Relationship Between Mental Age and Everyday Adaptation Reported By Teachers in Low Functioning Individuals with and without ASD

Background:

Adaptive skills have been defined as key to the later outcome of individuals with ASD (Sparrow et al. 2005). However, individuals with ASD experience difficulties in everyday life regardless of cognitive ability (Black et al. , 2009). Contrary to TD, where IQ is closely related to adaptive skills, in ASD there seem to be a discrepancy between measures (Bolte & Poustka, 2002). In the case of individuals with Intellectual disability (ID) associated to ASD, IQ has been reported higher than adaptive skills (Perry et al., 2009) although adaptive skills remain more impaired than in the case of individuals with ID alone (Bolte & Poustka, 2002). In terms of mental age, individuals with ASD+ID present a distinctive adaptive profile (high motor skills, followed by daily living communication, and social skills; Perry et at., 2009). Although this profile was also reported for ID alone individuals, authors found significant differences between groups, concluding that ASD+ID individuals are socially impaired on adapting to everyday life over and above individuals of similar mental ages but not ASD. Teachers are a valuable source of information as the school is a very rich socio and educational environment. To date, no study has explored IQ/Mental Age in relation to adaptive skills as reported by teachers.

Objectives:

To examine the intelligence and developmental level of individuals with ID, with and without ASD, in relation to adaptive skills as reported by teachers reports. To explore whether the profile described by Perry and colleagues (2009) is replicated in relation to low‑functioning individuals.

Methods:

Data was gathered from a sample of 33 individuals with ASD+ID and 37 individuals with ID alone (age range 5 -17) matched in Performance and Verbal MA, obtained from the Ravens Coloured Progressive Matrices (RPCM), and the British Picture Vocabulary Scales (BPVS) respectively. Adaptive skills were measured using the Vineland Adaptive Behaviour Skills Teacher Rating Form (VABS, Sparrow et al., 2006).

Results:

IQ comparisons were not possible due to the high number of individuals with IQ below basal scores (n = 20), or who fell outside the IQ age range (n = 17). VMA correlated significantly in ID with the social sub-domains of the VABS (all r > .53; all p < .001), but only interpersonal relationships for individuals with ASD+ID (r = .54, p = .001). PMA correlated significantly in ID with Living Skills School and socialization interpersonal (r > .64, p < .001) but not in ASD+ID.

Conclusions:

Results show a very distinct profile in the adaptive skills of individuals with ID with and without ASD. In ID, VMA play an important role on adaptive skills in general, while academic, school, and social interpersonal relationships are also mediated by PMA. In the case of ASD+ID, mental age seemed to be associated with academic skills, and VMA specifically to the relationships with others. The results here presented show how the socialization impairment characteristic of ASD may result in a significant adaptability deficit – measured from teacher ratings - beyond their intellectual disability.