Subjects in the ADHD and CON groups were screened for prenatal alcohol exposure and were only included if exposure levels were less than minimal exposure, defined as no more than one drink per week on average and never more than 2 drinks on a single occasion throughout gestation. Control and ADHD subjects were recruited to match the AE subjects recruited at that site. Exclusion criteria for all groups were: history of significant head injury or loss of consciousness > 30 minutes, non-fluent speaker of English (U.S. sites) or Afrikaans (South African site), inability to participate due to psychiatric or physical disability, evidence of other known causes of mental deficiency (e.g., congenital hypothyroidism, or genetic disorders), adoption from abroad after the age of 5 years old or less than 2 years before assessment, or any missing neuropsychological test data (Mattson et al., 2010a).
