Generalized anxiety disorder and its comorbidities: disputes at the boundaries

Prevalence and Clinical Correlates of Comorbid Anxiety and Panic Disorders in Patients with Parkinson's Disease

Mood and anxiety disorders are the most common neuropsychiatric syndromes associated with Parkinson's disease (PD). The aim of our study was to estimate the prevalence of lifetime and current anxiety disorders in patients with Parkinson's Disease (PD), to explore possible distinctive neurological and psychiatric features associated with such comorbidity. One hundred patients were consecutively recruited at the Movement Disorders Section of the Neurological Outpatient Clinic of the University of Pisa. According to the MINI-Plus 5.0.0, 41 subjects were diagnosed with lifetime anxiety disorder (22 with panic disorder) and 26 were diagnosed with current anxiety disorders. Patients with anxiety disorders were more frequently characterized by psychiatric symptoms preceding PD, lifetime major depression and antidepressant treatments. They showed more anxious temperamental traits and scored higher at Parkinson Anxiety Scale (PAS) and persistent anxiety subscale. Current anxiety disorders were associated with more severe psychopathology, depressive symptomatology, and avoidant behavior. Among anxiety subtypes, patients with lifetime panic disorder showed higher rates of psychiatric symptoms before PD, lifetime unipolar depression, current psychiatric treatment, and a more severe psychopathology. Given the overall high impact of anxiety on patients' quality of life, clinicians should not underestimate the extent of different anxiety dimensions in PD.

Comorbidity of personality disorders in anxiety disorders: a meta-analysis of 30 years of research

BACKGROUND

A comprehensive meta-analysis to identify the proportions of comorbid personality disorders (PD) across the major subtypes of anxiety disorders (AD) has not previously been published.

METHODS

A literature search identified 125 empirical papers from the period 1980-2010 on patients with panic disorders, social phobia, generalised anxiety, obsessive-compulsive (OCD) and post-traumatic stress disorder (PTSD). Several moderators were coded.

RESULTS

The rate of any comorbid PD was high across all ADs, ranging from .35 for PTSD to .52 for OCD. Cluster C PDs occurred more than twice as often as cluster A or B PDs. Within cluster C the avoidant PD occurred most frequently, followed by the obsessive-compulsive and the dependent PD. PTSD showed the most heterogeneous clinical picture and social phobia was highly comorbid with avoidant PD. A range of moderators were examined, but most were non-significant or of small effects, except an early age of onset, which in social phobia increased the risk of an avoidant PD considerably. Gender or duration of an AD was not related to variation in PD comorbidity.

LIMITATIONS

Blind rating of diagnoses was recorded from the papers as an indication of diagnostic validity. However, as too few studies reported it the validity of the comorbid estimates of PD was less strong.

CONCLUSIONS

The findings provided support to several of the proposed changes in the forthcoming DSM-5. Further comorbidity studies are needed in view of the substantial changes in how PDs will be diagnosed in the DSM-5.

Diagnostic overlap of generalized anxiety disorder and major depressive disorder in a primary care sample

BACKGROUND

Generalized anxiety disorder (GAD) and major depressive disorder (MDD) are highly comorbid. A possible explanation is that they share four symptoms according to the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition-Text Revision (DSM-IV-TR). The present study addressed the symptom overlap of people meeting DSM-IV-TR diagnostic criteria for GAD, MDD, or both to investigate whether comorbidity might be explained by overlapping diagnostic criteria.

METHODS

Participants (N = 1,218) were enrolled in the Coordinated Anxiety Learning and Management study (a randomized effectiveness clinical trial in primary care). Hypotheses were (1) the comorbid GAD/MDD group endorses the overlapping symptoms more than the nonoverlapping symptoms, and (2) the comorbid GAD/MDD group endorses the overlapping symptoms more than GAD only or MDD only groups, whereas differences would not occur for nonoverlapping symptoms.

RESULTS

The overlapping GAD/MDD symptoms were endorsed more by the comorbid group than the MDD group but not the GAD group when covarying for total symptom endorsement. Similarly, the comorbid group endorsed the overlapping symptoms more than the nonoverlapping symptoms and did not endorse the nonoverlapping symptoms more than the GAD or MDD groups when covarying for total symptom endorsement.

