We describe a new self-report instrument, the Inventory of Depression and Anxiety Symptoms (IDAS), which was designed to assess specific symptom dimensions related to major depression and related anxiety disorders. We created the IDAS by conducting principal factor analyses in three large samples (college students, psychiatric patients, community adults); we also examined the robustness of its psychometric properties in five additional samples (high school students, college students, young adults, postpartum women, psychiatric patients) that were not involved in the scale development process. The IDAS contains 10 specific symptom scales: Suicidality, Lassitude, Insomnia, Appetite Loss, Appetite Gain, Ill Temper, Well-Being, Panic, Social Anxiety, and Traumatic Intrusions. It also includes two broader scales: General Depression (which contains items overlapping with several other IDAS scales) and Dysphoria (which does not). The scales (a) are internally consistent, (b) capture the target dimensions well, and (c) define a single underlying factor. They show strong short-term stability, and display excellent convergent validity and good discriminant validity in relation to other self-report and interviewbased measures of depression and anxiety.

We describe a new self-report instrument, the Inventory of Depression and Anxiety Symptoms (IDAS), which was designed to assess specific symptom dimensions related to major depression and related anxiety disorders. We created the IDAS by conducting principal factor analyses in three large samples (college students, psychiatric patients, community adults); we also examined the robustness of its psychometric properties in five additional samples (high school students, college students, young adults, postpartum women, psychiatric patients) that were not involved in the scale development process. The IDAS contains 10 specific symptom scales: Suicidality, Lassitude, Insomnia, Appetite Loss, Appetite Gain, Ill Temper, Well-Being, Panic, Social Anxiety, and Traumatic Intrusions. It also includes two broader scales: General Depression (which contains items overlapping with several other IDAS scales) and Dysphoria (which does not). The scales (a) are internally consistent, (b) capture the target dimensions well, and (c) define a single underlying factor. They show strong short-term stability, and display excellent convergent validity and good discriminant validity in relation to other self-report and interview-based measures of depression and anxiety.

We explicated the validity of the Inventory of Depression and Anxiety Symptoms (IDAS; Watson et al., 2007) in two samples (306 college students, and 605 psychiatric patients). The IDAS scales showed strong convergent validity in relation to parallel interview-based scores on the Clinician Rating version of the IDAS (IDAS-CR); the mean convergent correlations were .51 and .62 in the student and patient samples, respectively. With the exception of Well-Being, the scales also consistently demonstrated significant discriminant validity. Furthermore, the scales displayed substantial criterion validity in relation to DSM-IV mood and anxiety disorder diagnoses in the patient sample. We identified particularly clear and strong associations between (for a recent review, see Joiner, Walker, Pettit, Perez, & Cukrowicz, 2005). At the same time, however, the accumulating research also has exposed some limitations of these instruments, thereby establishing the need for alternative measures (Joiner et al., 2005). Watson et al. (2007) created the Inventory of Depression and Anxiety Symptoms (IDAS) to complement these traditional measures and to address their limitations.The IDAS differs from these older instruments in two basic ways. First, these traditional measures originally were created to yield a single overall index of symptom severity. These total scores are valuable in many contexts; nevertheless, this focus on global dysfunction ignores the heterogeneous and multidimensional nature of depressive symptoms, and it hampers the identification of meaningful subtypes (Ingram & Siegle, 2002;Joiner et al., 2005). In contrast, the IDAS was specifically designed to contain multiple scales assessing specific symptoms of depression (e.g., insomnia, suicidality, appetite loss).Second, extensive evidence has established that these depression measures are very strongly associated with symptoms of anxiety (e.g., Clark & Watson, 1991;Mineka, Watson, & Clark, 1998;Watson, 2005). Consequently, the original IDAS item pool contained a broad range of anxiety-related symptoms. The inclusion of these items facilitated the development of depression scales with good discriminant validity, and also eventually led to the creation of complementary anxiety scales (e.g., social anxiety, panic). Development and Preliminary Validation of the IDAS Further Validation of the IDAS 4 Development of the IDASAn initial pool of 180 items was subjected to a series of analyses in a large undergraduate sample (see Watson et al., 2007, Study 1); this yielded a revised pool of 169 items. Next, this revised set of items was administered to large samples of college students, psychiatric patients, and community adults (Watson et al., 2007, Study 2). Data from these three samples were subjected to separate series of principal factor analyses. Ten specific content factors emerged in all three samples and were used to create corresponding scales. Five of these scales represent specific symptoms of major depression: Insomnia, Lassitude (which includes items refle...

Since Janet wrote about dissociation in the early 1900s, the relationship between traumatic stress and dissociation has been discussed and debated in the fields of psychology and psychiatry. In the last 25 years, research has been conducted that allows empirical examination of this relationship and the question of how dissociative symptoms are related to posttraumatic stress disorder (PTSD). After defining the types of dissociative experiences that are considered most relevant to PTSD, we present a comprehensive and systematic review of research addressing the relationship between dissociation and traumatic stress; the rise in dissociation after traumatic stress and its subsequent decline over time; the relationship between dissociation and symptoms of PTSD in nonclinical, clinical, and PTSD samples; the conditional probability of high PTSD symptoms when dissociation level is high; the relationships among dissociation and re-experiencing, avoidance, and hyperarousal symptoms of PTSD; and biological studies of disso ciation in PTSD.

The Dissociative Symptoms Scale (DSS) was developed to assess moderately severe levels of depersonalization, derealization, gaps in awareness or memory, and dissociative reexperiencing that would be relevant to a wide range of clinical populations. Structural analyses of data from four clinical and five nonclinical samples ( N = 1,600) yielded four factors that reflected the domains of interest and showed good fit with the data. Sample scores were consistent with expectations and showed very good internal consistency and temporal stability. Analyses showed consistent evidence of convergent and divergent validity, and posttrauma elevations in scores and in patients with posttraumatic stress disorder provided additional evidence of construct validity. Item response theory analyses indicated that the items assessed moderately severe dissociative experiences. Overall, the results provide support for the reliability and validity of DSS total and subscale scores in the populations studied. Further work is needed to evaluate the performance of the DSS relative to structured interview measures and in samples of patients with other psychological disorders.