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High-Risk Siblings with Atypical Developmental Trajectories: Clinical Outcomes at Early School Age
Objectives: To examine clinical outcomes in a group of complex cases ascertained though the prospective longitudinal HR sibling study from 6 to 36 months.
Methods: Six HR siblings with complex clinical presentations in the first 3 years of life (i.e., borderline and fluctuating ASD symptoms) were comprehensively assessed at the age of 4-6 years, using a battery comprised of cognitive, neuropsychological, language, adaptive, social and emotional functioning measures.
Results: Clinician Best Estimate. Four of the six children continued to evidence social pragmatic difficulties at follow-up, but were subthreshold for ASD. One child met criteria for ADHD and Anxiety-NOS. Of the two children who previously received a PDD-NOS diagnosis, one met criteria for ASD and the other showed no evidence of ASD. ASD Symptom Severity. In all but one case, ASD symptom severity declined or remained stable between 3 and 6 years. Level of ASD related symptoms on the ADOS ranged from ‘minimal’ to ‘low’. Infrequently observed were unusual sensory interests, or restricted, repetitive patterns of behavior or interests. Comorbid symptoms. The Early Childhood Inventory-4 revealed clinical or borderline range scores for Generalized Anxiety Disorder, Social Phobia, or ADHD. Two children had elevated global scores on the BRIEF suggesting the presence of executive functioning vulnerabilities. No children had a significant elevation on the Shift scale (assessing flexibility/adaptability), a scale that typically distinguishes children with ASD from other clinical groups. Cognitive functioning. All children were functioning in the average to above average range; in two cases verbal IQ scores exceeded nonverbal IQ scores by at least 1 standard deviation (SD). Language. All children’s core language fell in the average to above average range. In four out of six cases, narrative skills fell at least 1SD below their formal language production. Adaptive Functioning. All but one child had a Socialization score in the ‘Adequate’ range on the Vineland-II. However, examining interpersonal skills, three of the six were functioning below age-based expectations. Social Perception: Scores on measures of affect recognition, memory for faces, and memory for names were lower than cognitive ability by at least 1SD in 50-75% of children.
Conclusions: These preliminary data underscore the complexity of long-term outcomes in HR siblings. A common theme suggests that variability is a defining feature of their presentation as these children evidenced variable developmental trajectories and variable diagnostic outcomes; a co-occurring vulnerability for both ASD symptomatology and other disorders exists on a clinical and also on a subclinical level. This variability highlights the danger of an “averaging artifact” where the pattern detected at a group level does not describe well any single member of the group. Understanding the full range of outcomes among HR siblings in future research, in terms of categorical presentation and functioning along specific dimensions, will be crucial for understanding the risk factors and clinical needs of this unique population.