Autism Severity and Its Impact on Cognitive Development in Young Children with Autism

Background: Autism is a complex neurobiological disorder. Its core deficits of communication, social interaction and restricted/repetitive behaviors have a tremendous impact on how individuals function and cope with various demands over the life span. Key social communication deficits in children with ASD are in the areas of joint attention (coordinating attention from object to person), reciprocal interactions such as giving, taking turns and sharing (Kasari, Freeman & Paparella, 2006). Motor and sensory repetitive behaviors (RSBs) have been associated more with younger ages (Militerni et al., 2002), its impact on cognitive abilities needs further investigation.

Objectives: The purpose of this study is to examine how social communication deficits and RSBs impact cognitive development in young children with autism. The information thus obtained would be critical to determining specific areas for intensive early intervention.

Methods: This analysis was conducted on 56 children diagnosed with Autism based on DSM IV criteria. The sample included children ranging from 2.5 years to 6.0 years. Of these participants, 47 were males and 9 were females. Cognitive functioning was assessed using the 4 core subtests of the lower preschool level of the Differential Ability Scales (DAS). The Preschool level is usually for ages 2:6 to 3:5, but complete norms are available up to age 6:11, which allows for lower-ability 6-year-olds to be tested at a more appropriate developmental level. The 4 core subtests comprise of Block Building (visual-perceptual matching), Naming Vocabulary (expressive vocabulary), Verbal Comprehension (receptive language) and Picture Similarities (non verbal reasoning). Autism severity was assessed using the Autism Diagnostic Observation Schedule (ADOS; Lord et al., 1999; Lord et al., 2000). Module 1 or 2 was used depending on individual child’s expressive language abilities. The ADOS variables of interest were total scores for communication (directing facial expressions, vocalizations to others, conversation), reciprocal social interaction (eye contact, initiating and responding to joint attention, shared enjoyment), Play (functional and imaginative play) and Stereotyped behaviors /Restricted Interests (unusual sensory interests, repetitive interests, complex mannerisms).

Results: Multiple regression analysis was used to determine, from five predictor variables (severity of symptoms as measured by the ADOS) those that would be most predictive of the dependent variable (DAS subtest). Four separate analyses were conducted using forward method of entry (with criteria of p < .05 to enter variables) on each of the four core DAS subtests. Correlations showed that ADOS social interaction was significantly (p < .05) related to DAS block building ability scores. ADOS socialization and communication scores was significantly (p < .05) related to DAS Naming ability scores. ADOS stereotypical behavior scores was significantly (p < .05) related to DAS Picture Similarities ability scores. ADOS play score was significantly (p < .05) related to DAS Verbal Comprehension ability scores.

Conclusions:

Results clearly demonstrate that core deficits in autism impact cognitive development in the areas of imitation, visual perceptual matching, non verbal reasoning and receptive expressive language skills. Interventions in young children with autism need to focus on preverbal/verbal language skills, play and social interactional skills.