Anxiety Disorders and Depression Comorbidity

The chapter reviews cross-sectional and longitudinal epidemiological studies related to the co-occurrence of anxiety disorders and depression. Results suggest that anxiety disorders and depression tend to co-occur in 20% to 40% of patients. Explanations for increased co-occurrence considered include overlapping diagnostic criteria, genetics, neurophysiology, neurochemistry, negative affect/ temperament, perceived control, interpersonal mechanisms, and biases in information processing. According to most levels of analysis, there is more overlap with GAD and depression while specific phobias have the least overlap. Finally, data on the impact of depression on pharmacological and psychological treatments for anxiety disorders are reviewed. More work is needed to clarify the multiple interactive processes likely at play in the co-occurrence of anxiety and mood disorders and their treatment.