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Purpose: The aim of the study is to examine (i) if young children with a family history of autism and/or ADHD differ on executive functions and deferred gratification in comparison to peers with no family history of autism or ADHD, (ii) the specificity of these domains in relation to early-life autistic and ADHD symptoms and adaptive functioning, and (iii) if deferred gratification and strong EF skills may function as protective factors in the association between symptoms and adaptive behaviour.

Methods: A total of 77 infant siblings at 3 years of age with a family history of autism only, autism and co-occurring ADHD, or no family history of these conditions (FH-TL) were assessed on behavioural lab-tasks (EF and deferred gratification), parent-rated adaptive behaviour using Vineland, and clinician ratings using ADOS-2 (autistic symptoms) and ADHD DSM-5 symptom rating scale (ADHD RS).

Results: Group comparisons showed that FH-autism and FH-autism + ADHD groups received lower scores on common EF, but not on deferred gratification in comparison to the FH-TL group. Lower levels of deferred gratification related to autistic symptoms, while lower level on EF was specific to ADHD symptoms. Finally, deferred gratification moderated the association between autistic symptoms and adaptive behaviour, in that stronger ability to defer gratification attenuated the association between autistic symptoms and adaptive functions.

Conclusions: These results are in line with the idea that strong ability to inhibit and defer gratification may act as a protective factor for children with a family history of autism and/or ADHD pointing to affective aspects of EF as particularly important.

Autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and developmental language disorder (DLD) are neurodevelopmental conditions (NDCs) that share etiological factors and frequently co-occur. Despite this, they have rarely been studied together?particularly in relation to functional outcomes. In this study, we investigate the association between the developmental pattern of sustained visual attention in infancy and number of diagnoses, and map the clinical profile of 6-year-old children. A cohort of 6-year-olds, originally recruited in infancy due to elevated (n = 42) or low (n =7) likelihood of ASD, were assessed for sustained visual attention, diagnostic outcomes, general adaptive functioning, intellectual abilities, and language skills. Participants were grouped based on the number of NDC diagnoses (ASD, ADHD, DLD, and/or Subthreshold ASD) they received at follow-up. We could not find statistical support for an association between sustained visual attention and number of diagnoses. Findings revealed no significant differences in adaptive functioning, intellectual abilities, or language skills between children with no diagnosis (n = 24) and those with a single diagnosis (n = 15). However, children with two or more diagnoses (n = 10) scored significantly lower in general adaptive functioning, intellectual ability, language production, and verbal comprehension compared to those with only one or no diagnosis. The results indicate that compared to children with only one diagnosis or no diagnosis, children with two or more diagnoses scored lower on several key functional domains, emphasizing the need to prioritize children with multiple diagnoses or confirmed functional impairment in clinical settings. Moreover, the findings indicate that a single diagnosis in preschool-aged children should not be a stand-alone outcome measure in sibling studies, if the goal is to identify early processes that predict meaningful differences in everyday functioning.

The pupillary light reflex (PLR), the automatic constriction of the pupil in response to increased luminance, is a candidate early intermediate phenotype associated with autism, with potential to help understand early neurodevelopmental differences because it is controlled by relatively simple neural circuitry. We conducted epigenome-wide association analyses of PLR onset latency and constriction amplitude at 9, 14, and 24 months, with 51 male infants enriched for familial autism likelihood (~ 80% with a first-degree autistic relative), using buccal DNA collected at 9 months. We identified four epigenome-wide differentially methylated probes (p < 2.4 × 10⁻⁷) significantly associated with PLR latency at 14 and 24 months, and 14- to 24-month developmental change in latency. Probes linked to PLR amplitude were identified at a discovery threshold (p < 5 × 10⁻⁵). Regional analyses revealed multiple differentially methylated regions associated with both latency and amplitude. Associated probes were enriched for neurodevelopmental processes and autism-associated genes, including NR4A2, HNRNPU, and NAV2. While the findings are most directly relevant to male infants in whom PLR variability may be associated with familial autism likelihood, they provide novel evidence that DNAm contributes to early variation in PLR. These insights into the biological underpinnings of this reflex support PLR as an early intermediate phenotype associated with autism.

