Epilogue

The authors of the chapters in this volume have covered nearly every feature of depression comorbidity with other psychiatric disorders, chronic health conditions, and disturbed close relationships. Treatment implications are addressed both in chapters on individual disorders as well as comprehensively in separate chapters. This volume concludes with the “big picture” provided by Ronald Kessler and his colleagues. Several themes emerge. Depression comorbidity is pervasive. It touches to one degree or another almost every identifiable psychiatric condition, chronic health condition, and disturbed close relationship. There are numerous potential explanations for this pervasive comorbidity that depend in part on the comorbid disorder. Depression comorbidity is associated with greater disease burden, resistance to treatment, increased primary disease morbidity, and mortality relative to cases in which comorbid depression is not present. Although depression comorbidity is common across psychiatric disorders, it is especially common among the anxiety disorders, raising questions as whether these disorders are really distinct. The assessment and treatment of comorbid disorders is complicated and often requires interdisciplinary collaboration. Although great strides have been made in the study of depression comorbidity, there is much left to be learned, so that we will be able to provide the most effective possible care to our patients who suffer from comorbid depression.