Rates of family history of autism and ADHD varies with recruitment approach and socio-economic status

Family history (FH) of autism and ADHD is not often considered during the recruitment process of developmental studies, despite high recurrence rates. We looked at the rate of autism or ADHD amongst family members of young children (9 to 46 months) in three UK-based samples (N = 1055) recruited using different methods. The rate of FH-autism or FH-ADHD was 3%-9% for diagnosed cases. The rate was highest in the sample recruited through an online participant pool, which also consisted of the most socio-economically diverse families. Lower parental education and family income were associated with higher rates of FH-ADHD and lower parental education with increased FH-autism. Thus, recruitment strategies have a meaningful impact on neurodiversity and the conclusions and generalizations that can be drawn. Specifically, recruitment using crowdsourcing websites could create a sample that is more representative of the wider population, compared to those recruited through university-related volunteer databases and social media.

Infant visual preference for the mother's face and longitudinal associations with emotional reactivity in the first year of life

Past research has focused on infants' visual preference for the mother's face, however it is still unknown how these responses change over time and what factors associate with such changes. A longitudinal study (N ~ 60) was conducted to investigate the trajectories of infant visual preference for the mother's face and how these are related to the development of emotional reactivity in the first year of life. Two face stimuli (i.e., the infant's mother and a consistent stranger face) were used in a visual preference task at 2 weeks, 4, 6, and 9 months of age. At each time point, mothers were asked to complete a measure of infant temperament via standardised questionnaires. Our results show that while at 2 weeks, 4 months and 9 months of age infants looked equally at both faces, infants at 6 months looked significantly longer at their mother's face. We also observed prospective associations with emotional reactivity variables so that infants who looked longer at the mother's face at 6 months showed higher falling reactivity, i.e. a better ability to recover from distress, at 9 months. We discuss these findings in light of the roles that both infant development and the caregiver play in emerging emotion regulation capacities during the first year of life.

We need to talk about validity - A commentary on "Six solutions for more reliable infant research" from the viewpoint of an early executive functions researcher

In their methodological article, "Six solutions for more reliable infant research", Byers-Heinlein, Bergmann and Savalei (2021) present compelling arguments for why developmental researchers should report and consider measures of reliability more frequently in their work. They also provide useful guidance on solutions to this "reliability crisis". In this commentary, I highlight a further methodological aspect that I think is key to successful and robust infancy research, that of construct validity. I also discuss recent reliability data from my own research on early executive function development, analyses which were directly inspired by the target article.

Highlights

Considering measurement reliability and effect sizes is important for robust infant research and for optimising infant tasks to measure group-level effects or individual differences.Construct validity - making sure that we measure what we think we are measuring - is also important.A robust effect at the group-level may not always restrict reliability - it depends on the amount of true variation between infants.

Development of directed global inhibition, competitive inhibition and behavioural inhibition during the transition between infancy and toddlerhood

Inhibitory control (IC) is a core executive function integral to self-regulation and cognitive control, yet is itself multi-componential. Directed global inhibition entails stopping an action on demand. Competitive inhibition is engaged when an alternative response must also be produced. Related, but not an executive function, is temperamentally-driven wariness of novelty, known as behavioural inhibition. Understanding early development of these components has been hampered by a shortage of suitable measures. We combine established and novel measures to capture directed global inhibition (Toy Prohibition, Touchscreen Prohibition), competitive inhibition (A-not-B, Early Childhood Inhibitory Touchscreen Task; ECITT) and behavioural inhibition (Touchscreen Approach) in 113 10- and 16-month-olds (73 seen longitudinally). ECITT performance shows good 1-week test-retest reliability at 10-months (r = 0.30-0.60) but little stability to 16-months. Directed global inhibition performance shows developmental progression but little stability of individual differences from 10 to 16 months. Performance on measures targeting similar IC components shows greater coherence at 16-months (r = 0.23-0.59) compared with 10-months (r = 0.09-0.35). Probing of ECITT condition effects indicates toddlers are more able, compared with infants, to override immediate prepotencies; indicative of increasingly flexible control over behaviour. However, exerting IC over cumulative prepotencies appears just as challenging for toddlers as infants. Exploratory analyses show little evidence for cross-sectional or longitudinal associations between behavioural, directed global and competitive inhibition. In combination, these findings indicate that IC is not yet a stable, unidimensional construct during the transition between infancy and toddlerhood, and highlight the need for careful selection of multiple measures for those interested in capturing early variation in IC.

