Development of Scales that Measure Disorder Specific Intolerance of Uncertainty

Thibodeau, Michel Albert
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Faculty of Graduate Studies and Research, University of Regina

Evidence supports intolerance of uncertainty as an important feature of anxiety-based disorders and the construct may also play a role in major depressive disorder. Measures of intolerance of uncertainty have furthered understanding of the construct; however, existing questionnaires measure intolerance of uncertainty in a generalist fashion, not assessing the actual focus of uncertainty (e.g., what someone with panic disorder is uncertain about). This gap in research precludes conclusions regarding the nature of intolerance of uncertainty in anxiety-based disorders and major depressive disorder. The first objective of the study was to develop scales measuring disorder-specific intolerance of uncertainty (DSIU) for generalized anxiety disorder, social anxiety disorder, obsessivecompulsive disorder, posttraumatic stress disorder, health anxiety, panic disorder, specific phobia, and major depressive disorder. The second objective was to explore the relative contribution of DSIU to symptom severity beyond general (or non-specific) intolerance of uncertainty. The study included 920 university students from the University of Regina (n=360, 78% women, mean age=20.89) and the University of Houston (n=560, 86% women, mean age=22.94). Participants completed a bank of 137 items assessing DSIU and also completed symptom measures. Exploratory factor analyses and item characteristic curves highlighted items that warranted discard (addressing objective 1). Path analysis was conducted to explore the relationships between the constructs of interest (addressing objective 2). Exploratory factor analyses supported eight distinct factors across the DSIU items, reflecting the eight proposed scales. DSIU items generally did not crossload onto other DSIU scales or with items from symptom measures; however, items from the DSIU posttraumatic stress disorder scale overlapped substantially with the posttraumatic stress disorder symptoms measure. Examination of item characteristic curves demonstrated that most items measured the latent traits of interest along their full continuum; however, DSIU items for major depressive disorder and panic disorder did not discriminate between lower and medium levels of the latent traits. The finalized DSIU scales included an average of eight items and number of items ranged from 13 (social anxiety disorder) to six (specific phobia). The finalized scales exhibited excellent internal consistency in both samples (α.=86 to α.=95). Non-specific intolerance of uncertainty and DSIU predicted unique variance in symptoms of all disorders. DSIU and non-specific intolerance of uncertainty predicted symptoms of generalized anxiety disorder (β=31 vs. β=45), obsessive-compulsive disorder (β=40 vs. β=41), health anxiety (β=32 vs. β=45), specific phobia (β=22 vs. β=27), and major depressive disorder (β=32 vs. β=39) to a similar extent. DSIU predicted symptoms of social anxiety disorder (β=72 vs. β=18), panic disorder (β=60 vs. β=11) and posttraumatic stress disorder (β=61 vs. β=28) to a greater extent than non-specific intolerance of uncertainty. Individuals with social anxiety disorder, panic disorder, and posttraumatic stress disorder may be concerned primarily with uncertainty regarding situations specific to their symptoms (e.g., social situations in individuals with social anxiety disorder). Individuals with other disorders may also be relatively intolerant of uncertainty regarding other matters of every day life. Differences between these disorders related to DSIU may have implications for theories of how the disorders develop and how they are treated. Novel research using the DSIU scales is needed to further understanding of how DSIU and non-specific intolerance of uncertainty interact to underlie or exacerbate disorders.

A Thesis Submitted to The Faculty of Graduate Studies and Research Doctor of Philosophy in Clinical Psychology, University of Regina. X, 122 p.