In a previously published study, we found atypical visual cortical laterality patterns during global motion perception in 5-month-old infants who showed high levels of autistic symptoms in toddlerhood. Here, using data from a separate experiment within the same recording session, we examined whether these results could reflect altered visual cortical functional connectivity in theta, alpha, and gamma rhythms. We assessed this in a sample of 5-month- old infants (n = 59; 39 elevated familial likelihood of autism) by means of electroencephalography (EEG) when they were watching videos showing social and non-social scenes. Gamma connectivity between midline and far-lateral visual cortex when viewing social scenes was linked to both later autism symptoms and global motion visual cortical laterality we reported in the previous study. This may indicate a shared integrative mechanism underlying social perception and global motion processing. Further, we found that higher midline-to-lateral theta connectivity in the visual cortex when perceiving non-social scenes in infancy was strongly associated with having more autistic symptoms at follow up, but uncorrelated with concurrent motion perception. Our study points to atypical functional connectivity in the visual cortex as a potential early marker of autistic symptoms and highlights a probable link between motion processing and social perception.

Missing data are common in social and clinical sciences and understanding the causes and patterns of missing data is important for selecting analysis approach and for the interpretation of the remaining data. Yet, knowledge about the factors influencing data loss is limited. Here, we assessed the contribution of genes and environments to data missingness across three experiments of infant brain and behavioural development. The sample consisted of 594 infant twins (330 monozygotic, 152 female, 178 male infants; 264 dizygotic, 132 female, 132 male infants) who were assessed with electroencephalography (EEG), pupillometry, and gaze tracking technologies at 5 months of age. Substantial familial factors (additive genetics and/or shared environment) for data missingness were found across all experiments. The amount of missing data showed only a low correlation across the experiments, suggesting a high degree of specificity in the factors contributing to missingness. The results underscore the need to adopt and improve procedural and analytical strategies that minimise data loss and its negative impacts on study conclusions.

Background: Sleep and behavioral regulation are both vital for early healthy development. Yet, little is known about the relative contribution of genetic and environmental factors to early sleep and regulatory behaviors, or how these etiological influences may change during the first months of life.

Methods: Genetic and environmental influences on sleep, settle, and crying behaviors at 2 and 5 months were examined in 998 twins, using a classical twin design. In addition, polygenic scores were derived for a range of sleep behaviors, as well as psychiatric and neurodevelopmental conditions.

Results: Genetic influences (A) explained a large part of the variation in duration of crying at both 2 and 5 months (A = 0.29–0.70) and in settle ability at 5 months (A = 0.51–0.67). Shared environment (C) primarily influenced number of wakeups per night at both ages (C = 0.61–0.90) and settle ability at 2 months (C = 0.36–0.65). Longitudinal analyses suggested modest shared genetic influence on settle ability in the daytime across the ages (24%), and non-significant shared genetic estimates for ability to settle in the evening and at nighttime. There was moderate shared influence of shared environmental factors on number of wakeups per night (56%) and modest but significant shared genetic influence on crying duration in the evening and nighttime (17%–33%). Unique environmental effects were mostly specific to each age. Finally, autism polygenic score associated with longer crying duration in the evening at 2 months (β = 0.16, p = .002).

Conclusions: Etiological influences tended to change from 2 to 5 months, reflecting a highly plastic period in infant brain development and in child-environment interactions.

Sleep, settle, and crying behaviors represent basic regulatory functions in early infancy, yet little is known about the factors that influence these behaviors and their relationship to later development in the general population. In this study, we assessed a sample of 362 infants, measuring parent-rated number of wakeups per night, time to settle, and crying duration at 2 months of corrected age (range 27–99 days), along with various background variables. We also measured several aspects of the infants? later development at 14 and 24 months. Age (corrected) at the first assessment showed a significant association with number of wakeups per night (β = -0.212, p < 0.001) and crying duration (β = –0.154, p = 0.012). Family income was a significant predictor of crying duration (β = –0.128, p = 0.018) and time to settle (β = –0.147, p = 0.011). Sleep, settle, and crying behaviors at 2 months were not significantly associated with parent-rated language comprehension or socio-communicative abilities at 14 months, nor with vocabulary, autistic traits, or hyperactivity at 24 months. While some sleep and settle behaviors in the first few months can be challenging for caregivers, our findings suggest that they are not indicators of atypical development in early childhood in the general population.

