ABSTRACT
Children with 22q11.2 deletion syndrome (22q11DS; velo-cardio-facial-syndrome) are at risk for the developmental disorders, attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). In this study, the relation between executive functioning (EF) and the severity of ADHD and ASD symptoms is examined, since EF is known to be important in relation to emotional and behavioral problems. The participants consist of 58 children (38 females) with a mean age of 13.5 years (SD 2.6). Standardized assessment was used to evaluate the severity of ASD and ADHD symptomatology. The major aspects of EF, i.e., cognitive flexibility, inhibition, sustained attention, distractibility, working memory and reaction speed, were evaluated. The profile of EF in 22q11DS was found to be characterized by weaker performance compared to the norms on all subdomains of EF. Poor cognitive flexibility and inhibition, as well as high distractibility, were found to be related to more severe ASD symptoms, while poor quality of sustained attention and high distractibility were found to be related to more severe ADHD symptoms. It is concluded that children with 22q11DS experience impairments in EF, and that the degree of impairment on specific EF subdomains is related to the severity of ASD and/or ADHD symptomatology. These results may help in defining the mediating role of neurocognitive dysfunctions in the development of social and behavioral problems in 22q11DS.
Subject(s)
Attention Deficit Disorder with Hyperactivity/diagnosis , Autism Spectrum Disorder/diagnosis , DiGeorge Syndrome/complications , Executive Function/physiology , Adolescent , Attention Deficit Disorder with Hyperactivity/psychology , Autism Spectrum Disorder/psychology , Chromosomes, Human, Pair 22 , DiGeorge Syndrome/pathology , Female , Humans , Male , Neuropsychological TestsABSTRACT
The association between the 22q11.2 deletion syndrome (22q11DS) and psychiatric disorders, particularly psychosis, suggests a causal relationship between 22q11DS genes and abnormal brain function. The genes catechol-O-methyl-transferase (COMT) and proline dehydrogenase both reside within the commonly deleted region of 22q11.2. COMT activity and proline levels may therefore be altered in 22q11DS individuals. Associations of both COMT(158) genotype and elevated serum proline levels with abnormal brain function have been reported. Fifty-six 22q11DS children and 75 healthy controls were assessed on physiological measures of brain function, including prepulse inhibition (PPI) of startle, P50 auditory sensory gating and smooth pursuit eye movements (SPEM). COMT(158) genotype and plasma proline levels were determined in the 22q11DS children. We hypothesized an interaction between the COMT(158) genotype and proline, predicting the strongest negative effect of high proline on brain function to occur in 22q11DS children who are carriers of the COMT(met) allele. Of the three physiological measures, only SPEM and PPI were abnormal in the patient sample. With regard to the SPEM performance, there was a significant interaction between the COMT(158) genotype and proline level with significantly decreased SPEM performance in children with high plasma proline levels and the low activity COMT(met) allele. A similar interaction effect was not observed with regard to PPI. These findings are consistent with a model in which elevated proline negatively affects brain function by an increase in dopamine in the prefrontal cortex. 22q11DS patients with low dopamine catabolic capacity are therefore especially vulnerable to this functional disruption.
