Relationship between panic and schizophrenia

Current and potential pharmacological and psychosocial interventions for anxiety symptoms and disorders in patients with schizophrenia: structured review

OBJECTIVE

Between 30% and 62% of patients with schizophrenia present with co-morbid anxiety disorders that are associated with increased overall burden. Our aim was to summarize current and potential interventions for anxiety in schizophrenia.

DESIGN

Structured review, summarizing pharmacological and psychosocial interventions used to reduce anxiety in schizophrenia and psychosis.

RESULTS

Antipsychotics have been shown to reduce anxiety, increase anxiety, or have no effect. These may be augmented with another antipsychotic, anxiolytic, or antidepressant. Novel agents, such as L-theanine, pregabalin, and cycloserine, show promise in attenuating anxiety in schizophrenia. Psychosocial therapies have been developed to reduce the distress of schizophrenia. Cognitive behavioural therapy (CBT) has shown that benefit and refinements in the therapy have been successful, for example, for managing worry in schizophrenia. CBT usually involves more than 16 sessions, as short courses of CBT do not attenuate the presentation of anxiety in schizophrenia. To address time and cost, the development of manualized CBT to address anxiety in schizophrenia is being developed.

CONCLUSIONS

The presence of coexisting anxiety symptoms and co-morbid anxiety disorders should be ascertained when assessing patients with schizophrenia or other psychoses as a range of pharmacological and psychosocial treatments are available.

ENU-mutagenesis mice with a non-synonymous mutation in Grin1 exhibit abnormal anxiety-like behaviors, impaired fear memory, and decreased acoustic startle response

BACKGROUND

The Grin1 (glutamate receptor, ionotropic, NMDA1) gene expresses a subunit of N-methyl-D-aspartate (NMDA) receptors that is considered to play an important role in excitatory neurotransmission, synaptic plasticity, and brain development. Grin1 is a candidate susceptibility gene for neuropsychiatric disorders, including schizophrenia, bipolar disorder, and attention deficit/hyperactivity disorder (ADHD). In our previous study, we examined an N-ethyl-N-nitrosourea (ENU)-generated mutant mouse strain (Grin1(Rgsc174)/Grin1+) that has a non-synonymous mutation in Grin1. These mutant mice showed hyperactivity, increased novelty-seeking to objects, and abnormal social interactions. Therefore, Grin1(Rgsc174)/Grin1+ mice may serve as a potential animal model of neuropsychiatric disorders. However, other behavioral characteristics related to these disorders, such as working memory function and sensorimotor gating, have not been fully explored in these mutant mice. In this study, to further investigate the behavioral phenotypes of Grin1(Rgsc174)/Grin1+ mice, we subjected them to a comprehensive battery of behavioral tests.

RESULTS

There was no significant difference in nociception between Grin1(Rgsc174)/Grin1+ and wild-type mice. The mutants did not display any abnormalities in the Porsolt forced swim and tail suspension tests. We confirmed the previous observations that the locomotor activity of these mutant mice increased in the open field and home cage activity tests. They displayed abnormal anxiety-like behaviors in the light/dark transition and the elevated plus maze tests. Both contextual and cued fear memory were severely deficient in the fear conditioning test. The mutant mice exhibited slightly impaired working memory in the eight-arm radial maze test. The startle amplitude was markedly decreased in Grin1(Rgsc174)/Grin1+ mice, whereas no significant differences between genotypes were detected in the prepulse inhibition (PPI) test. The mutant mice showed no obvious deficits in social behaviors in three different social interaction tests.

CONCLUSIONS

This study demonstrated that the Grin1(Rgsc174)/Grin1+ mutation causes abnormal anxiety-like behaviors, a deficiency in fear memory, and a decreased startle amplitude in mice. Although Grin1(Rgsc174)/Grin1+ mice only partially recapitulate symptoms of patients with ADHD, schizophrenia, and bipolar disorder, they may serve as a unique animal model of a certain subpopulation of patients with these disorders.

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.

Psychiatric comorbidities and schizophrenia

Psychiatric comorbidities are common among patients with schizophrenia. Substance abuse comorbidity predominates. Anxiety and depressive symptoms are also very common throughout the course of illness, with an estimated prevalence of 15% for panic disorder, 29% for posttraumatic stress disorder, and 23% for obsessive-compulsive disorder. It is estimated that comorbid depression occurs in 50% of patients, and perhaps (conservatively) 47% of patients also have a lifetime diagnosis of comorbid substance abuse. This article chronicles these associations, examining whether these comorbidities are "more than chance" and might represent (distinct) phenotypes of schizophrenia. Among the anxiety disorders, the evidence at present is most abundant for an association with obsessive-compulsive disorder. Additional studies in newly diagnosed antipsychotic-naive patients and their first-degree relatives and searches for genetic and environmental risk factors are needed to replicate preliminary findings and further investigate these associations.

Twins discordant for schizophrenia: psychopathology of the non-schizophrenic co-twins

OBJECTIVE

Patients with schizophrenia are more likely to suffer from mood and anxiety disorders compared with the general population. We explored the aetiology of this comorbidity using a twin study design.

METHOD

We applied an additive genetic + unique environment (AE) random effects model in the analysis of 35 non-schizophrenic co-twins from pairs discordant for schizophrenia, and 131 control twins.