The neural correlates of inhibitory control in 10-month-old infants: A functional near-infrared spectroscopy study

Inhibitory control, a core executive function, emerges in infancy and develops rapidly across childhood. Methodological limitations have meant that studies investigating the neural correlates underlying inhibitory control in infancy are rare. Employing functional near-infrared spectroscopy alongside a novel touchscreen task that measures response inhibition, this study aimed to uncover the neural underpinnings of inhibitory control in 10-month-old infants (N = 135). We found that when inhibition was required, the right prefrontal and parietal cortices were more activated than when there was no inhibitory demand. This demonstrates that inhibitory control in infants as young as 10 months of age is supported by similar brain areas as in older children and adults. With this study we have lowered the age-boundary for localising the neural substrates of response inhibition to the first year of life.

Maternal depressive symptoms and early childhood temperament before and during the COVID-19 pandemic in the United Kingdom

The COVID-19 pandemic is an unexpected and major global event, with the potential to have many and varied impacts on child development. However, the implications of the pandemic for maternal depressive symptoms, early childhood temperament dimensions, and their associations, remain largely unknown. To investigate this, questionnaires were completed by mothers (N = 175) before and during the pandemic when their child was 10- and 16-months old (Study 1), and by an extended group of mothers with young children (6-48 months; 66 additional mothers) during the first and second national lockdowns in the United Kingdom in 2020 (Study 2). Results indicated that while maternal pandemic-related stress decreased over the first 6 months of the pandemic, there was an increase in mothers who reported feeling some level of pandemic-specific depression. Despite this, we did not observe an increase in the severity of global maternal depressive symptoms, or any negative impact of the pandemic on the development of temperament in infancy and early childhood.

Maternal depressive symptoms and infant temperament in the first year of life predict child behavior at 36 months of age

In a longitudinal study, mothers (N = 50) self-reported on their depressive symptoms (DS) and their child's behavior during the first year and at 36 months postpartum. Maternal DS during infancy were associated with child conduct problems (CP), suggesting a long-term association between maternal mental health and the development of child behavior. Infant temperament was also associated with child behavior so that negative affect predicted child CP, while infant surgency was associated with later hyperactivity-inattention. This study contributes to the literature by jointly assessing the role of maternal DS and infant temperament and showing that these are independent predictors of childhood behavior.

The early childhood inhibitory touchscreen task: A new measure of response inhibition in toddlerhood and across the lifespan

Research into the earliest development of inhibitory control is limited by a lack of suitable tasks. In particular, commonly used inhibitory control tasks frequently have too high language and working memory demands for children under 3 years of age. Furthermore, researchers currently tend to shift to a new set of inhibitory control tasks between infancy, toddlerhood, and early childhood, raising doubts about whether the same function is being measured. Tasks that are structurally equivalent across age could potentially help resolve this issue. In the current report, a new response inhibition task, the Early Childhood Inhibitory Touchscreen Task (ECITT), was developed. This task can be minimally modified to suit different ages, whilst remaining structurally equivalent. In the new task, participants have to overcome a tendency to respond to a frequently rewarded location on a touchscreen and instead make an alternative response. The ECITT was validated in three independent studies (with additional data, N = 166, reported in Supporting Information). In Study 1 (N = 81), cross-sectional data indicated that inhibitory performance on the task improved significantly between 24 and 30 months of age. In Study 2 (N = 38), longitudinal data indicated steady improvement in inhibitory control between 18, 21 and 24 months, with significant stability in individual performance differences between each consecutive age in terms of accuracy (but not in terms of reaction time). Finally, in Study 3 (N = 64), inhibitory performance on a faster-paced version of the same task showed a similar developmental course across the lifespan (4-84 years) to other response inhibition tasks and was significantly correlated with Stop-signal performance. The ECITT extends the assessment of response inhibition earlier than previous tasks-into early toddlerhood. Because the task is simple and structurally equivalent across age, future longitudinal studies should benefit from using the ECITT to investigate the development of inhibitory control in a consistent manner across the toddler years and beyond.

