Hypersensitivity to 35% carbon dioxide in patients with adult separation anxiety disorder

A systematic review and network meta-analysis of carbon dioxide provocation in psychiatric disorders

BACKGROUND

False suffocation alarm hypothesis has been widely used to explain carbon dioxide hypersensitivity in panic disorder (PD). However, hypersensitivity to carbon dioxide has been observed in other psychiatric disorders. We explored the specificity of carbon dioxide inhalation as a panic provocation test among psychiatric disorders via network meta-analysis.

METHODS

A systematic literature search on PubMed, EMBASE, and PsycNET was performed to acquire the studies using the carbon dioxide provocation test in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and checklists. Odds ratios (OR) for a panic attack (PA) induced by the carbon dioxide inhalation tests were extracted from each of the original studies and were pooled using the random-effects model.

RESULTS

Network meta-analysis on a pool of 2181 participants from 41 studies was used to compare the efficacy of carbon dioxide provocation tests among psychiatric disorders. The network meta-analysis showed that the odds for PA in response to carbon dioxide inhalation are higher in patients with PD, premenstrual dysphoric syndrome (PMDD), and social anxiety disorder (SAD) than healthy controls (HC). The odds for PA were not significantly different among patients with generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), major depressive disorder (MDD), and healthy controls (HC).

CONCLUSIONS

The vulnerability to the carbon dioxide provocation test is not limited to PD. The specificity of the test for PD is questionable, as individuals suffering from PMDD and SAD are also significantly more responsive to carbon dioxide inhalation compared to HC, OCD, MDD, and GAD. There may be shared underpinning biological mechanisms between PD, PMDD, and SAD.

Comparison of Sodium Lactate Infusion and Carbon Dioxide Inhalation Panic Provocation Tests: A Meta-analysis

BACKGROUND

Sodium lactate (NaL) infusion and carbon dioxide (CO₂) inhalation are proven to provoke acute panic attacks (PAs) in patients with panic disorder (PD). A systematic literature search and meta-analysis were performed to compare the effect sizes of these methods.

METHODS

Odds ratios were calculated for each of the original studies and were pooled using the random-effects model.

RESULTS

Either NaL or CO₂ provocations significantly increased the rates of PAs in individuals with PD compared to those in healthy controls. However, the effect size of NaL infusion (OR=25.13, 95% CI=15.48-40.80) was significantly greater than that of CO₂ inhalation (OR=10.58, 95%CI=7.88-14.21).

CONCLUSION

The evidence for the efficacy of the two panic provocation tests is very strong. Yet, the results support the superiority of NaL infusion over CO₂ inhalation challenge as a panic provocation test. Thus, lactate seems a much stronger stimulus than CO₂ for the brain suffocation detector.

Separation anxiety disorder among outpatients with major depressive disorder: Prevalence and clinical correlates

Prior studies have reported that separation anxiety disorder (SEPAD) can continue into or may begin in adulthood. Association of SEPAD with other psychiatric disorders has been frequently examined, and high rates of comorbidities have been found. The aim of this study was to investigate the prevalence and clinical correlation of SEPAD in adult patients undergoing treatment for major depressive disorder (MDD). The study sample was comprised of 100 outpatients. Participants underwent a DSM-5-based comprehensive assessment. Purposefully-designed semi-structured sociodemographic information and illness history forms were filled out by the researchers, and diagnoses of SEPAD were made using the Structured Clinical Interview for Separation Anxiety Symptoms, Separation Anxiety Symptom Inventory and Adult Separation Anxiety Survey. The frequency of SEPAD was 41% in patients with MDD, three-quarters of whom were adult onset. The use of new-generation antidepressants, adjunctive medications and comorbidity of other anxiety disorders were higher in patients with SEPAD (p < 0.05). SEPAD was highly prevalent, with a majority of cases starting in adulthood among patients with MDD, while SEPAD comorbidity was associated with high levels of anxiety and an increased likelihood of suboptimal response to usual depression treatment. Further studies are required to define the relevance and pathological basis for the comorbidity of SEPAD in people with MDD.

A neurobiological framework of separation anxiety and related phenotypes

In the DSM-5, separation anxiety disorder (SAD) is newly classified in the chapter on anxiety, renewing research efforts into its etiology. In this narrative review, we summarize the current literature on the genetic, endocrine, physiological, neural and neuropsychological underpinnings of SAD per se, SAD in the context of panic disorder, separation anxiety symptoms, and related intermediate phenotypes. SAD aggregates in families and has a heritability of ~43%. Variants in the oxytocin receptor, serotonin transporter, opioid receptor µ1, dopamine D4 receptor and translocator protein genes have all been associated with SAD. Dysregulation of the hypothalamus-pituitary-adrenal axis, dysfunctional cortico-limbic interaction and biased cognitive processing seem to constitute further neurobiological markers of separation anxiety. Hypersensitivity to carbon dioxide appears to be an endophenotype shared by SAD, panic disorder and anxiety sensitivity. The identification of biological risk markers and its multi-level integration hold great promise regarding the prediction of SAD risk, maintenance and course, and in the future may allow for the selection of indicated preventive and innovative, personalized therapeutic interventions.

