CATEGORICAL VERSUS DIMENSIONAL DIAGNOSIS OF GENERALIZED ANXIETY DISORDER: HOW WELL DO THEY PREDICT RESPONSE TO TREATMENT?

Open Access
Author:
Ruscio, Ayelet Meron
Graduate Program:
Psychology
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
July 15, 2003
Committee Members:
  • Thomas D Borkovec, Committee Chair
  • Louis Georges Castonguay, Committee Member
  • Michelle Gayle Newman, Committee Member
  • Craig Edelbrock, Committee Member
Keywords:
  • generalized anxiety disorder
  • worry
  • diagnosis
  • classification
  • predictive validity
  • stimulus control interventions
  • self-administered treatments
Abstract:
The present investigation examined three questions related to the diagnosis and treatment of generalized anxiety disorder (GAD). First, is a continuous GAD diagnosis better able to predict the treatment response of worried individuals than a categorical GAD diagnosis? Second, can the known benefits of stimulus control and problem solving interventions for worry be improved by the addition of relaxation training and cognitive restructuring commonly used in the treatment of GAD? Third, does the GAD status of a worried individual interact with the number of therapy components that are received to predict treatment outcome? To address these questions, 72 highly worried individuals were diagnosed under both a categorical (DSM-IV) and a dimensional (severity) GAD model and then provided with one of two brief cognitive-behavioral interventions for severe worry. The two interventions were compared using an additive methodological design and involved a single, group-administered treatment session followed by approximately four weeks of self-guided skills rehearsal and application using a therapy workbook. Participants were assessed for GAD, worry, anxiety, depression, global functioning, and quality of life before and after treatment. Results revealed the dimensional GAD diagnosis to predict some important treatment outcomes more powerfully than the categorical GAD diagnosis, particularly the symptoms and functioning observed at the end of treatment. Results also showed both of the inexpensive, stimulus-control-based anxiety treatments to yield substantial improvement in worrying and associated pathology, with relaxation training and cognitive restructuring providing a small but consistent increment in treatment benefit that appeared especially helpful for non-GAD worriers. Finally, results revealed that while GAD-diagnosed and nondiagnosed high worriers benefited considerably from these worry-focused treatments, GAD worriers generally evidenced greater improvement -- but poorer endstate functioning -- than non-GAD worriers. These preliminary findings contribute to ongoing discourse over the relative utility of categorical versus continuous classification models of psychopathology. In addition, they advance efforts to better understand, more usefully diagnose, and more effectively and efficiently treat the symptoms of generalized anxiety.