Studies of other cognitive abilities have revealed further differences between these groups. In one study of executive function, different patterns of deficit were revealed: although the groups were similar on the Wisconsin Card Sorting Test, only children with FASD displayed overall deficits on letter fluency and a relative weakness on the Trail Making Test–B versus the Trail Making Test–A (Vaurio, et al., 2008). In a study of verbal learning and memory using the CVLT-C, verbal learning was affected in both groups, although in different ways; performance of alcohol-exposed children appears to reflect inefficient encoding of verbal material, whereas performance of children with ADHD is better characterized by a deficit in retrieval of learned material (Crocker, et al., 2011). Children with FASD and ADHD have also been distinguished using measures of mathematics and numerical processing (Jacobson, et al., 2010). Results of this study suggest that mathematics difficulty in children with ADHD might be more related to impairments in general cognitive abilities important for proficient academic achievement whereas children with FASD display a specific impairment in basic numerical processing abilities, such as the ability to mentally represent and manipulate numbers and quantities.
