The epidemiology of comorbidity between depression, anxiety disorders and somatic diseases.

Depression, generalized anxiety disorder and somatoform disorder are the most common psychiatric disorders in primary care and in the general population. These disorders also show an excess comorbidity which is substantially more common than expected on the basis of their prevalence rates both in primary care as well as in general population. There is no unique mechanism accounting for each of these excess comorbidity constellations. Multiple consequences underline the clinical relevance of comorbidity between these disorders: more psychosocial disability, substantially elevated risk for completed suicides and suicide attempts, worse clinical outcome and treatment response. Recognition of comorbidity is essential for improvement of treatment.