CONCLUSIONS

The results suggest that comorbidity of GAD and MDD is strongly influenced by diagnostic overlap. Results are discussed in terms of errors of diagnostic criteria, as well as models of shared psychopathology that account for diagnostic criteria overlap.

Investigating differential symptom profiles in major depressive episode with and without generalized anxiety disorder: true co-morbidity or symptom similarity?

BACKGROUND

Large community-based epidemiological surveys have consistently identified high co-morbidity between major depressive episode (MDE) and generalized anxiety disorder (GAD). Some have suggested that this co-morbidity may be artificial and the product of the current diagnostic system. Because of the added direct and indirect costs associated with co-morbidity, it is important to investigate whether methods of diagnostic classification are artificially increasing the level of observed co-morbidity.

METHOD

The item response theory (IRT) log-likelihood ratio procedure was used to test for differential item functioning (DIF) of MDE symptoms between respondents with and without a diagnosis of GAD in the 2001-2002 National Epidemiological Survey on Alcohol and Related Conditions (NESARC).

RESULTS

The presence of GAD significantly increased the chances of reporting any symptom of MDE, with odds ratios ranging from 2.54 to 5.36. However, there was no indication of significant DIF of MDE symptoms in respondents with and without GAD.

CONCLUSIONS

The lack of any significant DIF indicates that cases with GAD do not present with a distinct MDE symptom profile, one that is consistent with the endorsement of symptoms that are conceptually similar in nature between the two disorders, compared to cases without GAD. This does not support the hypothesis that co-morbidity between MDE and GAD is artificially inflated because of the similar symptom criteria required by the current diagnostic system. Instead, MDE and GAD may be thought of as two distinct diagnostic entities that frequently co-occur because of a shared underlying trait.

Development and validation of the Generalized Anxiety Disorder Inventory (GADI)

The psychometric tools used for the assessment of generalized anxiety disorder (GAD) either do not conform to the current concept of the condition or have important limitations. We aimed to develop and validate a new questionnaire for the assessment of symptom profile and severity of GAD. An original pool of potential scale items was subjected to a series of studies in non-clinical and clinical populations, in order to determine the final composition of the scale. The psychometric properties of the new scale, the Generalized Anxiety Disorder Inventory (GADI), were evaluated using a factor analytic model suitable for ordinal data and the Graded Response Model. The precision of measurement of the GADI was quantified through the item information functions.A total of 197 outpatients and 522 non-clinical subjects participated in four studies and completed the GADI. The final 18-item scale was derived from an original pool of 30 potential items. The GADI showed good reliability, convergent and divergent validity. The scale comprises three factors, relating to cognitive, somatic and sleep symptoms. It accurately distinguished GAD patients from non-patient controls. The cognitive factor also distinguished GAD from other anxiety disorders and depression. The GADI is a useful tool in the assessment of the breadth of symptoms and the severity of generalized anxiety disorder in clinical settings.

Cognitive-behavioral therapy for anxiety in the elderly

Anxiety is a significant problem among the elderly. Due to complexities in the medical management of elderly patients, researchers and clinicians have sought psychosocial alternatives to pharmacotherapy in order to treat anxiety in the elderly. Cognitive-behavioral therapy (CBT) in particular has been investigated as a promising treatment. Research conducted to date has established that CBT produces significant improvement in anxiety symptoms among the elderly. However, there is some concern that CBT does not benefit elderly anxiety patients as much as it does younger patients. Investigators are seeking methods of augmenting or supplementing CBT in order to develop more effective treatments for anxiety in the elderly.

Broadening the definition of generalized anxiety disorder: effects on prevalence and associations with other disorders in the National Comorbidity Survey Replication

Concerns have been raised that the DSM-IV requirements of 6-month duration, excessive worry, and three associated symptoms exclude a substantial number of people with clinically significant anxiety from a diagnosis of generalized anxiety disorder (GAD). We examined the implications of relaxing these three criteria for the estimated prevalence and predictive validity of GAD using nationally representative data from the US National Comorbidity Survey Replication. Relaxing all three criteria more than doubles the estimated prevalence of GAD. Broadly defined GAD significantly predicts the subsequent first onset of a wide range of temporally secondary disorders. The odds of secondary disorders are somewhat smaller for broadly defined than DSM-IV GAD, though few of these differences are statistically significant. Results suggest that subthreshold manifestations of GAD are significantly related to elevated risk of subsequent psychopathology. Further research is needed to determine whether broadening the current diagnostic criteria results in a more valid characterization of GAD.