RESULTS

Non-schizophrenic co-twins had significantly increased rates of depression (P = 0.006) and anxiety disorders (P = 0.021) compared with the control twins.

CONCLUSION

Our results provide evidence for a familial association between schizophrenia and anxiety and depression. This could reflect common aetiological factors contributing to each of the disorders. Future studies should attempt to investigate the relative genetic and environmental contribution to the shared risk factors for schizophrenia, mood and anxiety disorders.

[The contribution of brain imaging to the study of panic disorder]

AIMS

The present review is aimed to evaluate the recent contribution of brain imaging techniques to the definition of neuroanatomofunctional models of panic disorder (PD).

METHODS

Structural and functional brain imaging studies of PD, conducted from January 1993 to October 2003 and selected through a comprehensive Medline search (key-words: panic disorder, emotions, brain imaging, EEG, Event-Related Potentials, MRI, fMRI, PET, SPECT, TC) were included in the review. The Medline search has been complemented by bibliographic cross-referencing.

RESULTS

The majority of the reviewed studies suggests that a dysfunction of a neural circuit encompassing prefrontal and temporo-limbic cortices is present in PD. A right hemisphere preferential involvement in PD has been shown by several studies.

CONCLUSIONS

Reviewed neuroimaging studies suggest a dysfunction of frontal and temporo-limbic circuitries in PD. However, those studies cannot be considered conclusive because of several methodological limitations. Longitudinal and multi-modal studies involving larger patient samples, possibly integrated with population-based and genetic studies, would provide more insight into pathophysiological mechanisms of PD.

DECLARATION OF INTEREST

Authors declare that none of them had any known real, potential, or apparent conflict of interest and that there was no business or personal interest that might be relevant to the topic of this article.

Prevalence and relationship to delusions and hallucinations of anxiety disorders in schizophrenia

We investigated the prevalence of anxiety disorders in a sample of individuals with chronic schizophrenia, controlling for anxiety symptoms that may be related to delusions and hallucinations, and the possible differences in clinical variables between the groups. Individuals with a diagnosis of schizophrenia and able to give informed consent were recruited from the community. The Mini International Neuropsychiatric Interview (MINI) was administered to both confirm the DSM-IV diagnosis of schizophrenia and screen for comorbid anxiety disorders. If a comorbid anxiety disorder was found, its relation to the individual's delusions and hallucinations was examined. Clinical rating scales for schizophrenia were administered as well as rating scales for specific anxiety disorders where appropriate. Overall, anxiety disorders ranged from 0% [ for Post Traumatic Stress Disorder (PTSD)] to 26.7% [ for generalized anxiety disorder (GAD) and agoraphobia without panic] with lower rates when controlled for anxiety symptoms related to delusions and hallucinations. In investigating clinical variables, the cohort was initially divided into schizophrenics with no anxiety disorders and those with an anxiety disorder; with further analyses including schizophrenics with anxiety disorders related to delusions and hallucinations and those with anxiety disorders not related to delusions and hallucinations. The most consistent difference between all the groups was on the PANSS-G subscale. No significant differences were found on the remaining clinical variables. Comorbid anxiety disorders in schizophrenia can be related to the individual's delusions and hallucinations, though anxiety disorders can occur exclusive of these positive symptoms. Clinicians must be aware that this comorbidity exists in order to optimize an individual's treatment.

Anxiety and substance use comorbidity among inpatients with schizophrenia

OBJECTIVE

To determine the association between lifetime anxiety symptoms and anxiety disorders and substance use disorders among patients with schizophrenia.

METHOD

Participants were 184 inpatients with schizophrenia at the Schizophrenia Research Unit (SRU) at the New York State Psychiatric Institute (NYSPI). Multivariate logistic regression analyses were used to determine the relationship between specific anxiety symptoms and anxiety disorders and substance use disorders among inpatients with schizophrenia.

RESULTS

Anxiety symptoms and anxiety disorders were prevalent among 31.5% of the sample. Panic attacks were associated with a significantly increased odds (OR=7.4 (1.2, 47.1)) of comorbid alcohol or substance use disorders (lifetime). This association was specific to panic attacks and persisted after adjusting for differences in sociodemographic characteristics and comorbid anxiety symptoms and anxiety disorders.

CONCLUSIONS

These findings are consistent with and extend previous data by providing evidence of an association between panic attacks and increased likelihood of substance use disorders among inpatients with schizophrenia. Future studies that determine the nature of this relationship, the sequence of symptom onsets, and examine whether treatment of anxiety can influence the onset or outcome associated with substance use are needed.

Possible mechanisms of panic attack and schizophrenia via APUD system

Psilocybin poisoning produces biphasic reactions composed of a schizophrenic phase and a panic attack-like phase. There is a time lag of several hours between phases, which may be considered an accumulation time in certain sites between the gut and the brain. So far as 5-hydroxytryptamine (5-HT) congeners are concerned, no sites are to be found except the amine precursor uptake and decarboxylation (APUD) system. It is postulated that argyrophil cells (AC) in the foregut, neuroepithelial bodies (NEB) in the lung, and raphe nuclei (RN) in the brainstem axis are relevant to mental disorders. Schizophrenia might be due to the massive destruction of APUD cells, and the paroxysmal release of 5-HT with peptides and panneuroendocrine markers from NEB might be the cause of panic attack.