ebook_ADHD2019_engl.

46 Rohde, Buitelaar, Gerlach & Faraone CRITERION B – AGE-OF-ONSET ADHD has been traditionally conceptualized as a neurodevelopmental disorder. Thus, it is not surprising that age of onset in early childhood emerged as a key element in the definitional criteria for the disorder. In the past four decades, ex- perts behind diagnostic manuals have struggled with the lack of evidence to define an accurate threshold for chronological age beyond which symptoms should no longer be considered part of the ADHD syndrome. 2,4,7 Based solely on clinical wisdom, DSM-III 8 introduced ADHD criterion B, which required symptoms to be present before the age of 7 years, and DSM-IV-TR 9 added that impairment must also be present by this same age. A number of studies have now challenged the utility and validity of this crite- rion B. The DSM-5 scientific committee decided to change the criterion to requi- re several symptoms before age 12, based on evidence that this threshold would capture almost every case presented in childhood, without raising significantly the prevalence rate. However, recent evidence suggests that the increase in ADHD prevalence rates might not be as insignificant as previously thought with this mo- dification in age-of-onset criterion. 10 It is important to note that DSM-5 specifies that the age-of-onset criterion re- fers to symptoms and not necessarily impairment, as was the case for DSM-IV. The reason for this is that ADHD is a highly comorbid disorder in clinical settings and disentangling the source of impairment and its age-of-onset is at best difficult and frequently unfeasible. Impairment may arise later in life when, for example, parental scaffolding is no longer available. More recently, several studies with po- pulation samples challenged the threshold for age-of-onset at 12 years of age sug- gesting the possibility of substantial number of cases with late-onset ADHD after 12 years of age. This is still a controversial area where more research is clearly needed. 11 Link in this https://www.youtube.com/ watch?v=w4t4JFKDD6s