Meta-analysis of the effectiveness of individual intervention in the controlled multisensory environment (Snoezelen®) for individuals with intellectual disability

Background: The Snoezelen® is a multisensory intervention approach that has been implemented with various populations. Due to an almost complete absence of rigorous research in this field, the confirmation of this approach as an effective therapeutic intervention is warranted. Method: To evaluate the therapeutic influence of the Snoezelen® approach. Twenty-eight relevant articles relating to individual (one-to-one) Snoezelen® intervention with individuals with intellectual and developmental disabilities (IDD) were reviewed. A meta-analysis regarding the significance of the reduction of maladaptive behaviour and the enhancement of adaptive behaviour was implemented. An analysis of standardised mean differences was used through the use of fixed effect models. Results: The primary finding was that the Snoezelen® approach, when applied as an individual intervention for individuals with IDD, enabled significant and large effect size in adaptive behaviours, with generalisation to the participants' daily life. Conclusions: Weaknesses in the examined research methodologies, the heterogeneity between research designs, the small number of available research projects, and the small number of participants in each research project, prevent a confirmation of this method as a valid therapeutic intervention at this time.