Aetiology for the covariation between combined type ADHD and reading difficulties in a family study: the role of IQ.
This study evaluated the internal structure and convergent and discriminant evidence for the Colorado Learning Difficulties Questionnaire (CLDQ), a 20-item parent-report rating scale that was developed to provide a brief screening measure for learning difficulties. CLDQ ratings were obtained from parents of children in 2 large community samples and 2 samples from clinics that specialize in the assessment of learning disabilities and related disorders (total N = 8,004). Exploratory and confirmatory factor analyses revealed 5 correlated but separable dimensions that were labeled reading, math, social cognition, social anxiety, and spatial difficulties. Results revealed strong convergent and discriminant evidence for the CLDQ Reading scale, suggesting that this scale may provide a useful method to screen for reading difficulties in both research studies and clinical settings. Results are also promising for the other 4 CLDQ scales, but additional research is needed to refine each of these measures.