The Mood Spectrum Self-Report: validation and adaptation into Spanish

This study explores the psychometric properties of the Spanish adaptation of the Mood Spectrum Self-Report (MOODS-SR), an instrument designed to assess a broad range of manifestations of mood psychopathology. A total of 71 Spanish subjects participated: 49 outpatients who met criteria for a mood disorder or generalized anxiety disorder, and 22 normal controls. The instrument proved to have good internal consistency and test-retest reliability. Significant positive correlations were found between the depressive subdomains of the questionnaire and the Beck Depression Inventory, as well as between the manic-hypomanic subdomains and the Clinician-Administered Rating Scale for Mania. Clinical subjects displayed higher mean scores than normal subjects in all domains, and patients with bipolar disorder displayed higher scores than patients with unipolar disorder in the Manic component, particularly in the Energy and the Cognition subdomains. Differences between patients with generalized anxiety and mood disorders were small. The former, however, did not differ from normal controls in several subdomains, whereas patients with mood disorders did.

Generalized Anxiety Disorder and major depressive disorder comorbidity in the National Survey of Mental Health and Well-Being

We report population data on DSM-IV Generalized Anxiety Disorder (GAD) from the Australian National Survey of Mental Health and Well-Being, obtained from a nationwide household survey of adults using a stratified multistage sampling process. A response rate of 78.1% resulted in 10,641 persons being interviewed. Diagnoses were made using the Composite International Diagnostic Interview. The interview was computerised and conducted by trained lay interviewers. We investigated comorbidity between GAD and major depressive disorder (MDD). The results indicate that sociodemographic correlates of GAD, and associated disablement and service use, are influenced by the presence of a comorbid depressive disorder but cannot be fully explained by the presence of that disorder. In addition, GAD was confirmed as significantly disabling, even as a single disorder. We conclude that the results are consistent with the view that GAD has a significant and independent impact on the burden of mental disorders.

Infrequency of "pure" GAD: impact of psychiatric comorbidity on clinical course

The widespread occurrence of psychiatric comorbidity among patients with generalized anxiety disorder (GAD) has been well documented. However, there is a paucity of studies examining the impact comorbid disorders have on the clinical course of GAD. In this study, 179 patients with GAD at intake, 12 patients with a past history of GAD, and 109 patients who subsequently onset a first episode of GAD during the course of follow-up were followed for 8 years in this naturalistic, prospective study of anxiety disorders. Results indicate that comorbid anxiety, mood, and substance use disorders are very common with GAD and increased during follow-up. For example, 39% of participants with GAD also had a comorbid diagnosis of major depressive disorder at intake and increased to 65% at 4 years and 74% at the 8-year follow-up. Inspection of "pure" cases of GAD indicated that out of 20 patients with GAD alone at intake, all but 1 went on to develop some comorbidity. Results also indicate that being in episode of comorbid MDD or panic disorder with agoraphobia decreased the probability that a subject would remit from their GAD. The findings highlight the need for such long-term, prospective research since results show that patients with GAD at intake had increasing risk for developing other mental disorders during subsequent follow-ups. Additionally, results of such high comorbidity and the impact of these comorbid disorders on the clinical course of GAD should have a notable impact on research into the treatment of GAD.

One-year prevalence of subthreshold and threshold DSM-IV generalized anxiety disorder in a nationally representative sample

