همزمانی اسکیزوفرنی با اختلال پانیک: مدارک و شواهد برای پروفیل های شناختی متمایز

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.

The heterogeneity of schizophrenia precludes efficiency in preventing and treating its effects (Tsuang et al., 1990). Reducing this heterogeneity has thus become an important goal, prompting researchers to look more closely at the experiences of patients with schizophrenia spectrum disorders and other comorbid diagnoses for differences in etiology and presentation (Tsuang et al., 1990). The occurrence of panic symptoms in psychosis is considered subordinate to a primary psychosis diagnosis in hierarchical diagnosis algorithms, but panic-related psychosis has received some attention for having a distinct etiopathophysiology. Unfortunately, despite the potential importance for treatment, cognitive symptoms and profiles in this subgroup have received limited attention from researchers. Schizophrenia has long been known to be highly comorbid with myriad other disorders, including substance abuse (Kamali et al., 2000 and Buckley et al., 2009) and major depression (Fenton, 2001 and Buckley et al., 2009), as well as aggressive behavior (Volavka et al., 1997 and Rasanen et al., 1998). Co-occurring anxiety disorders, particularly obsessive–compulsive disorder, post-traumatic stress disorder, and panic disorder, are now known to be exceptionally prevalent (Achim et al., 2009); although hierarchical diagnosis rules in previous versions of the Diagnostic and Statistical Manual of Mental Disorders may have obscured their presence until recently ( Bermanzohn et al., 2000). Research into these comorbid anxiety disorders has illuminated not only high prevalence rates ( Achim et al., 2009) but separate clinical features as well. Indeed, many patients diagnosed with schizophrenia and obsessive–compulsive disorder appear to have a distinct set of clinical symptoms, neuropsychological features, and treatment responses, prompting researchers to suggest the existence of a “schizo-obsessive disorder” ( Reznik et al., 2001). Researchers make a similar case with regard to schizophrenia and panic symptoms, with some arguing for the existence of a panic psychosis ( Kahn and Meyers, 2000 and Kahn, 2012). Rates of panic symptoms in schizophrenia vary widely due to the population surveyed and varying assessment techniques. Panic attacks have been found to occur in 7.1% ( Goodwin et al., 2003) to 47.5% ( Baylé et al., 2001) of schizophrenia patients, while 4.2% ( Craig et al., 2002) to 35% ( Baylé et al., 2001) meet criteria for panic disorder. A recent meta-analysis found a mean prevalence rate of 9.8% (95% CI, 4.3% to 15.4%) for co-occurring panic disorder in a schizophrenia population ( Achim et al., 2009), compared to a worldwide lifetime prevalence rate of 1.2% (95% CI, 0.7% to 1.9%; Somers et al., 2006). Schizophrenia patients with panic symptoms exhibit some differences in clinical presentation that set them apart from other schizophrenia patients. Data from multiple studies suggest that panic attacks are more common in patients with paranoid schizophrenia, compared to other schizophrenia subtypes (Labbate et al., 1999, Baylé et al., 2001 and Buckley et al., 2009), and it has been proposed that panic may be directly related to delusional fears (Bermanzohn et al., 1999 and Baylé et al., 2001) and to auditory hallucinations (Kahn and Meyers, 2000 and Savitz et al., 2011) in some patients. Patients with schizophrenia and panic attacks or panic disorder also exhibit higher rates of depression (Goodwin and Davidson, 2002 and Ulas et al., 2007), suicidal ideation (Goodwin and Davidson, 2002 and Goodwin et al., 2002), and lifetime substance use (Goodwin et al., 2003). Data on positive and negative symptoms are mixed, with some studies showing no differences from other schizophrenia patients (Higuchi et al., 1999 and Ulas et al., 2010), while other studies report elevations for positive symptoms (Lysaker and Salyers, 2007 and Ulas et al., 2007). Many patients with schizophrenia report having experienced panic prior to the onset of psychosis, which points to the possible role panic may play in the schizophrenia prodrome for panic psychosis (Tien and Eaton, 1992 and Kahn and Meyers, 2000). These patients seem to possess better insight into their illness (Cosoff and Hafner, 1998 and Lysaker and Salyers, 2007), and they are seven times more likely to seek mental health treatment than are schizophrenia patients without panic (Goodwin et al., 2002). Biological evidence for a panic psychosis also exists, though it is limited (Buckley et al., 2009). Heun and Maier (1995) found an increased risk for panic among first-degree relatives of patients with schizophrenia, suggesting a heritable component for the combination. Lyons et al. (2000) provided further support for this notion by showing that the nonaffected, monozygotic twin of an individual with schizophrenia has a 7.5-fold increased odds of a panic disorder diagnosis, though this finding was not statistically significant. Data from pharmaceutical treatment trials are also indicative of the biological etiology of schizophrenia and panic. For example, traditional antipsychotics may worsen panic symptoms in patients with schizophrenia and comorbid panic disorder (Kahn and Meyers, 2000), whereas adjunctive alprazolam or clonazepam may reduce both panic symptoms and psychosis symptoms (Kahn et al., 1988). More recently, researchers have noted the positive effects of atypical antipsychotics as well (Takahashi et al., 2001 and Takahashi et al., 2004). Despite this mounting evidence, the case for a panic-psychosis subtype is still nominal. Buckley et al. (2009) noted a particular lack of investigation into the neurobiological factors of these comorbid disorders. Our study was designed to help address this gap in the literature by examining and comparing cognitive and neuropsychological functioning and symptomatology in schizophrenia patients with panic disorder, non-panic anxiety disorder, or no comorbid anxiety disorder.