Annual Research Review: Anterior Modifiers in the Emergence of Neurodevelopmental Disorders (AMEND)-a systems neuroscience approach to common developmental disorders

Twenty-four-month effortful control predicts emerging autism characteristics

Longitudinal research can assess how diverging development of multiple cognitive skills during infancy, as well as familial background, are related to the emergence of neurodevelopmental conditions. Sensorimotor and effortful control difficulties are seen in infants later diagnosed with autism; this study explored the relationships between these skills and autism characteristics in 340 infants (240 with elevated familial autism likelihood) assessed at 4-7, 8-10, 12-15, 24, and 36 months. We tested: (1) the relationship between parent-reported effortful control (Rothbart's temperament questionnaires) and sensorimotor skills (Mullen Scales of Early Learning), using random intercept cross-lagged panel modelling; (2) whether household income and maternal education predicted stable individual differences in cognition; (3) sensorimotor and effortful control skills as individual and interactive predictors of parent-reported autism characteristics (Social Responsiveness Scale) at 3 years, using multiple regression; and (4) moderation of interactions by familial likelihood. Sensorimotor skills were longitudinally associated with effortful control at the subsequent measurement point from 12-15 months. Socioeconomic status indicators did not predict stable between-infant differences in sensorimotor or effortful control skills. Effortful control skills were longitudinally related to 3-year autism characteristics from the first year of life, with evidence for an interaction with sensorimotor skills at 24 months. Effects of effortful control increased with age and were particularly important for infants with family histories of autism. Results are discussed in relation to different theoretical frameworks: Developmental Cascades and Anterior Modifiers in the Emergence of Neurodevelopmental Disorders. We suggest a role for 24-month effortful control in explaining the emergent autism phenotype. RESEARCH HIGHLIGHTS: Sensorimotor skills longitudinally predicted effortful control from 12-15 months onward but effortful control did not longitudinally predict sensorimotor skills during infancy. Measures of effortful control skills taken before the age of 1 predicted continuous variation in autism characteristics at 36 months, with associations increasing in strength with age. Effortful control (measured at 12-15 and 24 months) was a stronger predictor of 36-month autism characteristics in infants with elevated familial likelihood for autism. The relationship between 24-month sensorimotor skills and 36-month autism characteristics was stronger in infants with weaker effortful control skills.

Genetic and environmental contributions to individual differences in visual attention and oculomotor control in early infancy

Infants differ in their level of eye movement control, which at the extreme could be linked to autism. We assessed eye movements in 450 twins (225 pairs, 57% monozygotic, 46% female, aged 5-6 months) using the gap-overlap eye-tracking task. Shorter latency in the gap condition was associated with having more parent-rated autistic traits at 2 years. Latency across the task's three conditions was primarily explained by one highly heritable latent factor likely representing individual differences in basic oculomotor efficiency and/or in visual information processing. Additionally, disengagement of attention was linked to unique genetic factors, suggesting that genetic factors involved in visual attention are different from those involved in basic visual information processing and oculomotor efficiency.

Developmental trajectories in infants and pre-school children with Neurofibromatosis 1

BACKGROUND

Children with Neurofibromatosis 1 (NF1) show cognitive, behavioural and social differences compared to their peers. However, the age and sequence at which these differences begin to emerge is not fully understood. This prospective cohort study examines the cognitive, behavioural, ADHD trait and autism symptom development in infant and pre-school children with NF1 compared with typically developing (TD) children without a family history of neurodevelopmental conditions.

METHODS

Data from standardised tests was gathered at 5, 10, 14, 24 and 36 months of age (NF1 n = 35, TD n = 29). Developmental trajectories of cognitive (Mullen Scales of Early Learning, MSEL) and adaptive behavioural (Vineland Adaptive Behavior Scales, VABS) development from 5 to 36 months were analysed using linear mixed modelling. Measures of ADHD (Child Behavior Checklist) and autism traits (ADOS-2, BOSA-MV and ADI-R) were assessed at 24 and 36 months.

RESULTS

The developmental trajectory of cognitive skills (all domains of the MSEL) and behavioural skills (four domains of the VABS) differed significantly between NF1 and TD groups. Post-hoc tests demonstrated that the NF1 participants scored significantly lower than TD participants at 24 months on all MSEL and VABS domains. The NF1 cohort demonstrated higher mean autism and ADHD traits at 24 months and 14% of the NF1 cohort met a research diagnostic classification for autism at 36 months.

