A Revised Theory of Sudden Gains in Psychological Treatments

Sudden gains were first defined and quantified by Tang and DeRubeis (1999) and were found to predict treatment outcome in cognitive therapy for depression. Since that seminal paper, over 100 examinations of sudden gains have been published and sudden gains have been found to be ubiquitous in psychological treatments and to consistently predict better treatment outcomes across a multitude of disorders and contexts (see Shalom & Aderka, 2020 for a review). The research on sudden gains has seen considerable growth over the past 20 years. However, the theory behind sudden gains (which addresses processes leading to sudden gains, and processes resulting from sudden gains) has never been revised. Based on the empirical research which has accrued over the last 20 years, we present an empirically-based revision of the theory of sudden gains. The revised theory addresses both predictors of sudden gains and processes that may lead to sudden gains, as well as the consequences of sudden gains and the processes by which sudden gains can affect outcome. We also present a number of hypotheses that can be derived from the theory as well as the status of empirical evidence supporting these hypotheses. Research and clinical implications are discussed.