Abstract
This study used a twin cohort to investigate the association of autism spectrum disorder (ASD) and autistic traits with somatic health. A total of 344 twins (172 pairs; mean age 15.56 ± 5.62 years) enriched for ASD and other neurodevelopmental conditions were examined. Medical history and current physical problems were collected with a validated questionnaire to determine twin’s somatic health. The Social Responsiveness Scale (SRS-2) was used to measure the participant’s severity of autistic traits. Identified somatic health issues with significant within-twin pair differences were tested in relation to both ASD diagnosis and autistic traits in a co-twin control model. Twins with ASD exhibited more neurological and immunological health problems compared to those without ASD (p = 0.005 and p = 0.004, respectively). The intra-pair differences of neurological conditions and SRS-2 score were significantly correlated in monozygotic twins differing for autism traits (r = 0.40, p = 0.001), while the correlation was not found for immunological problems. In addition, a conditional model for analysis of within-twin pair effects revealed an association between neurological problems and clinical ASD diagnosis (Odds ratio per neurological problem 3.15, p = 0.02), as well as autistic traits (β = 10.44, p = 0.006), after adjusting for possible effects of co-existing attention deficit hyperactivity disorder and general intellectual abilities. Our findings suggest that neurological problems are associated with autism, and that non-shared environmental factors contribute to the overlap for both clinical ASD and autistic traits. Further population-based twin studies are warranted to validate our results and examine in detailed the shared genetic and environmental contributions of neurological problems and ASD.
Highlights
Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by childhood onset heterogeneous alterations of social communication and interaction alongside repetitive, restricted behaviors and interests causing functional impairment (American Psychiatric Association 2013; Bölte et al 2019a)
There was no difference found for infectious diseases and gastrointestinal problems between participants diagnosed with ASD and non-ASD twins
Comparisons within pairs between MZ twins discordant for ASD diagnosis and matched TD controls revealed that twins with ASD had significant more neurological health problems than their co-twins and controls (F = 6.81, p = 0.002), while there was no difference between typically developing co-twins and controls
Summary
Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by childhood onset heterogeneous alterations of social communication and interaction alongside repetitive, restricted behaviors and interests causing functional impairment (American Psychiatric Association 2013; Bölte et al 2019a). Higher prevalence of somatic complications in ASD suggests the possibility of an underlying genetic and/ or environmental perturbation involving multiple systems that impact on the likelihood of the emergence of both ASD and somatic health issues. If this is true, autistic individuals with co-occurring somatic conditions could be considered to qualify as stratification subgroups, where targeted biological intervention might be meaningful and realistic (Doshi-Velez et al 2014; Loth et al 2016). Except for some specific genetic disorders and findings of gene pleiotropy (Cohen et al 2005; Vorstman et al 2017), the mechanisms underlying the comorbidity between somatic health issues, ASD and autistic-like behaviors remain unclear
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