LIMITATIONS

The study has a relatively small sample size due to variable retention and rolling recruitment. Due to limitations imposed by the COVID-19 pandemic, we utilised the Brief Observation of Symptoms of Autism for Minimally Verbal children (BOSA-MV) for some participants, which was administered online and may not gather as accurate a picture of traits as ADOS-2. The BOSA-MV was utilised for 41% of participants with NF1 at 36 months compared to 11% at 24 months. This may explain the reduction in the percentage of children with NF1 that met autism criteria at 36 months.

CONCLUSIONS

By 24 months of age, the NF1 cohort show lower cognitive skills and adaptive behaviour and higher levels of autism and ADHD traits as compared to TD children. This has implications for developmental monitoring and referral for early interventions.

TRIAL REGISTRATION

Not applicable.

Parent-Child Interactions May Help to Explain Relations Between Parent Characteristics and Clinically Observed Child Autistic Behaviours

The importance of supporting parent-child interactions has been noted in the context of prodromal autism, but little consideration has been given to the possible contributing role of parental characteristics, such as psychological distress. This cross-sectional study tested models in which parent-child interaction variables mediated relations between parent characteristics and child autistic behaviour in a sample of families whose infant demonstrated early signs of autism (N = 103). The findings suggest that associations between parent characteristics (psychological distress; aloofness) and child autistic behaviours may be mediated by the child's inattentiveness or negative affect during interactions. These findings have important implications in developing and implementing interventions in infancy which target the synchrony of parent-child interaction with the goal to support children's social communication development.

Editorial Perspective: The paradox of precision health in early development - building large samples to yield individual-level measures

Precision health refers to the use of individualised biomarkers or predictive models to provide more tailored information about an individual's likely prognosis. For child psychiatry and psychology, we argue that this approach requires a focus on neurocognitive measures collected in early life and at large scale. However, the large sample sizes necessary to uncover individual-level predictors are currently rare in studies of neurodevelopmental conditions in early childhood. We recommend two strategies going forward: first, including neurocognitive measures in new national cohort studies, and second, synergising measures and data across currently funded longitudinal studies.

Sex differences in social brain neural responses in autism: temporal profiles of configural face-processing within data-driven time windows

Face-processing timing differences may underlie visual social attention differences between autistic and non-autistic people, and males and females. This study investigates the timing of the effects of neurotype and sex on face-processing, and their dependence on age. We analysed EEG data during upright and inverted photographs of faces from 492 participants from the Longitudinal European Autism Project (141 neurotypical males, 76 neurotypical females, 202 autistic males, 73 autistic females; age 6-30 years). We detected timings of sex/diagnosis effects on event-related potential amplitudes at the posterior-temporal channel P8 with Bootstrapped Cluster-based Permutation Analysis and conducted Growth Curve Analysis (GCA) to investigate the timecourse and dependence on age of neural signals. The periods of influence of neurotype and sex overlapped but differed in onset (respectively, 260 and 310 ms post-stimulus), with sex effects lasting longer. GCA revealed a smaller and later amplitude peak in autistic female children compared to non-autistic female children; this difference decreased in adolescence and was not significant in adulthood. No age-dependent neurotype difference was significant in males. These findings indicate that sex and neurotype influence longer latency face processing and implicates cognitive rather than perceptual processing. Sex may have more overarching effects than neurotype on configural face processing.

Evaluating early EEG correlates of restricted and repetitive behaviors for toddlers with or without autism

Background

Restricted and repetitive behaviors (RRB) are among the primary characteristics of autism spectrum disorder (ASD). Despite the potential impact on later developmental outcomes, our understanding of the neural underpinnings of RRBs is limited. Alterations in EEG alpha activity have been observed in ASD and implicated in RRBs, however, developmental changes within the alpha band requires careful methodological considerations when studying its role in brain-behavior relationships during infancy and early childhood. Novel approaches now enable the parameterization of the power spectrum into periodic and aperiodic components. This study aimed to characterize the neural correlates of RRBs in infancy by (1) comparing infant resting-state measures (periodic alpha and aperiodic activity) between infants who develop ASD, elevated likelihood infants without ASD, and low likelihood infants without ASD, and (2) evaluate whether these infant EEG measures are associated with frequency of RRBs measured at 24 months.