Associations between touchscreen exposure and hot and cool inhibitory control in 10-month-old infants

Touchscreen use amongst young children has proliferated in recent years, yet little is known about the association between daily touchscreen exposure and inhibitory control in the first year of life. Previous research has found a negative association between the amount of television viewing and inhibitory control in early childhood, but it is unclear whether negative associations with screen use extend to touchscreens. The current study presents an exploratory analysis of the cross-sectional associations between inhibitory control and the amount of touchscreen use amongst 10-month-olds (n = 128-156). Touchscreen exposure was assessed via parent-report. In order to include a range of "hot" and "cool" aspects of inhibitory control, these skills were assessed using lab-based response inhibition and prohibition tasks as well as parent-reported observations of infants' inhibitory control abilities and broader regulatory behaviors. A "Cognitive Executive Function (EEFQ-CEF)" score (encompassing Inhibitory Control, Flexibility, and Working Memory items) was included as a secondary broader executive function construct to examine whether effects showed specificity to inhibitory control rather than executive functions more generally. Correlation analyses indicated no association between touchscreen exposure and the four indices of IC. However, a positive association was found for the amount of touchscreen exposure and EEFQ-CEF once accounting for sociodemographic variables. The implications of these findings and future directions are discussed.

Development and validation of the Early Executive Functions Questionnaire: A carer-administered measure of Executive Functions suitable for 9- to 30-month-olds

Executive functions (EFs) enable us to control our attention and behavior in order to set and work toward goals. Strong EF skills are linked to better academic performance, and greater health, wealth, and happiness in later life. Research into EF development has been hampered by a lack of scalable measures suitable for infancy through to toddlerhood. The 31-item Early Executive Functions Questionnaire (EEFQ) complements temperament measures by targeting cognitive and regulatory capabilities. Exploratory Factor Analysis (n = 486 8- to 30-month-olds) and Confirmatory Factor Analysis (n = 317 9- to 30-month-olds) indicate Inhibitory Control, Flexibility, and Working Memory items load onto a common "Cognitive Executive Function (CEF)" factor, while Regulation items do not. The CEF factor shows strong factorial measurement invariance for sex, and partial strong factorial measurement invariance for age. CEF and Regulation scores show limited floor and ceiling effects, good internal consistency, short-term stability, and convergent validity with carer-report measures of attentional control. The EEFQ is sensitive to developmental change. Results indicate that the widely overlooked period between late infancy and early toddlerhood may be a sensitive period for EF development. The low-resource demands of the EEFQ afford the possibility to study emergent EFs at scale; opening up new opportunities in basic developmental and intervention research.

Dynamic modulation of frontal theta power predicts cognitive ability in infancy

Cognitive ability is a key factor that contributes to individual differences in life trajectories. Identifying early neural indicators of later cognitive ability may enable us to better elucidate the mechanisms that shape individual differences, eventually aiding identification of infants with an elevated likelihood of less optimal outcomes. A previous study associated a measure of neural activity (theta EEG) recorded at 12-months with non-verbal cognitive ability at ages two, three and seven in individuals with older siblings with autism (Jones et al., 2020). In a pre-registered study (https://osf.io/v5xrw/), we replicate and extend this finding in a younger, low-risk infant sample. EEG was recorded during presentation of a non-social video to a cohort of 6-month-old infants and behavioural data was collected at 6- and 9-months-old. Initial analyses replicated the finding that frontal theta power increases over the course of video viewing, extending this to 6-month-olds. Further, individual differences in the magnitude of this change significantly predicted non-verbal cognitive ability measured at 9-months, but not early executive function. Theta change at 6-months-old may therefore be an early indicator of later cognitive ability. This could have important implications for identification of, and interventions for, children at risk of poor cognitive outcomes.

Early Development of Visual Attention: Change, Stability, and Longitudinal Associations

Visual attention is a basic mechanism of information gathering and environment selection and consequently plays a fundamental role in influencing developmental trajectories. Here, we highlight evidence for predictive associations from early visual attention to emotion regulation, executive function, language and broader cognitive ability, mathematics and literacy skills, and neurodevelopmental conditions. Development of visual attention is also multifaceted and nonlinear. In daily life, core functions such as orienting, selective filtering, and processing of visual inputs are intertwined and influenced by many other cognitive components. Furthermore, the demands of an attention task vary according to the experience, motivation, and cognitive and physical constraints of participants, while the mechanisms underlying performance may change with development. Thus, markers of attention may need to be interpreted differently across development and between populations. We summarize research that has combined multiple measurements and techniques to further our understanding of visual attention development and highlight possibilities for the future.

