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There is evidence that children with neurodevelopmental disorders may exhibit atypical responses to stress and alterations in concentrations and diurnal secretion of stress hormones. We assessed diurnal profiles and stress responses of salivary cortisol and alpha-amylase (sAA) in children with attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and specific learning disorder (SLD) compared to typically developing children (TD). A total of 157 children of both sexes, aged between 6 and 12 years old, took part in the study distributed into four groups: ADHD (N = 34), ASD (N = 56), SLD (N = 43) and TD (N = 24). Salivary samples were collected at three time points during a day, as well as before and 5 min after an academic performance test and a moral cognition task. ADHD children had lower evening and diurnal sAA levels, adjusted for age. Also, ASD children showed lower diurnal sAA secretion, adjusted for age. The mean percentage change for salivary cortisol and sAA after both tests did not differ between the groups. In conclusion, we demonstrated alterations in diurnal autonomic functioning in children with ADHD and ASD, while hypothalamic–pituitary–adrenal axis functioning did not differ between the clinical and the comparison groups. © 2020 John Wiley & Sons Ltd.

Prospective studies indicate that the exposure to organochlorine pesticides (OCPs) during fetal life, infancy, and early childhood may be associated with features of neurodevelopmental disorders in children. However, few studies have investigated the concentrations of serum OCPs in children with categorically diagnosed neurodevelopmental disorders. The aim of this study was to assess the concentrations and detection rates of dichlorodiphenyltrichloroethane (DDT) metabolites, hexachlorocyclohexane (HCH) isomers, cyclodienes, and methoxychlor in serum samples of children with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and specific learning disorder (SLD), all of normal intelligence, compared to typically developing controls (TD). In total, 114 schoolchildren, aged 6–13 years old, were assessed and distributed into four groups: ASD (n = 39), ADHD (n = 21), SLD (n = 32), and TD (n = 18). Each clinical group was compared to the TD group. Concentrations of serum OCPs were determined by gas chromatography and are presented as ng/g lipid. Concentrations of β-HCH, the sum of HCH isomers, and o,p′-DDD were significantly higher in ASD children: ASD vs. TD (mean ± SD): 10.5 ± 7.7 vs. 6.1 ± 4.0, (p = 0.049); 12.0 ± 10.3 vs. 6.6 ± 4.0, (p = 0.025); 7.4 ± 6.5 vs. 2.8 ± 2.3, (p = 0.0019), respectively. The detection rates of p,p′-DDT, at least one substance from DDTs detected, and the cyclodiene heptachlor epoxide, were significantly lower in the ASD group: ASD vs. TD: 12.8% vs. 38.9%, (p = 0.037); 69.2% vs. 94.4%, (p = 0.044); 10.3% vs. 38.9%, (p = 0.026), respectively. No significant differences between the ADHD or SLD groups and the TD group were observed. We demonstrated higher serum concentrations and lower detection rates of selected OCPs in ASD than TD children. Our results add to potential neurodevelopmental concerns surrounding OCPs and provide evidence of specificity in the relations between HCHs and ASD. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.