Methods

Baseline non-task related EEG data were collected from 12-to-14-month-old infants with and without elevated likelihood of autism (N=160), and periodic alpha activity (periodic alpha power, individual peak alpha frequency and amplitude), and aperiodic activity measures (aperiodic exponent) were calculated. Parent-reported RRBs were obtained at 24 months using the Repetitive Behavior Scale-Revised questionnaire. Group differences in EEG measures were evaluated using ANCOVA, and multiple linear regressions were conducted to assess relationships between EEG and RRB measures.

Results

No group-level differences in infant EEG measures were observed. Marginal effects analysis of linear regressions revealed significant associations within the ASD group, such that higher periodic alpha power, lower peak alpha frequency, and lower aperiodic exponent, were associated with elevated RRBs at 24 months. No significant associations were observed for non-ASD outcome groups.

Limitations

The sample size for ASD (N=19) was modest for examining brain-behavior relations. Larger sample sizes are needed to increase statistical power.

Conclusion

For infants with later ASD diagnoses, measures of alpha and aperiodic activity measured at 1-year of age were associated with later manifestation of RRBs at 2-years. Longitudinal studies are needed to elucidate whether the early trajectory of these EEG measures and their dynamic relations in development influence manifestations of RRBs in ASD.

Three year outcomes in infants with a family history of autism and/or attention deficit hyperactivity disorder

Background

Most research on early outcomes in infants with a family history (FH) of autism has focussed on categorically defined autism, although some have language and developmental delays. Less is known about outcomes in infants with a FH of attention deficit hyperactivity disorder (ADHD).

Methods

Infants with and without a FH of autism and/or ADHD, due to a first-degree relative with either or both conditions, were recruited at 5 or 10 months. Three year outcomes were characterised using latent profile analysis (LPA) across measures of cognitive ability, adaptive functioning and autism, ADHD and anxiety traits (n = 131). We additionally ran an LPA using only autism and ADHD measures, and the broader LPA in an independent cohort (n = 139) and in both cohorts combined (n = 270).

Results

A Low Developmental Level + High Behavioural Concerns class had elevated autism, ADHD and anxiety scores, low cognitive and adaptive function, and included all but one child with autism. A Low Developmental Level + Typical Behaviour class had average cognitive ability and typical behaviour but low adaptive function. A Typical Developmental Level + Some Behavioural Concerns class had average cognitive and adaptive function but slightly elevated behaviour scores. A High Developmental Level + Typical Behaviour class had above average cognitive ability and typical behaviour. All four LPAs identified classes characterised by combinations of either, or both, Low Development Level and elevated behaviour scores, as well as a typically developing class. No classes had elevated autism or ADHD traits in isolation.

Conclusions

Some infants with a FH of autism or ADHD have atypical developmental and behavioural outcomes, but do not show strong autism or ADHD traits in isolation. The field needs to recalibrate aims and methods to embrace the broader transdiagnostic pattern of outcomes seen in these infants.

Cortical responses to social stimuli in infants at elevated likelihood of ASD and/or ADHD: A prospective cross-condition fNIRS study

Autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD) are highly prevalent neurodevelopmental conditions that often co-occur and present both common and distinct neurodevelopmental profiles. Studying the developmental pathways leading to the emergence of ASD and/or ADHD symptomatology is crucial in understanding neurodiversity and discovering the mechanisms that underpin it. This study used functional near-infrared spectroscopy (fNIRS) to investigate differences in cortical specialization to social stimuli between 4- to 6-month-old infants at typical and elevated likelihood of ASD and/or ADHD. Results showed that infants at both elevated likelihood of ASD and ADHD had reduced selectivity to vocal sounds in left middle and superior temporal gyrus. Furthermore, infants at elevated likelihood of ASD showed attenuated responses to visual social stimuli in several cortical regions compared to infants at typical likelihood. Individual brain responses to visual social stimuli were associated with later autism traits, but not ADHD traits. These outcomes support our previous observations showing atypical social brain responses in infants at elevated likelihood of ASD and align with later atypical brain responses to social stimuli observed in children and adults with ASD. These findings highlight the importance of characterizing antecedent biomarkers of atypicalities in processing socially relevant information that might contribute to both phenotypic overlap and divergence across ASD and ADHD conditions and their association with the later emergence of behavioural symptoms.

