Defense mechanisms represent one of the oldest concepts in psychotherapy, first described by Freud in the early 20th century. That the concept has endured and become part of clinical and even popular culture speaks to its importance and utility. Defense mechanisms are automatic processes that protect the individual from anxiety, guilt, and other painful emotions that arise from internal conflicts and traumatic experiences. Defenses can range from adaptive (allowing the conscious processing of internal and external sources of stress) to neurotic (restricting or only partially processing the problem) to maladaptive (inhibiting conscious awareness of distress by distorting reality). High adaptive defenses (altruism, humour, sublimation) often lead to good social and psychological outcomes. Neurotic defenses (repression, intellectualization, displacement) limit the individual in several social and psychological areas. Maladaptive defenses (splitting, denial, projective identification, acting out) distort reality and can lead to even greater social and psychological problems. Defense mechanisms and their level of adaptiveness have long been thought to not only affect an individual’s psychosocial functioning but also affect psychotherapy processes and outcomes. In this study, Mazzeo and colleagues systematically reviewed 46 studies of the empirical research on defense mechanisms and psychotherapy from 1992 to 2025. Their first question was “Do defence mechanisms change as a result of therapy?” They found 16 studies that addressed this question directly. Overall, the research indicates robust evidence that maladaptive defenses decrease and adaptive defenses increase as a result of psychotherapy. Their second question was “Are defense mechanisms predictors of psychotherapy outcomes?” Thirty-one of the studies addressed this question, and the results generally were positive but not uniformly so. Many studies linked more adaptive defenses at pre-treatment to better outcomes, and maladaptive defenses with poorer outcomes and dropping out of therapy. The mixed results came from several studies suggesting that those with more maladaptive defenses needed longer-term treatment.
Practice Implications
The findings of this systematic review indicate that it is useful for a therapist to consider a patient’s level of adaptiveness of defense mechanisms at the start of therapy. Adaptive defense mechanisms are a patient resource that promotes engagement in therapy and its processes. Patients who initially have adaptive defensive functioning (suppression, humour, repression, intellectualization) have the psychological capacity to benefit from shorter-term treatments. Patients who initially have maladaptive defensive functioning (splitting, denial, projective-identification, acting out) have more limited psychological capacities and may benefit more from longer-term treatment to achieve significant improvement in defensive functioning and in symptom change.
Mazzeo, O., Di Giuseppe, M., Lagetto, G., Tanzilli, A., Gennaro, A., & Gelo, O. C. G. (2026). Defense mechanisms and psychotherapy change: A systematic review. Clinical Psychology: Science and Practice. Advance online publication. https://dx.doi.org/10.1037/cps0000366