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Sudden Gains Can Occur in Psychotherapy Even When the Pattern of Change Is Gradual


Address correspondence to Cannon Thomas, San Francisco Group for Evidence-Based Psychotherapy, 1777 Union Street, San Francisco, CA 94123. E-mail:


Certain large decreases in symptoms between consecutive sessions of psychotherapy, called sudden gains, have been characterized as unique, pivotal events in the course of change. We asked whether a sudden gain is necessarily a qualitatively distinct change, or whether it might be the largest and most stable gain occurring in a gradual course of change. We conducted simulations that showed that sudden gains with most of the characteristics reported in prior research occurred even when change followed a gradual course, and we performed regression analyses that showed that sudden gains did not add any unique predictive power to the ability of the slope of early gradual change to predict post-treatment outcome.