Neural substrates of early executive function development

In the last decade, advances in neuroimaging technologies have given rise to a large number of research studies that investigate the neural underpinnings of executive function (EF). EF has long been associated with the prefrontal cortex (PFC) and involves both a unified, general element, as well as the distinct, separable elements of working memory, inhibitory control and set shifting. We will highlight the value of utilising advances in neuroimaging techniques to uncover answers to some of the most pressing questions in the field of early EF development. First, this review will explore the development and neural substrates of each element of EF. Second, the structural, anatomical and biochemical changes that occur in the PFC during infancy and throughout childhood will be examined, in order to address the importance of these changes for the development of EF. Third, the importance of connectivity between regions of the PFC and other brain areas in EF development is reviewed. Finally, throughout this review more recent developments in neuroimaging techniques will be addressed, alongside the implications for further elucidating the neural substrates of early EF development in the future.

Strong genetic influences on the stability of autistic traits in childhood

OBJECTIVE

Disorders on the autism spectrum, as well as autistic traits in the general population, have been found to be both highly stable across age and highly heritable at individual ages. However, little is known about the overlap in genetic and environmental influences on autistic traits across age and the contribution of such influences to trait stability itself. The present study investigated these questions in a general population sample of twins.

METHOD

More than 6,000 twin pairs were rated on an established scale of autistic traits by their parents at 8, 9, and 12 years of age and by their teachers at 9 and 12 years of age. Data were analyzed using structural equation modeling.

RESULTS

The results indicated that, consistently across raters, not only were autistic traits stable, and moderately to highly heritable at individual ages, but there was also a high degree of overlap in genetic influences across age. Furthermore, autistic trait stability could largely be accounted for by genetic factors, with the environment unique to each twin playing a minor role. The environment shared by twins had virtually no effect on the longitudinal stability in autistic traits.

CONCLUSIONS

Autistic traits are highly stable across middle childhood. and this stability is caused primarily by genetic factors.

Dopamine D4 receptor and serotonin transporter gene effects on the longitudinal development of infant temperament

Existing studies of the effect on infant temperament of the 48 base pair variable number of tandem repeats polymorphism in exon 3 of the dopamine D4 receptor gene, DRD4 VNTR, and the serotonin transporter-linked polymorphic region, 5-HTTLPR, have provided contradictory results, and age seems to be an important factor. The present study investigated the effect of these two polymorphisms on the stability of infant temperament between 4 and 9 months of age. Furthermore, the effect of a recently discovered single nucleotide polymorphism which modulates the 5-HTTLPR (rs25531) was investigated in relation to infant temperament. The study sample consisted of 90 infants, who were assessed by parental report at the two ages under consideration using the Revised Infant Behavior Questionnaire. It was found that infants carrying the 7-repeat allele of the DRD4 VNTR had higher levels of Negative Affect. Furthermore, there was an interaction between DRD4 VNTR and 5-HTTLPR genotype such that infants with the DRD4 VNTR 7-repeat allele and the highest expressing 5-HTTLPR genotype (L(A) L(A) ) had the highest level of Negative Affect. These effects were largely driven by scores on the Falling Reactivity scale. Genetic effects were stable across age. The results emphasize the need for developmental studies of genetic effects on temperament.

Social and attention factors during infancy and the later emergence of autism characteristics

Characteristic features of autism include atypical social perception and social-communication skills, and atypical visual attention, alongside rigid and repetitive thinking and behavior. Debate has focused on whether the later emergence of atypical social skills is a consequence of attention problems early in life, or, conversely, whether early social deficits have knock-on consequences for the later development of attention skills. We investigated this question based on evidence from infants at familial risk for a later diagnosis of autism by virtue of being younger siblings of children with a diagnosis. Around 9months, at-risk siblings differed as a group from controls, both in measures of social perception and inhibitory control. We present preliminary data from an ongoing longitudinal research program, suggesting clear associations between some of these infant measures and autism-related characteristics at 3years. We discuss the findings in terms of the emergent nature of autism as a result of complex developmental interactions among brain networks.

