Moving on to consider ADHD (in childhood and adulthood), Retz et al.32 focused on the moderated effects of an adverse childhood environment in their study of 184 male delinquents who averaged 34 years of age. Using a retrospective assessment of childhood ADHD as well as of early adversity, but a clinical interview to assess functioning in adulthood, these investigators detected a crossover interaction with respect to the persistence of ADHD over time. Compared with l/l genotypes, individuals with ‘s' alleles had more and less persistent ADHD, depending on whether or not, respectively, they experienced an adverse early environment.
