摘要：[Background] The cognitive model of depression was highly stimulating for a better understanding and development of treatment for depression. However, the concept of “cognition” is rather broad and unspecific, and we suggest to focus on the cognitive subset of expectation. [Method] We conducted a narrative review on the role of expectations, and present an expectation-focused model of explaining why depression tends to persist despite the occurrence of positive events. [Results] Several results from basic neuroscience to effects in clinical interventions indicate that expectations play a special role not only for the understanding of the development of mental disorders and the effects of treatment approaches, but especially for an improved understanding of the persistence of mental disorders. If expectations are a major mechanism of depression, the treatment of depression must maximize the violation of dysfunctional expectations. We also introduce the concept of immunization that describes any cognitive or behavioral strategies to reduce the effect of expectation violation experiences, and hereby contributing to expectation maintenance despite expectation contradicting events. We postulate that the development of immunization strategies could help to better understand the transition from episodic to chronic depression. [Conclusion] While in early periods of depression development, a focus on expectation change might be sufficient in treatment, the treatment of patients with chronic depression requires addressing these cognitive and behavioral immunization strategies more intensively. Further implications for treatment and research are outlined that are derived from this balance between expectation violation and cognitive immunization in depression.
