Nonverbal and verbal learning: a comparative study of children and adolescents with 22q11 deletion syndrome, non-syndromal Nonverbal Learning Disorder and memory disorder.

The 22q11 deletion syndrome (DS) is a common genetic disorder, and a Nonverbal Learning Disorder (NLD) is considered as a predominant part of the phenotype. The focus of our study was to investigate the role of learning in this NLD characteristic. We compared results of children and adolescents with 22q11 DS; with non-syndromal NLD and with memory disorders on multi-trial verbal and nonverbal learning tests. Better verbal and worse nonverbal IQs were significantly discrepant for the 22q11 DS sample and for the NLD sample; the memory sample had a FS-IQ in the normal range with lower verbal IQ. General IQ was lowest for the 22q11 DS group. Similar differences in normal verbal and worse nonverbal learning resulted for the 22q11 sample and NLD-sample, while memory sample showed low performances on both tasks. Error analysis in the visual learning task indicated that lacking integration of visual-spatial information affected impaired visual memory performances in 22q11 DS and NLD. Our results reflected a common neurological basis with visual-spatial and visual memory deficits in NLD and in the 22q11 DS sample. To further investigate the issue of cross modal novelty learning deficits we recommend the use of abstract verbal learning material.