An important strength of this study is that the H/I group was not restricted to those meeting diagnostic criteria for ADHD. This may have enhanced the generalizability of this group to a wider population of children who are symptomatic without necessarily meeting formal diagnostic criteria. Further, the use of dimensional measures of ADHD allowed for a more nuanced assessment of variations in symptom severity over time; this is important considering that these symptoms are observed along a continuum, with those who are diagnosed having the most symptoms (Lubke, Hudziak, Derks, van Bijsterveldt, & Boomsma, 2009).
