The search for determinants of chronic depression: a review of six factors.

While strides have been made in the classification, assessment and identification of chronic depression, there remains a limited understanding of the factors underlying chronicity. This review focuses on six putative determinants of chronic depression: developmental factors, personality and personality disorders, psychosocial stressors, comorbid disorders, biological factors and cognitive factors. The strongest support was found for the role of developmental factors in the chronicity of depression. Some support was found for the role of chronic stressors and certain personality features such as stress reactivity. Few other factors found support. The determinants of chronic depression do not differ qualitatively from acute depression. Rather, the development of chronic depression may involve increased levels of childhood adversity, protracted environmental stress and heightened stress reactivity. However, it is difficult to determine to what extent these putative determinants might reflect retrospective bias in data collection, or even parental reaction to children with subthreshold depressive traits. Detailed etiological models await further research attention to understudied areas and improved research designs. Suggestions for future research include greater specification of criteria for chronicity, use of more appropriate comparison groups and longer term prospective follow-up studies.