Integrating structural and epidemiological research to inform the classification of psychopathology

Normal Versus Pathological Mood: Implications for Diagnosis

Is there a clear line between normal and abnormal mood? Studies of manifest and latent structure provide strong support for a continuum that extends from asymptomatic to subsyndromal to syndromal cases of increasing severity. Subsyndromal symptoms are impairing, predict syndrome onset and relapse, and account for more doctor's visits and suicide attempts than the full syndromes, yet they are not recognized in the current classification. For most research and some clinical activities, dimensional diagnoses are recommended, and examples are offered for how such diagnoses could be made. For clinical activities requiring decisions, a multithreshold model is proposed in which both lower (e.g., mild depression, capturing subsyndromal cases) and upper (e.g., major depression, capturing clinically significant cases) diagnostic categories are used to inform clinical care. Beyond its implications for diagnosis, the dimensionality of depression and anxiety has implications for etiology and for research aimed at understanding how emotions become disrupted in psychopathology.

Mild to severe social fears: ranking types of feared social situations using item response theory

Social anxiety disorder is one of the most common mental disorders, and is associated with long term impairment, distress and vulnerability to secondary disorders. Certain types of social fears are more common than others, with public speaking fears typically the most prevalent in epidemiological surveys. The distinction between performance- and interaction-based fears has been the focus of long-standing debate in the literature, with evidence performance-based fears may reflect more mild presentations of social anxiety. This study aims to explicitly test whether different types of social fears differ in underlying social anxiety severity using item response theory techniques. Different types of social fears were assessed using items from three different structured diagnostic interviews in four different epidemiological surveys in the United States (n=2261, n=5411) and Australia (n=1845, n=1497); and ranked using 2-parameter logistic item response theory models. Overall, patterns of underlying severity indicated by different fears were consistent across the four samples with items functioning across a range of social anxiety. Public performance fears and speaking at meetings/classes indicated the lowest levels of social anxiety, with increasing severity indicated by situations such as being assertive or attending parties. Fears of using public bathrooms or eating, drinking or writing in public reflected the highest levels of social anxiety. Understanding differences in the underlying severity of different types of social fears has important implications for the underlying structure of social anxiety, and may also enhance the delivery of social anxiety treatment at a population level.

Taxometric analysis of DSM-IV and DSM-5 alcohol use disorders

BACKGROUND

With preparations currently being made for the Diagnostic and Statistical Manual of Mental Disorders-5th Edition (DSM-5), one prominent issue to resolve is whether alcohol use disorders are better represented as discrete categorical entities or as a dimensional construct. The purpose of this study was to investigate the latent structure of DSM-4th edition (DSM-IV) and proposed DSM-5 alcohol use disorders.

METHODS

The study used the Wave 2 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to conduct taxometric analyses of DSM-IV and DSM-5 alcohol use disorders defined by different thresholds to determine the taxonic or dimensional structure underlying the disorders.

RESULTS

DSM-IV and DSM-5 alcohol abuse and dependence criteria with 3+ thresholds demonstrated a dimensional structure. Corresponding thresholds with 4+ criteria were clearly taxonic, as were thresholds defined by cut-offs of 5+ and 6+ criteria.

CONCLUSIONS

DSM-IV and DSM-5 alcohol use disorders demonstrated a hybrid taxonic-dimensional structure. That is, DSM-IV and DSM-5 alcohol use disorders may be taxonically distinct compared to no disorder if defined by a threshold of 4 or more criteria. However, there may be dimensional variation remaining among non-problematic to subclinical cases. A careful and systematic program of structural research using taxometric and psychometric procedures is warranted.

The diagnostic threshold of generalized anxiety disorder in the community: a developmental perspective

Discussion surrounds the question as to whether criteria for generalized anxiety disorder (GAD) should change, particularly in youth. This study examines the effects of possible criteria changes on GAD prevalence and clinical correlates. DSM-IV GAD was assessed using the M-CIDI in a community sample of adolescents and young adults. Diagnostic thresholds were modified in two age spans (9-20 and 21-34 years) using a person-by-year data file (N = 38,534 cases). Relaxing the duration or excessiveness criteria led to the most pronounced changes in GAD prevalence, while relaxing frequency, uncontrollability, or associated-symptom criteria had smaller effects. A lower duration requirement increased rates more in older than younger age spans. Opposite effects occurred for changes in associated-symptoms or clinical-significance criteria. Broader GAD definitions identified cases in both age spans that appeared mostly milder than DSM-IV cases but that still differed from non-GAD cases in various clinical factors and validators. Developmental aspects require stronger consideration in future diagnostic systems.

The latent structure of social anxiety disorder: consequences of shifting to a dimensional diagnosis

Despite longstanding debate over the nature of the boundary between social anxiety disorder (SAD) and less severe social anxiety, no study has tested directly whether the defining features of the disorder correspond to a latent category or dimension. The present study examined this question using data from the National Comorbidity Survey Replication (NCS-R), a nationally representative survey of the U.S. household population. Indicators representing the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) criteria for SAD were submitted to taxometric analyses in a subsample of adults (n = 2,166) who reported excessive social fear in their lifetime. Multiple taxometric procedures and consistency tests converged on a dimensional solution, suggesting that SAD is continuous with milder social anxiety. In follow-up analyses, a dimensional SAD diagnosis outperformed the DSM-IV diagnosis in predicting the subsequent onset of a range of clinically important outcomes. Large differences in associations with comorbid mood disorders, suicidality, and treatment seeking in particular favored the prognostic value of dimensional over categorical diagnosis. These findings support the validity and potential utility of a dimensional conceptualization of SAD that may inform efforts to revise the diagnosis for DSM-V.