with schizophrenia and comorbid panic disorder exhibit distinct cognitive functioning when compared to other schizophrenia patients. These data offer further support for a definable panic-psychosis subtype and suggest new etiological pathways for future research.

Carbon dioxide induction of panic anxiety in schizophrenia with auditory hallucinations.

Panic is commonly co-morbid with schizophrenia. Panic may emerge prodromally, contribute to specific psychotic symptoms, and predict medication response. Panic is often missed due to agitation, impaired cognition, psychotic symptom overlap and limited clinician awareness. Carbon dioxide exposure has been used reliably to induce panic in non-psychotic panic subjects, but has not been systematically studied in schizophrenia. Eight inpatients with schizophrenia, recent auditory hallucinations, none preselected for panic, all on antipsychotic medication, received a structured Panic and Schizophrenia Interview (PaSI), assessing DSM-IV panic symptoms concurrent with paroxysmal auditory hallucinations. On that interview, all eight subjects reported panic concurrent with auditory hallucinations. At one sitting, subjects were exposed, in random order, to 35% carbon dioxide and to placebo room air, blinded to condition. All subjects experienced panic to carbon dioxide, one with limited symptoms. Only one subject panicked to placebo. One subject (one of only two without antipanic medication) had paroxysmal voices concurrent with induced panic. With added adjunctive clonazepam, that patient had marked clinical improvement and no response to carbon dioxide re-challenge. This first systematic examination offers preliminary evidence that carbon dioxide safely induces panic symptoms in schizophrenia. Panic may be prevalent and pathophysiologically significant in schizophrenia with auditory hallucinations.