While AN is characterized by numerous psychological symptoms, behavioral disturbances are central to the illness’s medical morbidity and functional impairment. Simply put, individuals with AN do not eat sufficient calories to maintain a normal weight. This core feature defines the illness, and there are numerous eating- and activity-related behaviors that serve to support the perpetuation of under-eating. Some of these behavioral phenomena (such as avoidance of feared foods, or stereotyped eating behaviors) overlap with disturbances seen in anxiety disorders, including phobic disorders and obsessive compulsive disorder. In addition, individuals with AN and those with anxiety disorders both display an overvaluation of an irrational belief system with dysfunctional behaviors organized around these beliefs. Notably, there symptoms of anxiety within the syndrome of AN, as well as co-occurrence of AN with anxiety disorders.
Patients with AN commonly describe feeling nervous and unable to relax, and endorse physical symptoms of anxiety (e.g., muscle tension, shortness of breath, fidgeting).(14
) Anxiety symptoms are incorporated into diagnostic assessments across eating disorders (27
) and the potential importance of this feature has been considered.(13
) For some patients, these symptoms improve with weight normalization.(15
) However, these studies report that individuals with AN endorse significantly higher levels of anxiety than healthy controls both while underweight and
after weight restoration. Furthermore, patients’ anxiety scores on the Speilberger State-Trait Anxiety Inventory (STAI(16
)), remain elevated in comparison to healthy controls even after one or more years at normal weight.(17
) One recent case-control study evaluated factors that may be associated with remission from AN, and reported that trait anxiety, as measured by the STAI, differentiated patients who remitted from AN from those who did not.(19
) Thus, while patients with AN report some amelioration of anxiety symptoms with weight restoration, they continue to endorse significantly more non-specific anxiety symptoms relative to controls even after maintaining a normal weight. This persistent anxiety has long been recognized clinically,(20
) but has not generally been the focus of treatment.
In addition to the overlap between anxiety and eating disorder symptomatology, there is a high degree of comorbidity between anxiety disorders (e.g., social phobia, obsessive compulsive disorder (OCD), generalized anxiety disorder) and AN, with estimates ranging from 38%(21
) to 60%.(22
) In a study of lifetime diagnoses,(23
) 55–62% of patients with current or past AN had at least one DSM-IV(20
) anxiety disorder diagnosis, with OCD and social phobia occurring most frequently and substantially higher than would be expected in non-eating disordered populations.(24
) Studies have consistently found that in the majority of participants queried, anxiety disorders precede the onset and diagnosis of AN.(21
) Furthermore, patients who were diagnosed with AN and another anxiety disorder (childhood generalized anxiety disorder) manifested more severe symptoms of AN.
Findings from genetic studies further support a relationship between anxiety disorders and AN. For example, one twin study found a shared genetic influence in the development of eating disorders and certain anxiety disorders (overanxious disorder and separation anxiety), though they did not look separately at AN.(25
) Consistent with this finding, a subsequent family study also reported higher rates of anxiety disorders (OCD, generalized anxiety disorder, separation anxiety disorder, social phobia, and panic disorder) among first-degree relatives of patients with AN.(26
In sum, the existing literature supports a link between anxiety and the perpetuation of AN, with anxiety symptoms and comorbid anxiety disorders occurring commonly among patients with AN, and some data indicating potentially shared biological features. Taken together, these findings suggest that anxiety may represent a useful target for clinical intervention in the treatment of AN.