ebook_ADHD2019_engl.

For decades, many scientists have been searching for the etiology of attention defi- cit hyperactivity disorder (ADHD). This search has been motivated by the belief that if we can find the causes of the disorder we may be able to improve our unders- tanding of ADHD psychopathology and discover more accurate treatments or even prevent the onset of this frequently disabling condition. We will consider two sour- ces of etiology: the DNA variants coded in our genome and shared and non-shared environment factors that impact the developing brain. GENETIC CAUSES OF ADHD EPIDEMIOLOGY The first evidence for the heritability of ADHD comes from several studies of families. This work showed that the siblings, mothers and fathers of children with ADHD were at increased risk for the disorder. Figure 1.1 shows examples of early family studies. In Figure 1.1A, the risk to siblings found by Manshadi and col- leagues 1 is especially interesting because the ADHD patients in that study were adults. These studies were the first evidence that ADHD might have a genetic UNDERSTANDING THE ESSENTIALS OF THE ETIOLOGY OF ADHD Stephen V. Faraone Lino Palacios Cruz Francisco R. de la Peña Olvera 1