Association results from logistic regression analysis between reading/spelling difficulties and ADHD symptoms measured by the SDQ-hyperactivity/inattention score.

1refers to the number of individuals with reading/spelling difficulties for whom full phenotypic information was available and who were included in regression analysis.2refers to the number of individuals without reading/spelling difficulties for whom full phenotypic information was available and who were included in regression analysis.3adjusted for gender, age, study and study center.4additional adjustment for parental education, age of mother at birth, daily TV/PC use, single parent and ETS exposure.p-values