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Age-Related Differences in Adaptive Functioning in Hospitalized Children with ASD: Identifying Subgroups at Risk for Functional Decline
Approximately 30% of youth with autism spectrum disorder (ASD) experience a marked decline in adaptive functioning during adolescence. However, characteristics defining this vulnerable subgroup are not well understood, including whether age-related declines in adaptive functioning are apparent for males and females equally. Identifying risk factors for declines in adaptive functioning are necessary given that lower adaptive functioning is associated with increased risk for internalizing disorders, psychiatric hospitalization, higher healthcare costs, and decreased capacity for independent living in adulthood.
Objectives:
1) Examine cross-sectional associations between age and adaptive functioning in a large sample of psychiatrically hospitalized male and female youth with ASD; and 2) Evaluate moderators of the age-adaptive functioning association as a first step toward identifying subgroups for whom adolescence may be a particularly vulnerable period of development.
Methods:
Participants were 450 children (79.6% male) with ASD (confirmed by research-reliable ADOS-2) between the ages of 4 and 21 (mean=12.14±3.15). Participants were recruited from six inpatient units comprising the Autism Inpatient Collection (AIC). Hierarchical linear regression models tested associations between age and subscales of the Vineland Adaptive Behavior Scale III. Models were adjusted for verbal ability, nonverbal IQ, ASD severity, and maternal education (as an index of socioeconomic status). Finally, each covariate was further examined as a moderator of associations between age and adaptive functioning. To account for multiple comparisons, only p-values <0.01 were considered statistically significant.
Results:
In fully adjusted models, age was negatively associated with communication skills (β=-0.120, p=0.001), activities of daily living (ADLs) (β=-0.178, p<0.001), and socialization (β=-0.256, p<0.001; Figure 1). The main effect of age was driven by males as age was unrelated to adaptive functioning in females after adjusting for covariates. In males, the greatest difference in adaptive functioning was between those <12 and ≥12 in all domains: communication (partial ɳ2=0.098), ADLS (partial ɳ2=0.109), and socialization (partial ɳ2=0.146). In females, the greatest difference in adaptive functioning was between those <14 and ≥14 in communication (partial ɳ2=0.054) and ADLS (partial ɳ2=0.111), and between those <12 and ≥12 in socialization (partial ɳ2=0.070). No variables moderated associations between age and adaptive functioning in males. In females, associations with age were significantly stronger for those who were minimally verbal relative to fluently verbal in each domain of adaptive functioning: communication (β=0.798, p=0.007; ΔR2=.046), ADLs (β=0.914, p=0.006; ΔR2=.059), and socialization (β=1.431, p<0.001; ΔR2=.148).
Conclusions:
These cross-sectional findings suggest that failure to meet age-expected gains in adaptive functioning increased with age in males only, with 12 years old as a potential age of onset. Because ASD samples are predominantly male (representative of the ASD population), previous reports of an adolescent-decline in adaptive functioning may have been driven by male participants. In females, failure to meet age-expected gains in adaptive functioning may be most evident for those with verbal communication deficits. Longitudinal studies are needed to evaluate predictors of change in adaptive functioning over the course of development and identify mechanisms by which the transition into adolescence may compromise adaptive functioning in youth with ASD.