2018Alycia Halladay
A conversation with Clare Harrop about autism in boys and girls
Objective: The diagnosis of autism spectrum disorder (ASD) has been found to be remarkably stable but few studies have followed children not initially diagnosed with ASD beyond 3 years of age to examine late or delayed diagnoses. The present study used a prospective familial-risk design to identify children who had undergone multiple comprehensive assessments in preschool and were determined to be negative for ASD only to meet criteria for ASD when tested in middle childhood.
Method: Data were pooled across 3 research teams studying later-born siblings of children with ASD. Fourteen children met inclusion criteria for the late-diagnosed group and were compared with a large sample of high- and low-risk siblings from the same sites who had ASD or typical development (TD) outcomes at 3 years of age.
Results: As a group, the late-diagnosed children scored between the TD and ASD groups on most measures administered at 3 years and differed significantly from the ASD group on most measures. However, there was significant heterogeneity among the late-diagnosed cases. Seven showed very little evidence of ASD in preschool, whereas 7 demonstrated subtle, subthreshold symptomatology.
Conclusion: Some children with ASD might present with a subtle phenotype early in life or show a prolonged time course of symptom development. This emphasizes the need for screening and surveillance schedules that extend past 36 months and continued evaluation of any child who presents with atypical early development and/or high-risk status. The findings also shed light on reasons why the mean age of ASD diagnosis remains older than 4 years.
Keywords: autism spectrum disorder; diagnosis; diagnostic stability.
Prenatal exposure to maternal stress and depression has been identified as a risk factor for adverse behavioral and neurodevelopmental outcomes in early childhood. However, the molecular mechanisms through which maternal psychopathology shapes offspring development remain poorly understood. We applied transcriptome-wide screens to 149 umbilical cord blood samples from neonates born to mothers with posttraumatic stress disorder (PTSD; n = 20), depression (n = 31) and PTSD with comorbid depression (n = 13), compared to carefully matched trauma exposed controls (n = 23) and healthy mothers (n = 62). Analyses by maternal diagnoses revealed a clear pattern of gene expression signatures distinguishing neonates born to mothers with a history of psychopathology from those without. Co-expression network analysis identified distinct gene expression perturbations across maternal diagnoses, including two depression-related modules implicated in axon-guidance and mRNA stability, as well as two PTSD-related modules implicated in TNF signaling and cellular response to stress. Notably, these disease-related modules were enriched with brain-expressed genes and genetic risk loci for autism spectrum disorder and schizophrenia, which may imply a causal role for impaired developmental outcomes. These molecular alterations preceded changes in clinical measures at twenty-four months, including reductions in cognitive and socio-emotional outcomes in affected infants. Collectively, these findings indicate that prenatal exposure to maternal psychological distress induces neuronal, immunological and behavioral abnormalities in affected offspring and support the search for early biomarkers of exposures to adverse in utero environments and the classification of children at risk for impaired development.
Keywords: Autism spectrum disorder; Depression; PTSD; Schizophrenia; Stress response; The Drakenstein Child Health Study; Trauma.
Background: Variability of short-lived urinary pesticide metabolites during pregnancy raises challenges for exposure assessment.
Objectives: For urinary metabolite concentrations 3-phenoxybenzoic acid (3-PBA) and 3,5,6-trichloro-2-pyridinol (TCPy), we assessed: (1) temporal variability; (2) variation of two urine specimens within a trimester; (3) reliability for pesticide concentrations from a single urine specimen to classify participants into exposure tertiles; and (4) seasonal or year variations.
Methods: Pregnant mothers (N = 166) in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) Study provided urine specimens (n = 528). First morning void (FMV), pooled, and 24-h specimens were analyzed for 3-PBA and TCPy. For 9 mothers (n = 88 specimens), each urine specimen was analyzed separately (not pooled) to estimate within- and between-person variance components expressed as intraclass correlation coefficients (ICC). Pesticide concentrations from two specimens within a trimester were also assessed using ICC’s. Agreement for exposure classifications was assessed with weighted Cohen’s kappa statistics. Longitudinal mixed effect models were used to assess seasonal or year variations.
Results: Urinary pesticide metabolites were detected in ≥ 93% of specimens analyzed. The highest ICC from repeated individual specimens was from specific gravity-corrected FMV specimens for 3-PBA (ICC=0.13). Despite high within-person variability, the median concentrations did not differ across trimesters. Concentrations from pooled specimens had substantial agreement predicting exposure categories for TCPy (K = 0.67, 95% CI (0.59, 0.76)) and moderate agreement for 3-PBA (K = 0.59, 95% CI (0.49, 0.69)). TCPy concentrations significantly decreased from 2007 to 2014.
Conclusions: Pooled specimens may improve exposure classification and reduce laboratory costs for compounds with short biological half-lives in epidemiological studies.
Keywords: Exposure; Longitudinal; Pesticides; Pregnancy; Variability.