[Separation anxiety disorder in adults - a new diagnostic category]

Anxiety separation disorder (SAD) became the subject of increased attention of researchers in recent decades. DSM-5 and project of ICD-11 allow us to treat this disorder as an independent nosological unit without attachment to age. The review provides information on the prevalence, clinical manifestations and diagnosis of SAD in adults, summarizes information on the etiopathogenesis, relations to other psychiatric disorders, and highlights the lack of modern therapeutic approaches to SAD. The purpose of this review is to raise the level of knowledge about SAD and its new positioning in classification systems.

The separation of adult separation anxiety disorder

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) categorization of mental disorders places "separation anxiety disorder" within the broad group of anxiety disorders, and its diagnosis no longer rests on establishing an onset during childhood or adolescence. In previous editions of DSM, it was included within the disorders usually first diagnosed in infancy, childhood, or adolescence, with the requirement for an onset of symptoms before the age of 18 years: symptomatic adults could only receive a retrospective diagnosis, based on establishing this early onset. The new position of separation anxiety disorder is based upon the findings of epidemiological studies that revealed the unexpectedly high prevalence of the condition in adults, often in individuals with an onset of symptoms after the teenage years; its prominent place within the DSM-5 group of anxiety disorders should encourage further research into its epidemiology, etiology, and treatment. This review examines the clinical features and boundaries of the condition, and offers guidance on how it can be distinguished from other anxiety disorders and other mental disorders in which "separation anxiety" may be apparent.

Separation anxiety disorder across the lifespan: DSM-5 lifts age restriction on diagnosis

DSM-5 has lifted the age criterion in the definition of separation anxiety disorder thereby overturning the long-standing convention of restricting the diagnosis to childhood. Previously, adults with separation anxiety symptoms were assigned to other conventional categories such as panic disorder, agoraphobia or generalized anxiety disorder. Over the past two decades, an evolving body of research has identified separation anxiety disorder in adulthood, with 20-40% of adult psychiatric outpatients being assigned that diagnosis. In the US, the lifetime prevalence of the disorder in adulthood is 6.6%. The removal of the age restriction on diagnosis has important implications for clinical practice. Whereas parents (particularly mothers) of children with separation anxiety disorder commonly attracted the diagnosis of agoraphobia, the latter are more likely now to be diagnosed with the adult form of separation anxiety disorder, focusing attention on the importance of intervening with both members of the dyad to overcome mutual reinforcement of symptoms. In addition, adults with separation anxiety disorder have been found to manifest high levels of disability and they tend to show a poor response to conventional psychological and pharmacological treatments. There is an urgent need therefore to devise novel psychological and pharmacological interventions for the adult form of the disorder. The reformulation of separation anxiety disorder in DSM-5 therefore requires a paradigm shift in which clinicians are alerted to identifying and treating the condition in all age groups. Research across countries is needed to examine the new formulation of separation anxiety disorder amongst populations of diverse ethnic and cultural backgrounds.

Separation anxiety disorder in adult patients with obsessive-compulsive disorder: prevalence and clinical correlates

OBJECTIVE

Individuals with obsessive-compulsive disorder (OCD) and separation anxiety disorder (SAD) tend to present higher morbidity than do those with OCD alone. However, the relationship between OCD and SAD has yet to be fully explored.

METHOD

This was a cross-sectional study using multiple logistic regression to identify differences between OCD patients with SAD (OCD+SAD, n=260) and without SAD (OCD, n=695), in terms of clinical and socio-demographic variables. Data were extracted from those collected between 2005 and 2009 via the Brazilian Research Consortium on Obsessive-Compulsive Spectrum Disorders project.

RESULTS

SAD was currently present in only 42 (4.4%) of the patients, although 260 (27.2%) had a lifetime diagnosis of the disorder. In comparison with the OCD group patients, patients with SAD+OCD showed higher chance to present sensory phenomena, to undergo psychotherapy, and to have more psychiatric comorbidities, mainly bulimia.

CONCLUSION

In patients with primary OCD, comorbid SAD might be related to greater personal dysfunction and a poorer response to treatment, since sensory phenomena may be a confounding aspect on diagnosis and therapeutics. Patients with OCD+SAD might be more prone to developing specific psychiatric comorbidities, especially bulimia. Our results suggest that SAD symptom assessment should be included in the management and prognostic evaluation of OCD, although the psychobiological role that such symptoms play in OCD merits further investigation.