Frontal cortex functioning in the infant broader autism phenotype

Atypical attention has been proposed as a marker of the broader autism phenotype. In the present study we investigated this and the related process of inhibitory control at the youngest possible age through the study of infant siblings of children with an autism spectrum disorder (Sibs-ASD). Both attention and inhibition have been related to the frontal cortex of the brain. Nine- to ten-month-old Sibs-ASD and low-risk control infants completed the Freeze-Frame task, in which infants are encouraged to inhibit looks to peripherally presented distractors whilst looking at a central animation. The attractiveness of the central stimulus is varied in order to investigate the selectivity of infants' responses. In line with previous studies, it was found that a subset of Sibs-ASD infants had difficulty disengaging attention from a central stimulus in order to orient to a peripheral stimulus. The Sibs-ASD group also showed less Selective Inhibition than controls. However, Sibs-ASD infants did demonstrate Selective Inhibitory Learning. These results provide preliminary evidence for atypical frontal cortex functioning in the infant broader autism phenotype.

Polymorphisms in dopamine system genes are associated with individual differences in attention in infancy

Knowledge about the functional status of the frontal cortex in infancy is limited. This study investigated the effects of polymorphisms in four dopamine system genes on performance in a task developed to assess such functioning, the Freeze-Frame task, at 9 months of age. Polymorphisms in the catechol-O-methyltransferase (COMT) and the dopamine D4 receptor (DRD4) genes are likely to impact directly on the functioning of the frontal cortex, whereas polymorphisms in the dopamine D2 receptor (DRD2) and dopamine transporter (DAT1) genes might influence frontal cortex functioning indirectly via strong frontostriatal connections. A significant effect of the COMT valine(1)methionine (Val 158 Met) polymorphism was found. Infants with the Met/Met genotype were significantly less distractible than infants with the Val/Val genotype in Freeze-Frame trials presenting an engaging central stimulus. In addition, there was an interaction with the DAT1 3; variable number of tandem repeats polymorphism; the COMT effect was present only in infants who did not have two copies of the DAT1 10-repeat allele. These findings indicate that dopaminergic polymorphisms affect selective aspects of attention as early as infancy and further validate the Freeze-Frame task as a frontal cortex task.

Visual orienting in the early broader autism phenotype: disengagement and facilitation

BACKGROUND

Recent studies of infant siblings of children diagnosed with autism have allowed for a prospective approach to examine the emergence of symptoms and revealed behavioral differences in the broader autism phenotype within the early years. In the current study we focused on a set of functions associated with visual attention, previously reported to be atypical in autism.

METHOD

We compared performance of a group of 9-10-month-old infant siblings of children with autism to a control group with no family history of autism on the 'gap-overlap task', which measures the cost of disengaging from a central stimulus in order to fixate a peripheral one. Two measures were derived on the basis of infants' saccadic reaction times. The first is the Disengagement effect, which measures the efficiency of disengaging from a central stimulus to orient to a peripheral one. The second was a Facilitation effect, which arises when the infant is cued by a temporal gap preceding the onset of the peripheral stimulus, and would orient faster after its onset.

RESULTS AND CONCLUSION

Infant siblings of children with autism showed longer Disengagement latencies as well as less Facilitation relative to the control group. The findings are discussed in relation to how differences in visual attention may relate to characteristics observed in autism and the broader phenotype.

Neural correlates of eye gaze processing in the infant broader autism phenotype

BACKGROUND

Studies of infant siblings of children diagnosed with autism have allowed for a prospective approach to study the emergence of autism in infancy and revealed early behavioral characteristics of the broader autism phenotype. In view of previous findings of atypical eye gaze processing in children and adults with autism, the aim of this study was to examine the early autism phenotype in infant siblings of children diagnosed with autism spectrum disorder (sib-ASD), focusing on the neural correlates of direct compared with averted gaze.

METHODS

A group of 19 sib-ASD was compared with 17 control infants with no family history of ASD (mean age=10 months) on their response to direct versus averted gaze in static stimuli.

RESULTS

Relative to the control group, the sib-ASD group showed prolonged latency of the occipital P400 event-related potentials component in response to direct gaze, but they did not differ in earlier components. Similarly, time-frequency analysis of high-frequency oscillatory activity in the gamma band showed group differences in response to direct gaze, where induced gamma activity was late and less persistent over the right temporal region in the sib-ASD group.

CONCLUSION

This study suggests that a broader autism phenotype, which includes an atypical response to direct gaze, is manifest early in infancy.