Developmental Variability in Autism Across 17 000 Autistic Individuals and 4000 Siblings Without an Autism Diagnosis

Abstract

This study characterizes variability in the age at which autistic individuals attain key developmental milestones compared with siblings who do not have an autism diagnosis.

Heterogeneity thwarts autism explanatory power: A proposal for endophenotypes

“…Introduction: Heterogeneity thwarts autism explanatory power: Can transdiagnostic behavioral endophenotypes help? patterns, comorbidities, and biomarkers (3)(4)(5)(6)(7). Casanova et al (8) asserted that, "The diagnostic boundaries of the behavioral phenotype that define ASD are fairly broad due to the large variability that is observed in symptom types, onset, and severity.…”

“…The efforts for reducing autism heterogeneity-creating prototypical autism, excluding moderate-to-severe autism symptoms, creating subgroups, and increasing sample sizes-have not yet been effective in reducing heterogeneity. Thus, heterogeneity remains an unresolved problem (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Moreover, as discussed previously, establishing the unitary DSM-5 ASD diagnosis has not reduced autism heterogeneity.…”

“…Three influential theories of the cause of social impairment are unlikely to be a sound basis for the discovery of constructs for endophenotypes: ( 1 ) weak central coherence, ( 2 ) impaired Theory of Mind (ToM), and ( 3 ) impaired executive function. Bottema-Beutel et al ( 66 ) conducted a meta-analysis of these three theories thought to index eight social skills: imitations; responding to and initiating joint attention; pretend play; executive functions; ToM; central coherence; and visual fixation to social stimuli.…”

“…Rosello et al reviewed several subgroup studies and reported three general subgroups: ( 1 ) severe expression of all autism diagnostic symptoms; ( 2 ) moderate social impairment with few RRBs; and ( 3 ) a low level of social impairment with a high level of RRBs ( 51 ). The three levels of social impairment—severe, moderate, low—may reflect an underlying continuous distribution of social impairment.…”

“…Morris et al ( 1 ) stated that psychiatric diagnoses “have been reified—seen as “real entities” —when in reality they are not natural kinds” (p. 2). Autism is not a unitary biological entity or natural kind ( 2 ) because individuals diagnosed with autism have many varied and complex biological causes for their symptoms, and vary in symptom patterns, comorbidities, and biomarkers ( 3 – 7 ). Casanova et al ( 8 ) asserted that, “The diagnostic boundaries of the behavioral phenotype that define ASD are fairly broad due to the large variability that is observed in symptom types, onset, and severity.…”