Summary

• In a sample of more than 350 infants, we found that higher family income was associated with shorter time until settled and shorter crying duration at 2 months of age.
• Sleep, settle, and crying behaviors at 2 months did not show statistically significant associations with language development, hyperactivity, or autistic traits in toddlerhood.

1H-Magnetic resonance spectroscopy (1H-MRS) is a noninvasive technique for quantifying brain metabolites, including glutamate, glutathione (GSH), and γ-aminobutyric acid (GABA), which are essential for brain function and implicated in various neurodevelopmental conditions. As such, 1H-MRS methods that enable reliable and accurate measurement of these metabolites are of considerable clinical value. Hadamard Encoding and Reconstruction of MEGA-Edited Spectroscopy (HERMES; echo time [TE] = 80 ms) is a spectral editing technique that allows for the simultaneous quantification of GABA and GSH, using subtraction approaches to resolve these metabolites in a difference spectrum. Additionally, glutamate plus glutamine resonances (Glx) can be resolved either from the HERMES GABA-edited difference spectrum (GABA-DIFF) or from the sum of all HERMES transients (SUM spectrum). However, the reliability of 80-ms HERMES for quantification of Glx has not been systematically assessed. Here, we evaluate the agreement between Glx obtained from HERMES GABA-DIFF and SUM spectra with Glx derived from short-TE PRESS (TE = 35 ms), which is conventionally used for Glx estimation and has demonstrated reproducibility. Data were acquired from 139 participants across two brain regions (ACC and Thalamus voxels), three scanners, two diagnostic groups (autism and neurotypical development) and two age groups (adolescent/adult and preschooler). Comparisons were made using both creatine-scaled and tissue-corrected Glx estimates. Our findings demonstrate significant systematic and proportional bias between Glx estimates from HERMES (SUM and GABA-DIFF) and short-TE PRESS, consistent across scanners, voxels, age groups and diagnostic categories. These findings indicate that Glx estimates derived from HERMES are not directly comparable to those from short-TE PRESS, and this discrepancy is consistent across a multisite study setting. This underscores the importance of sequence selection and careful methodological consideration when integrating and interpreting data from 1H-MRS across different acquisition protocols.

It has been suggested that bilinguals take greater advantage of visual speech cues than monolinguals. Therefore, in a sample of 474 (47.3% females) monolingual and 101 (48.5% females) bilingual infants at 5 months of age, we examined the tendency to look at the eyes versus the mouth of dynamic faces, as well as the latency and ratio of looking at a static face interspersed with non-social objects. No significant differences were found for these measures, suggesting that monolingual and bilingual infants orient to and scan faces in a similar way. Although no association was found between the tendency to look at eyes versus mouth at 5 months and vocabulary at 24 and 36 months, a higher tendency to look at the eyes was related to a larger receptive vocabulary at 14 months, but only in the monolingual group (β = 0.15, 95% CI: 0.04; 0.27, p = 0.011). However, the difference in beta values of this association between mono- and bilinguals was not statistically significant. In conclusion, we did not find support for the hypothesis that bilingual infants rely on visual speech cues from the mouth more than monolinguals do, and there was no association between the tendency to look at eyes versus mouth and later language development in the bilingual group.

Summary

• It has been suggested that bilinguals take greater advantage of visual speech cues than monolinguals.
• Here, no differences between bilingual and monolingual 5-month-olds were found regarding any measures of face scanning.
• The findings suggest similar visual attention patterns in mono- and bilingual infants, with no impact on bilingual language development.

Twin studies are important for research on genetic and environmental influences on child development, but it is imperative to test whether findings can be generalised from twins to singletons. Since the first months of life are defined by the emergence of important sleep behaviours, we compared 451 (54.8% females) twins and 77 singletons (48.1% females) on a range of sleep, settle and crying behaviours at 5 months of age. No significant differences were found regarding duration of crying or time until settled. However, singletons were reported to wake up more frequently during nighttime than twins (F(1, 509) = 35.10, p < 0.001, η_p² = 0.065), suggesting that, when reported in twin studies, this measure might be slightly underestimated at a mean level in relation to singletons. In conclusion, despite the unique challenges and additional caregiver load of infant twins, there seem to be few differences between twins and singletons regarding parent-reported settle and crying behaviours in early infancy.