Neuropsychological profile of adults with Down syndrome and moderate intellectual disability

The neuropsychological profile of individuals with Down syndrome (DS) has been described as being characterized by dissociations between verbal and visual abilities, as well as between verbal comprehension and production abilities (higher visual than verbal abilities and higher verbal comprehension than verbal production abilities). However, the studies that reached these conclusions based these conclusions mainly on inter-group differences in children but not on intra-group differences.

The study explores dissociations in adults with DS, taking inter-group and intra-group differences into account.

The sample was composed of 40 adults with DS and 38 adults with moderate intellectual disability (ID) but without DS, matched for chronological age, sex, and intellectual level.

The participants with DS, unlike the other group, exhibited similar performance in their verbal and visual abilities, as well as in their verbal comprehension and production abilities (intra-group differences). In addition, they showed worse performance in verbal general measures and verbal comprehension abilities but similar performance in visual general measures and verbal production abilities (inter-group differences) compared with those without DS with similar intellectual levels on standardized measures.

The observed intra-group differences highlight that a lack of dissociation between verbal and visual abilities, as well as between verbal comprehension and production abilities, seems to be a specific feature of adults with DS.