Harmonized phenotypes for internalizing problems and ADHD

The aim of this study is to harmonize questionnaire item data with an objective of having one phenotype, that is comparable across various cohorts. Our focus is on internalizing problems and ADHD symptoms. We used a total of... [ view full abstract ]

The aim of this study is to harmonize questionnaire item data with an objective of having one phenotype, that is comparable across various cohorts. Our focus is on internalizing problems and ADHD symptoms. We used a total of 1330, 10-year-old children data available in the Western Australian Pregnancy Cohort study (RAINE) dataset, with complete data on the Child Behaviour Checklist (CBCL) and the Strength and Difficulties Questionnaire (SDQ). We carried out a varimax factor analysis on all items to identify relevant dimensions. We found 2 dimensions (‘emotional problems’ and ‘ADHD’) with high CBCL and SDQ loadings. We carried out an Item Response Theory (IRT) analysis using a Generalized Partial Credit Model to investigate the psychometric quality of these two dimensions. The results showed that particular subsets of CBCL and SDQ items can be used together but also separately to measure emotional problems and ADHD. We recommend to use these sets of items, rather than the original subscales, in order to work with commensurate phenotypes across various research groups.