Anxiety and Depression Comorbidity: Implications and Intervention

Naomi M. Simon, MD; Jerrold F. Rosenbaum, MD


March 27, 2003

In This Article

Implications of Comorbidity

There has been growing interest and concern about the high rates of comorbidity of anxiety disorders and depression, now clearly documented in both epidemiologic[1] and clinical samples. The presence of comorbidity has been repeatedly shown to have a negative impact on course, including elevated rates of suicidality, greater severity of the primary disorder, greater impairments in social and occupational functioning, and poorer response to treatment.[2,3] For example, a study in a primary care sample found that while the odds of suicidal ideation in patients with major depression alone was 5 times that of patients with no psychiatric disorder, patients with panic disorder comorbid with major depression had triple that (odds ratio = 15.4).[4]

These high rates of lifetime diagnostic comorbidity have also resulted in growing interest in re-examining psychiatric nosology. As the chronicity of mood and anxiety disorders has been recognized, focus has shifted toward lifetime comorbidities and the interaction of risk for one type of mood or anxiety disorder with elevated risk for another. However, some groups have suggested that diagnostic categories in the Diagnostic and Statistical Manual of Mental Disorders are somewhat arbitrarily defined, and that the overlap of anxiety and affective symptoms may be better understood within a spectrum approach, as recently reviewed by Maser and colleagues.[5] The negative impact of panic spectrum symptoms in particular on treatment of both unipolar depression[6] and bipolar disorder[7] has now been well documented. It remains to be shown whether a diagnostic or spectrum approach to comorbidity will be more useful to clinicians in selecting treatment interventions; attempts are ongoing to find differential predictors of response to help guide optimal treatment selection. To date, however, the limited data available about the treatment of anxiety and depression comorbidity have been examined based on diagnostic categories.

There has also been an interest in determining which disorder comes first, anxiety or depression, with the hope of intervening early to prevent the onset of the second disorder. Studies to date, however, have not found a simple answer. While it has been well documented prospectively that an early onset of anxiety disorders predisposes to later onset of major depression,[8] only approximately two thirds of patients with major depressive disorder (MDD) and generalized anxiety disorder (GAD), social anxiety disorder (SAD), or posttraumatic stress disorder (PTSD) have their anxiety disorder onset first, while only one third of patients with panic disorder and MDD do.[9] Further, order of onset has yet to be shown to alter treatment outcome.[10]


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