What are the diagnostic tests for generalized anxiety disorder (GAD)?

Diagnostic Tests for Generalized Anxiety Disorder

The primary diagnostic test for generalized anxiety disorder (GAD) is the 7-item Generalized Anxiety Disorder scale (GAD-7), which has good diagnostic accuracy with a sensitivity of 0.64 and specificity of 0.91 at the recommended cut-off score of 10 or higher. 1

Validated Screening and Diagnostic Tools

Primary Screening Instruments

• GAD-7 Scale:

  • 7-item self-report questionnaire
  • Assesses symptoms over the past 2 weeks
  • Items rated as: 0 "not at all," 1 "several days," 2 "more than half the days," and 3 "nearly every day"
  • Content includes: feeling nervous/anxious/on edge, inability to stop/control worry, worrying too much, trouble relaxing, restlessness, irritability, and feeling afraid
  • Scoring interpretation 2:
    • 0-4: None/mild anxiety
    • 5-9: Moderate anxiety
    • 10-14: Moderate to severe anxiety
    • 15-21: Severe anxiety

• GAD-2 Scale:

  • 2-item abbreviated version of GAD-7
  • Similar diagnostic accuracy to GAD-7 (sensitivity 0.68, specificity 0.86 at cut-off ≥3)
  • More efficient for initial screening 1

Additional Validated Assessment Tools

• Beck Anxiety Inventory (BAI):

  • 21-item self-report scale
  • Focuses on somatic symptoms of anxiety
  • Score ≥10 suggests mild anxiety; ≥19 suggests moderate anxiety
  • Specifically designed to discriminate anxiety from depression 2

• Penn State Worry Questionnaire (PSWQ):

  • 16-item scale (8-item abbreviated version also available)
  • Assesses worry severity, the primary symptom of GAD
  • Evaluates prevalence and controllability of pathological worry 2

• Generalized Anxiety Disorder Questionnaire-IV (GAD-Q-IV):

  • 9-item self-report scale
  • Assesses symptoms based on DSM criteria
  • Domains: uncontrollable worry, functional impairment, physical symptoms, and subjective distress 2

• Hospital Anxiety and Depression Scale (HADS):

  • 14-item self-report measure with separate scales for anxiety and depression
  • Score ≥8 on anxiety scale indicates probable anxiety disorder
  • Excludes physical symptom items to reduce confounding in medical settings 2

Diagnostic Criteria Assessment

A comprehensive diagnostic evaluation should assess the following DSM-5 criteria for GAD:

1. Excessive anxiety and worry occurring more days than not for at least 6 months, about multiple events or activities 3

2. Difficulty controlling worry 3

3. Associated symptoms (at least 3 of the following) 3:

   • Restlessness or feeling keyed up/on edge
   • Being easily fatigued
   • Difficulty concentrating or mind going blank
   • Irritability
   • Muscle tension
   • Sleep disturbance

4. Functional impairment: Anxiety, worry, or physical symptoms causing clinically significant distress or impairment in social, occupational, or other important areas of functioning 3

5. Exclusion of other causes: Symptoms not attributable to physiological effects of substances, medical conditions, or better explained by another mental disorder 3

Clinical Assessment Components

Risk Factor Identification

• Family history of anxiety disorders
• Comorbid psychiatric disorders (especially mood disorders)
• History or current alcohol/substance use
• Presence of chronic medical conditions 2

Symptom Evaluation

• Duration and pattern of worry and anxiety
• Range of worry topics (GAD involves worry about multiple life areas)
• Physical manifestations (fatigue, sleep disturbances, muscle tension)
• Degree of functional impairment
• Coping skills and social support 2

Differential Diagnosis Assessment

• Rule out medical causes of anxiety (thyroid disorders, cardiac conditions)
• Substance-induced anxiety (caffeine, medications, illicit drugs)
• Other anxiety disorders (panic disorder, social anxiety disorder)
• Mood disorders with anxiety features 2, 3

Special Considerations

• Emergency evaluation is required if there is risk of harm to self/others, severe agitation, psychosis, or confusion 2

• Cultural factors should be considered when interpreting symptoms and test results, as anxiety may present differently across cultures 2

• Age-specific considerations are important, as anxiety presentations vary across developmental stages 2

• Comorbidity screening is essential as GAD frequently co-occurs with depression and other anxiety disorders 4, 5

The diagnostic process should be thorough but efficient, as early detection and treatment of GAD significantly improves quality of life and reduces long-term morbidity 6, 4.