Children with Autism Spectrum Disorders and ‘Special Abilities' Represent a Unique Clinical Subgroup

Background:  Increased incidence of ‘special abilities’ in autism spectrum disorders (ASD) in comparison to other neurodevelopmental disorders has been described.  Only a few studies have addressed the phenomenon of ‘special abilities’ in ASD, their frequencies, types, and relations to specific symptoms of autism.

Objectives:  

1. to assess the prevalence and distribution of different types of ‘special abilities’ in a large cohort with ASD. 2. To compare children with and without ‘special abilities’ in autism severity, sensory modulation problems severity; adaptive skills abilities; developmental regression; head circumference and family variables (parental education; ASD in the family). 3. To examine whether child characteristics (‘special abilities’; age; gender; autism severity) and parental education can predict adaptive skills functioning.

Methods:  

From a cohort of 550 children who came to a tertiary autism center and were diagnosed with ASD, only 398 children that were in the age range of 24-84 months, were included in the study. A score of 2 on one of the 'Special isolated skills' items (visuospatial, memory, musical, drawing, reading and computational skills) from the Autism Diagnostic Interview-Revised (ADI-R) was used as a criteria for inclusion in the ‘special abilities’ group. Pair-matched control group (N=79) without ‘special abilities’ was selected from the entire ASD group. Medical, developmental familial histories were obtained from the parents. Evaluations of autism severity, sensory problems, and developmental regression were based on the ADI-R, Autism Diagnosis Observation Schedule (ADOS) and the new ADOS severity scale. Adaptive skills were assessed using the Vineland Adaptive Behavior Scales. A neurological assessment including head circumference measure was conducted by a pediatric developmental neurologist.

Results:  

Of the 398 children, 112 (28%) were identified with ‘special abilities’. Of this group, 40% had memory skills, 24 %  music skills, 21.4%  visuospatial, 20%  reading skills, 6.8% computational skills and 2.6% drawing skills. The 'special abilities' group had significantly better functioning in adaptive communication, socialization and daily living skills domains in comparison to the control group.  The two groups did not differ in the overall autism severity score, but the 'special abilities' group had significantly less severe communication (ADOS A) and Social-reciprocal (ADOS B) deficits than the control group.  The 'special abilities' group had significantly less severe stereotypic repetitive behaviors and sensory modulation problems than the control group using both the ADI and ADOS relevant items. Head circumference in the control group was significantly smaller than in the 'special abilities' group. Paternal and maternal education of the 'special abilities' group was significantly higher than that of the control group.  No differences were noted in developmental regression and familial history of ASD.  In our prediction model of adaptive skills' functioning, autism severity contributed 29% and ‘special abilities’ added 28% to the explained variance.

Conclusions:  

‘special abilities’ are very common in ASD.  The 'special abilities' group represents a special subgroup with less severe autism symptoms and sensory modulation problems, better adaptive skills functioning, greater head circumference and higher parental education.  Future studies should focus on genetic and imaging research that will shed light on the origin of these ‘special abilities’.