Anxiety and Pain
Relative to depression, anxiety disorders have received less attention in the chronic pain literature. Interestingly, the aggregated association of anxiety disorders with chronic pain may be stronger than the association with depression. In the updated Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the American Psychiatric Association (APA) moved post-traumatic stress disorder (PTSD) out of the chapter on anxiety disorders and put it into a new chapter.1 This reflects the recognition that PTSD is its own disorder, while still maintaining a close relationship with anxiety disorders, obsessive-compulsive and related disorders (OCD), and dissociative disorders.1 Most prior pain research has evaluated the effects of anxiety disorders overall, including PTSD, on chronic pain and vice versa.2-4 Therefore, in this review, we present the research as such but include specific sections dedicated to the trauma and stress-related disorders.
Diagnosis of Anxiety Disorder
Anxiety disorders cause distress in more than 30 million Americans in their lifetimes.5 The direct and indirect costs of anxiety disorders are estimated to be about $42 billion per year in the United States.6 Anxiety disorders impair work, and social and physical functioning.7 There also appears to be an elevated prevalence of anxiety disorders among individuals with a variety of medical conditions, including arthritis.8
The 12-month prevalence of anxiety disorders among all US adults is listed in Table 1.9-12 Earlier pain research listed the overall prevalence of comorbid anxiety disorders and pain as ranging between 16.5% and 28.8%.13 Newer studies suggest that anxiety disorders may be present in up to 60% of patients with chronic pain.3 Of course, these estimates are dependent on the methods used to assess for anxiety, the DSM criteria employed, and the spectrum of anxiety disorders included in the studies. In the US National Comorbidity Survey Part II, anxiety disorders were present in 35% of adults in the community with chronic arthritic pain versus 17% of the general population.14 In the Midlife Development in the US Survey (MIDUS), these findings were replicated and extended to persons with migraines and chronic back pain.15
Little consistency exists in the chronic pain literature about specific anxiety disorder diagnoses, but it appears that panic disorder16-18 and generalized anxiety disorder (GAD)18-20 are diagnosed most commonly. Panic disorder and pain share several psychological vulnerabilities, such as hyperarousal, somatic cues, and attentional biases, which may underlie both the anxiety and pain conditions.15 It also is possible that individuals use worry as a strategy for reducing somatic arousal associated with pain, making them more prone to developing GAD.15 In addition, studies have suggested that people with chronic pain may have a pre-existing anxiety disorder21,22 and/or report the onset of anxiety after experiencing pain.22 There is a growing understanding of the impact of anxiety and fear upon chronic pain and vice versa, and their overlap is common.23 More severe chronic pain has been associated with more severe anxiety symptoms.24 The presence of anxiety also has been shown to lead to more frequent reports of pain.25
How Is the Diagnosis of Anxiety Disorder Different in the New DSM-5?
DSM-5 has several changes related to anxiety disorders. In addition to the creation of new sections for PTSD and OCD, the diagnoses of agoraphobia, specific phobia, and social anxiety have been updated.1 In addition, panic attacks now can be categorized as either expected or unexpected, rather than by type as outlined in the DSM-IV-TR. Furthermore, panic disorder and agoraphobia are no longer linked together, and are now recognized as 2 separate disorders. Childhood and adolescent anxiety disorders, such as separation anxiety and selective mutism, have been moved to the chapter on anxiety disorders.26
Assessments for Anxiety Disorders
The use of structured diagnostic interviews by trained mental health professionals is recommended to assess anxiety disorders among adults.22 Perhaps the most commonly recognized self-report measure used to assess for anxiety is the Beck Anxiety Inventory27 and the anxiety scales of the Brief Symptom Inventory.28 Some measures, such as the State-Trait Anxiety Inventory, are characterized more accurately as measures of general distress.29 Other instruments measure a specific diagnosis, such as the Mobility Inventory for agoraphobia,30 and some measure major symptoms particular to a diagnosis, such as the Penn State Worry Questionnaire, which measures worry in GAD.31
Treatment of Anxiety Disorders
A variety of cognitive and behavioral treatment approaches have been studied for chronic pain and anxiety, including breathing control, muscle relaxation, exposure therapy, attention-diversion, desensitization, and hypnosis.23,32 According to the American Psychological Association’s (Division 12) Society of Clinical Psychology, the treatment of anxiety consists primarily of cognitive and behavioral therapies (CBTs), regardless of the particular type of anxiety disorder.33