Anxiety disorders are common in depressed patients. Several studies of the full range of Diagnostic and Statistical Manual of Mental Disorders-defined anxiety disorders in depressed psychiatric outpatients each found that when diagnoses are based on semi-structured diagnostic interviews >40% of the patients had a comorbid anxiety disorder. The recognition of comorbidity is not simply of academic interest, but it has important clinical significance. Epidemiological studies, such as the National Comorbidity Study, have demonstrated that depressed individuals with a history of anxiety disorders are at increased risk for hospitalization, suicide attempt, and greater impairment from the depression. The co-occurrence of anxiety disorders in depressed patients has been associated with a more chronic course of depression in psychiatric patients, primary care patients, and epidemiological samples. Recent research has suggested that clinicians underrecognize anxiety disorder comorbidity in depressed patients. The clinical significance of this underrecognition is highlighted by the finding that patients often want treatment to address their anxiety disorder comorbidity. When anxiety disorders are detected they often influence clinicians' selection of antidepressant medication, though some of clinicians' prescribing biases are not supported by empirical data.

In this monograph, Iwona Chelminski, PhD, reviews the significance of anxiety in patients with depression as well as diagnostic instruments for recognizing this comorbidity. Next, Mark Zimmerman, MD, addresses the factors that affect the clinician's choice of antidepressant, focusing on the influence of comorbid anxiety. Finally, Sidney Zisook, MD, discusses the differential efficacy of antidepressants as well as the role of psychotherapy in patients with comorbid anxiety and depression.