Research Reviews: Advances in methods for evaluating child and adolescent mental health interventions

BACKROUND

The evidence base for interventions for child mental health and neurodevelopment is weak and the current capacity for rigorous evaluation limited. We describe some of the challenges that make this field particularly difficult and expensive for evaluation studies.

METHODS

We describe and review the use of novel study designs and analysis methodology for their potential to improve this situation.

RESULTS

While several novel designs appeared ill-suited to our field, systematic review found others that offered potential but had yet to be widely adopted, some not at all.

CONCLUSIONS

While funding is inevitably a constraint, we argue that improvements in the evidence base of both current and new treatments will only be achieved by the adoption of a number of these new technologies and study designs, the consistent application of rigorous constructive but demanding standards, and the engagement of the public, patients, clinical and research services to build a design, recruitment, and analysis infrastructure.

In Context: A Developmental Model of Reward Processing, With Implications for Autism and Sensitive Periods

OBJECTIVE

Differences in reward processing have been associated with numerous psychiatric disorders, including autism and attention-deficit/hyperactivity disorder (ADHD). Many attempts to understand reward processing characterize differences in clinical populations after disorder onset; however, divergence may begin much earlier. In fact, the typical developmental progression of reward processing in infancy and early childhood is poorly understood. We re-conceptualize classic infant developmental constructs such as preferential looking into a Six-Component Developmental Model of Reward Processing: an infant- and young child-focused framework to guide research and assessment of reward processing across development.

METHOD

The extant developmental literature including recent textbooks, systematic reviews, and meta-analyses was reviewed to build a conceptual framework. We describe experimental paradigms to assess each developmental component of reward processing longitudinally from infancy. A timeline of each component's emergence was estimated.

RESULTS

Six components of reward processing were identified-association, discrimination, preference/valuation, effort, anticipation, and response. Selected evidence suggests emergence between birth and 6 months. Application of this model to autism led to a reinterpretation of existing disparate results, and illuminated a path to study the developmental processes underlying a popular hypothesis of autism, the motivation hypothesis. Current evidence further suggests that a sensitive period may exist for the emergence of reward processing.

CONCLUSION

The proposed framework offers a useful reconceptualization of the extant literature. Future longitudinal work using the suggested experimental paradigms with high-risk populations could elucidate the developmental trajectory of the components and timing of potential sensitive period(s) for each component.

Activity in developing prefrontal cortex is shaped by sleep and sensory experience

In developing rats, behavioral state exerts a profound modulatory influence on neural activity throughout the sensorimotor system, including primary motor cortex (M1). We hypothesized that similar state-dependent modulation occurs in prefrontal cortical areas with which M1 forms functional connections. Here, using 8- and 12-day-old rats cycling freely between sleep and wake, we record neural activity in M1, secondary motor cortex (M2), and medial prefrontal cortex (mPFC). At both ages in all three areas, neural activity increased during active sleep (AS) compared with wake. Also, regardless of behavioral state, neural activity in all three areas increased during periods when limbs were moving. The movement-related activity in M2 and mPFC, like that in M1, is driven by sensory feedback. Our results, which diverge from those of previous studies using anesthetized pups, demonstrate that AS-dependent modulation and sensory responsivity extend to prefrontal cortex. These findings expand the range of possible factors shaping the activity-dependent development of higher-order cortical areas.

Association between motor and math skills in preschool children with typical development: Systematic review

Mathematics has been the subject in which many school-age children have revealed many difficulties. Research carried out in an attempt to understand the causes of failure in this area pointed to a positive association between mathematical performance and motor performance. Given the importance of math development in future school outcomes, knowing which specific motor components are most associated with math performance can help educators define better strategies for teaching mathematics. In this sense, the present systematic review study aimed to identify the components of motor skills most positively associated with mathematical performance in children with typical development who attend preschool. The PRISMA methodology (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) was used in this study. The databases searched were ERIC, PubMED, SciELO, Scopus and Web of Science. A total of 2,909 articles were identified, of which 18 were included in this systematic review. The main results showed positive associations between fine motor skills, namely fine motor coordination and visuomotor integration, and mathematical performance. The math skill of numerical counting was the most associated with FMS. The main characteristics of the instruments used showed that the tasks of copying figures or drawings are the most used to assess visuomotor integration and the tasks of handling objects with pinch-like movements are the most used to assess fine motor coordination. Given the importance of mathematical performance in future school results, identifying early children with difficulties in fine motor skills will help educators to design better strategies for teaching mathematical skills. In this sense, the need to identify instruments to assess fine motor skills in preschool children with characteristics that facilitate their administration by the educator in the classroom context, i.e., requiring little administration time, not requiring much experience or training, the possibility of being administered to the group/class, few material resources, and the results can be easily interpreted, classified, and associated with mathematical performance.

