Indeed, the epidemiological analyses of Swedish population data suggest some degree of clinical and/or etiological heterogeneity. ADHD was associated with comorbid diagnoses of developmental conditions in both sexes. The strength of association was greater in female individuals for ASD, congenital malformations, and (to a lesser extent) mild ID, but it was similar for both sexes for motor problems, epilepsy, and chromosomal abnormalities. There are several possible explanations for these findings.
