Generalization of exposure therapy: Systematic review and recommendations for future research

Limited generalization of exposure therapy effects from treatment-related to treatment-unrelated contexts and/or stimuli is a potential factor contributing to relapse after successful exposure treatment. Investigating the processes underlying exposure therapy generalization (ETG) and developing strategies to promote ETG has become a significant research area. This systematic review provides an overview of the current state of ETG research, outlining its operationalization and the methodological diversity used to detect changes in ETG. We also summarize and discuss findings from studies aimed at enhancing ETG through pharmacological and behavioral interventions. A total of 34 studies were identified, investigating ETG across therapy-related and unrelated contexts and fear stimuli. These studies primarily used physical and/or social context/stimuli manipulations to investigate ETG. Multiple response systems (subjective, psychophysiological, behavioral) were used as indices of diminished ETG, but most studies found increased subjective fear in treatment-unrelated contexts/stimuli compared to treatment-related ones. We conclude that clear definitions and criteria for assessing ETG are urgently needed. Behavioral interventions, such as multiple context exposure or sleep after exposure, seem effective in promoting ETG across different contexts/stimuli. In contrast, findings from pharmacological approaches are less encouraging, but more research is needed. We identify research gaps that require further investigation to better understand the mechanisms governing and promoting ETG. Experimental paradigms offer a clear advantage for this purpose and for screening novel strategies to maximize ETG.