Intelligence Profiles in Children and Adolescents with 22q11 Deletion Syndrome with and without Psychopathology

Background: In patients with 22q11 deletion syndrome (22q11DS) neural developmental patterns are found that seem to be related to a greater vulnerability for the development of psychopathology. High incidence of Autism Spectrum Disorders (ASD) is frequently reported and 25-30% of patients develop psychotic disorders in particular schizophrenia. Some studies report that girls often outperform boys, and younger children show higher intelligence scores than older patients. These findings suggest that gender and age may affect cognitive variability in patients.  Studies so far are inconclusive in this regard and focused mainly on intelligence profiles on full-scale level or differences between verbal and performance intelligence. Possibly, these cognitive differences are associated with variable vulnerability for psychiatric disorders in these patients.

Objectives:  To perform an in depth analysis of intelligence profiles in children and adolescents with 22q11DS and investigate the influence of gender, age and psychopathology.

Methods:  Intelligence assessment of sixty children and adolescents aged 9 to 18.5 years using age appropriate Wechsler scales of intelligence as well as psychological assessment, using standardized interview methods to evaluate psychopathology.

Results:  Significant higher intelligence scores were found on Full Scale IQ, Verbal Comprehension and Processing Speed for female patients as compared to male patients. On a subtest level these differences were also found on three out of twelve subtests. Children showed also higher FSIQ and Processing Speed scores as compared to adolescents and performed also better on three of the twelve subtests. When comparing patients with and without psychopathology a significant interaction between presence of Autism Spectrum Disorders and age was found. In patients with ASD relative comparable FSIQs were found in children as well as in adolescents, whereas in patients without ASD a higher FSIQ was found in children while a lower FSIQ was found in adolescents. 

Conclusions:  Findings highlight the heterogeneity of the 22q11DS population as well as the importance of investigating intelligence on multiple levels.  Processing Speed appeared to be more impaired in boys as compared to girls and older patients also had more difficulties with tasks requiring this skill. The age-associated differences found between patients with and without ASD suggest different developmental cognitive trajectories for these subgroups of patients. These findings provide new perspectives on investigating the relation between cognitive functioning and psychopathology in a developmental context in patients with 22q11DS.