Background: Although diagnosis and identification of IDD is improving, adolescents with IDD receive limited attention in research, particularly concerning their psychosocial development. Measures developed and normed with typically developing populations may not be appropriate for IDD populations and may result in biased assessment.
Aim: This study aimed to develop and validate modified psychosocial development assessments for adolescents with intellectual and developmental disabilities (IDD), addressing the absence of such assessments.
Method: It involved two phases: modifying existing instruments and validating the revised versions. Four stakeholder groups participated: adolescents with IDD, parents, and scholars in adolescent developmental and disabilities. Validation included two groups: neurotypical adolescents completing both measures and IDD adolescents completing modified measures.
Results: Confirmatory factor analyses identified the need to adjust or eliminate scales for better understanding by individuals with IDD. The modified instruments provided suitable measures for assessing psychosocial development in adolescents with IDD.
Discussion: All the scales allowed for accommodation toward comprehension for those with IDD except for identity formation. Further work is needed to understand the challenges associated with assessing identity formation in adolescents with IDD. The active involvement of and participation from adolescents with IDD and their parents in this research was paramount to understanding their comprehension and needs.
Conclusion: This study highlights the importance of tailored assessments for accurate measurement of IDD individuals' development, benefiting the assessment of all adolescents.
Keywords: adolescents; instrument validation; intellectual and developmental disabilities; modified assessments; psychosocial development.
© 2023 Foundation for Professionals in Services to Adolescents.