Several studies of representative populations have reported prevalence rates of DSM-III and DSM-III-R generalized anxiety disorder (GAD); however, no community study has examined the effect of the stricter DSM-IV criteria on prevalence estimates and patterns of comorbidity. Furthermore, past studies based on "lifetime" symptom assessments might have led to upper-bound 1-year and point prevalence estimates. Data is presented from a national representative sample study of 4,181 adults in Germany, 18-65 years old, who were interviewed for DSM-IV disorders with the 12-month version of the Munich-Composite International Diagnostic Interview. The prevalence rate of strictly defined, 12-month threshold DSM-IV GAD was estimated to be 1.5%; however, 3.6% of respondents presented with at least subthreshold syndromes of GAD during the past 12 months. Higher rates of worrying and GAD were found in women (worrying 10%, GAD 2.7%) and in older respondents (worrying 9.3%, TAD 2.2%). Taking into account a wider scope of diagnoses than previous studies, a high degree of comorbidity in GAD cases was confirmed: 59.1% of all 12-month GAD cases fulfilled criteria for major depression, and 55.9% fulfilled criteria for any other anxiety disorder. In conclusion, prevalence and comorbidity rates found for DSM-IV GAD are not substantially different from rates reported for DSM-III-R GAD. The minor differences in our findings compared to previous reports are more likely attributable to differences in study methodology rather than changes in diagnostic criteria for DSM-IV.

A twin study of generalized anxiety disorder symptoms, panic disorder symptoms and post-traumatic stress disorder in men

Generalized anxiety disorder (GAD), panic disorder (PD) and post-traumatic stress disorder (PTSD) often co-occur. We investigated whether and to what degree genetic and environmental contributions overlap among symptoms of GAD, symptoms of PD and PTSD. Subjects were 3327 monozygotic and dizygotic male-male twin pair members of the Vietnam Era Twin Registry who participated in a 1992 telephone administration of the Diagnostic Interview Schedule Version 3 Revised (DIS3R). Genetic model fitting was performed to estimate the magnitude of genetic and environmental contributions to the lifetime co-occurrence of GAD symptoms, PD symptoms and PTSD. The liability for GAD symptoms was due to a 37.9% additive genetic contribution common to PD symptoms and PTSD. Liability for PD symptoms was due to a 20.7% additive genetic contribution common to GAD symptoms and PTSD, and a 20.1% additive genetic influence specific to PD symptoms. Additive genetic influences common to symptoms of GAD and PD accounted for 21.3% of the genetic variance in PTSD. Additive genetic influences specific to PTSD accounted for 13.6% of the genetic variance in PTSD. Remaining variance for all three disorders was due to unique environmental factors both common and specific to each phenotype. These results suggest that these disorders each have etiologically distinct components and also have significant genetic and unique environmental contributions in common.

Comorbidity in generalized anxiety disorder

GAD has rates of comorbidity that equal or exceed those of other anxiety disorders, and it is one of the most common comorbid conditions with other disorders. Depressive disorders, especially MDD, and other anxiety disorders, especially panic disorder, most commonly co-occur. The pattern of comorbidity is consistent in community and clinical populations and in children and elderly people. Comorbidity is associated with greater impairment, more treatment seeking, and worse outcome among persons with GAD compared with pure GAD. Likewise, patients with panic disorder and MDD who have coexisting GAD tend to have more severe symptoms and less favorable outcome. The relationship between GAD and MDD seems especially close, and data from twin studies suggest that these conditions share a genetic diathesis. Patients with GAD and coexisting conditions respond less well to psychological and pharmacologic treatment, but, for those who do respond, treatment for the primary disorder often also produces improvement in comorbid conditions. Thus, research continues to show that GAD is important as a primary and a comorbid disturbance.

Natural animal models of human psychiatric conditions: assessment of mechanism and validity

1. The classic animal models for human psychiatric conditions involves rodents. As prey species, their normal behaviors of avoidance would be considered pathological in humans and dogs. Hence, such models may not be homologous for similar behaviors found in psychiatric pathology in humans. 2. Dogs exhibit pathological behavioral conditions that may be equivalent to certain human psychiatric conditions. These canine conditions appear spontaneously or endogenously in the absence of genetic or neurochemcial manipulation, and as such, may be homologous to the human condition. 3. If canine conditions approach homology with human conditions they should have excellent face, predictive, and construct validity. 4. The canine conditions of separation anxiety, obsessive-compulsive disorder, cognitive dysfunction, dominance aggression, and panic disorder have good to excellent validity at all explored levels for human generalized anxiety disorder, obsessive-compulsive disorder, Alzheimer's disease, impulse control disorders, and panic disorder. 5. Natural canine models can aid our understanding of human psychiatric conditions.