Advancing research on early autism through an integrated risk and resilience perspective

To date, a deficit-oriented approach dominates autism spectrum disorder (ASD) research, including studies of infant siblings of children with ASD at high risk (HR) for the disabilities associated with this disorder. Despite scientific advances regarding early ASD-related risk, there remains little systematic investigation of positive development, limiting the scope of research and quite possibly a deeper understanding of pathways toward and away from ASD-related impairments. In this paper, we argue that integrating a resilience framework into early ASD research has the potential to enhance knowledge on prodromal course, phenotypic heterogeneity, and developmental processes of risk and adaptation. We delineate a developmental systems resilience framework with particular reference to HR infants. To illustrate the utility of a resilience perspective, we consider the "female protective effect" and other evidence of adaptation in the face of ASD-related risk. We suggest that a resilience framework invites focal questions about the nature, timing, levels, interactions, and mechanisms by which positive adaptation occurs in relation to risk and developmental pathways toward and away from ASD-related difficulties. We conclude with recommendations for future research, including more focus on adaptive development and multisystem processes, pathways away from disorder, and reconsideration of extant evidence within an integrated risk-and-resilience framework.

Attention along the cortical hierarchy: Development matters

We build on the existing biased competition view to argue that attention is an emergent property of neural computations within and across hierarchically embedded and structurally connected cortical pathways. Critically then, one must ask, what is attention emergent from? Within this framework, developmental changes in the quality of sensory input and feedforward-feedback information flow shape the emergence and efficiency of attention. Several gradients of developing structural and functional cortical architecture across the caudal-to-rostral axis provide the substrate for attention to emerge. Neural activity within visual areas depends on neuronal density, receptive field size, tuning properties of neurons, and the location of and competition between features and objects in the visual field. These visual cortical properties highlight the information processing bottleneck attention needs to resolve. Recurrent feedforward and feedback connections convey sensory information through a series of steps at each level of the cortical hierarchy, integrating sensory information across the entire extent of the cortical hierarchy and linking sensory processing to higher-order brain regions. Higher-order regions concurrently provide input conveying behavioral context and goals. Thus, attention reflects the output of a series of complex biased competition neural computations that occur within and across hierarchically embedded cortical regions. Cortical development proceeds along the caudal-to-rostral axis, mirroring the flow in sensory information from caudal to rostral regions, and visual processing continues to develop into childhood. Examining both typical and atypical development will offer critical mechanistic insight not otherwise available in the adult stable state. This article is categorized under: Psychology > Attention.

Infant excitation/inhibition balance interacts with executive attention to predict autistic traits in childhood

BACKGROUND

Autism is proposed to be characterised by an atypical balance of cortical excitation and inhibition (E/I). However, most studies have examined E/I alterations in older autistic individuals, meaning that findings could in part reflect homeostatic compensation. To assess the directionality of effects, it is necessary to examine alterations in E/I balance early in the lifespan before symptom emergence. Recent explanatory frameworks have argued that it is also necessary to consider how early risk features interact with later developing modifier factors to predict autism outcomes.

METHOD

We indexed E/I balance in early infancy by extracting the aperiodic exponent of the slope of the electroencephalogram (EEG) power spectrum ('1/f'). To validate our index of E/I balance, we tested for differences in the aperiodic exponent in 10-month-old infants with (n = 22) and without (n = 27) neurofibromatosis type 1 (NF1), a condition thought to be characterised by alterations to cortical inhibition. We then tested for E/I alterations in a larger heterogeneous longitudinal cohort of infants with and without a family history of neurodevelopmental conditions (n = 150) who had been followed to early childhood. We tested the relevance of alterations in E/I balance and our proposed modifier, executive attention, by assessing whether associations between 10-month aperiodic slope and 36-month neurodevelopmental traits were moderated by 24-month executive attention. Analyses adjusted for age at EEG assessment, sex and number of EEG trials.

