Life Stress and Major Depression: The Mysteries of Recurrences

Approximately half of the people who suffer a major depressive episode for the first time experience recurrences, while the other half do not. Among the initially depressed, however, who will have recurrences remains a mystery, and cannot be forecasted with any statistical or clinical confidence. It is well documented, though, that highly stressful life events commonly precede first episodes of major depression, and that these experiences become progressively less common prior to recurrences. Determining the basis for this consistent empirical observation holds promise for discovering among the initially depressed who will become recurrent, helping to solve the current-day conundrum of recurrences. The present article has 2 overarching objectives. First, we evaluate stress sensitization, the prevailing theory for explaining the decreasing association of major life events with successive recurrences. Conceptual gaps, discrepancies, and misunderstandings are found for understanding the decreasing association, as well as for understanding recurrences. Research practices and logical errors also are exposed that compromise the integrity of the existing empirical record. Second, alternative theoretical accounts are proposed to explain the decreasing association of major life stress with recurrences. Two "dual pathway models" provide viable alternative explanations, fill in existing theoretical gaps, and supply additional advantages for understanding life stress, depression, and recurrences. Recommendations are made for evaluating the 3 respective models. In closing, limitations and remaining questions are discussed for discovering who, early in the lifetime course of major depression, is likely to have a lifetime of repeated recurrences.