The dose-effect relationship in psychodynamic psychotherapy with people with intellectual disabilities

Background Although there is an established body of evidence attesting to the dose-effect relationship in psychotherapy with non-disabled adults, the issue as to whether such a relationship exists for persons with intellectual disabilities has not been previously examined. Dose-effect essentially concerns the amount of psychotherapy required to produce positive results. Methods The current study used a naturalistic design to examine and compare the outcomes of three groups of participants with co-morbid psychological problems undergoing treatments of differing lengths (i.e. 'doses') with psychodynamic psychotherapy. Three measures of psychopathology were completed at assessment and at subsequent eight-session intervals until the conclusion of treatment. Each patient received a 3-month follow-up appointment, at which time the measures were again completed. Three treatment duration groups were subsequently constructed and compared via ANOVA: eight sessions (n = 8), 16 sessions (n = 5) and 24 plus sessions (n = 7). Results Results were supportive of a dose-effect relationship, in that outcomes were generally equivalent regardless of treatment duration. Conclusion In short, most change appears to occur in the first eight sessions of treatment, with subsequent outcomes trailing off over time. The clinical implications of the study are discussed in the context of the methodological limitations identified.