Parent-Reported Developmental Regression in Autism Spectrum Disorder: Epilepsy, Intellectual Disability, Schizophrenia Symptoms, and Special Education

Background:  A minority of youth with autism spectrum disorder (ASD) are reported to experience loss of pre-acquired skills during the preschool years. A recent meta-analysis puts the rate of developmental regression at 32% with a mean onset of 1.78 years (Barger, Campbell, & McDonough, 2013). Among the most consistent findings characterizing this ASD subgroup are greater severity of intellectual and ASD symptoms relative to non-regressed peers. However, little research has addressed the association of non-ASD DSM-defined psychiatric comorbidity with developmental regression, plausible particularly as it pertains to schizophrenia spectrum disorder symptoms (SSD) given preliminary evidence supporting a clinically relevant sub-group within the broader ASD phenotype (Gadow & DeVincent, 2012).

Objectives:  1. To determine whether a brief parent report of developmental regression provides clinically helpful information about youth who are referred for evaluation in a developmental disabilities outpatient clinic. 2. To examine the association of SSD with developmental regression and explore associations with specific symptoms.

Methods:  Case records for consecutive referrals to a university hospital developmental disabilities clinic were screened for children between 6 and 18 years old at time of evaluation diagnosed with ASD. Caregivers completed ratings of psychiatric symptoms (parents, teachers) and a background history questionnaire (parents). Separate chi-square tests (categorical variables), t tests (continuous variables), and Mann-Whitney Utests (ordinal variables) data were conducted to examine group differences.

Results:  Parents of 48 youth indicated that their child had experienced developmental regression in communication and/or social skills by the age of 36 months; parents of 136 youth reported that their child had not experienced regression. The developmentally regressed group were more likely to have intellectual disability; more severe ASD communication deficits; diagnosis of epilepsy; and to be receiving special education services and in more socially restrictive settings than non-regressed youth (see Figure). Youth in the regressed group were rated by parents as having significantly greater SSD symptom severity (t=2.41, p=.017); however, teachers’ symptom severity ratings did not significantly differ between groups. The regressed group was also more likely to be impaired by SSD symptoms according to both parents’ (χ²=7.66, p=.006) and teachers’ ratings (χ²=6.35, p=.012). Analyses of individual symptoms showed that parents’ ratings for youth in the regressed group were significantly greater than the non-regressed group for disorganized behavior (U=2420.0, p=.018) and avolition (U=2368.0, p=.012).

Conclusions:  The findings support the clinical utility of asking parents about their child’s early developmental history during initial diagnostic evaluations, specifically perception of developmental regression, as a history of regression indicates increased risk for a more impacted clinical course (e.g., intellectual disability, epilepsy, ASD communication deficits, special education, and social exclusion in special services), and owing to its typical age of onset, may be of value in procurement of early intervention. Youth with regression were more likely to experience greater severity of and impairment from SSD symptoms than youth without regression, specifically disorganized behavior and negative symptoms. It is noteworthy that these symptoms, as is the case with developmental regression, correlate with ASD symptom severity whereas positive symptoms and disorganized thinking do not (Gadow, 2013).