RESULTS

Infants with NF1 were characterised by a higher aperiodic exponent, indicative of greater inhibition, supporting our infant measure of E/I. Longitudinal analyses showed a significant interaction between aperiodic slope and executive attention, such that higher aperiodic exponents predicted greater autistic traits in childhood, but only in infants who also had weaker executive functioning abilities.

LIMITATIONS

The current study relied on parent report of infant executive functioning-type abilities; future work is required to replicate effects with objective measures of cognition.

CONCLUSIONS

Results suggest alterations in E/I balance are on the developmental pathway to autism outcomes, and that higher executive functioning abilities may buffer the impact of early cortical atypicalities, consistent with proposals that stronger executive functioning abilities may modify the impact of a wide range of risk factors.

Modulation of EEG theta by naturalistic social content is not altered in infants with family history of autism

Theta oscillations (spectral power and connectivity) are sensitive to the social content of an experience in typically developing infants, providing a possible marker of early social brain development. Autism is a neurodevelopmental condition affecting early social behaviour, but links to underlying social brain function remain unclear. We explored whether modulations of theta spectral power and connectivity by naturalistic social content in infancy are related to family history for autism. Fourteen-month-old infants with (family history; FH; N = 75) and without (no family history; NFH; N = 26) a first-degree relative with autism watched social and non-social videos during EEG recording. We calculated theta (4-5 Hz) spectral power and connectivity modulations (social-non-social) and associated them with outcomes at 36 months. We replicated previous findings of increased theta power and connectivity during social compared to non-social videos. Theta modulations with social content were similar between groups, for both power and connectivity. Together, these findings suggest that neural responses to naturalistic social stimuli may not be strongly altered in 14-month-old infants with family history of autism.

Unique dynamic profiles of social attention in autistic females

BACKGROUND

Social attention affords learning opportunities across development and may contribute to individual differences in developmental trajectories, such as between male and female individuals, and in neurodevelopmental conditions, such as autism.

METHODS

Using eye-tracking, we measured social attention in a large cohort of autistic (n = 123) and nonautistic females (n = 107), and autistic (n = 330) and nonautistic males (n = 204), aged 6-30 years. Using mixed Growth Curve Analysis, we modelled sex and diagnostic effects on the temporal dynamics of proportional looking time to three types of social stimuli (lean-static, naturalistic-static, and naturalistic-dynamic) and examined the link between individual differences and dimensional social and nonsocial autistic traits in autistic females and males.

RESULTS

In the lean-static stimulus, average face-looking was higher in females than in males of both autistic and nonautistic groups. Differences in the dynamic pattern of face-looking were seen in autistic vs. nonautistic females, but not males, with face-looking peaking later in the trial in autistic females. In the naturalistic-dynamic stimulus, average face-looking was higher in females than in males of both groups; changes in the dynamic pattern of face looking were seen in autistic vs. nonautistic males, but not in females, with a steeper peak in nonautistic males. Lower average face-looking was associated with higher observer-measured autistic characteristics in autistic females, but not in males.

CONCLUSIONS

Overall, we found stronger social attention in females to a similar degree in both autistic and nonautistic groups. Nonetheless, the dynamic profiles of social attention differed in different ways in autistic females and males compared to their nonautistic peers, and autistic traits predicted trends of average face-looking in autistic females. These findings support the role of social attention in the emergence of sex-related differences in autistic characteristics, suggesting an avenue to phenotypic stratification.

Emerging Verbal Functions in Early Infancy: Lessons from Observational and Computational Approaches on Typical Development and Neurodevelopmental Disorders

OBJECTIVES

Research on typically developing (TD) children and those with neurodevelopmental disorders and genetic syndromes was targeted. Specifically, studies on autism spectrum disorder, Down syndrome, Rett syndrome, fragile X syndrome, cerebral palsy, Angelman syndrome, tuberous sclerosis complex, Williams-Beuren syndrome, Cri-du-chat syndrome, Prader-Willi syndrome, and West syndrome were searched. The objectives are to review observational and computational studies on the emergence of (pre-)babbling vocalisations and outline findings on acoustic characteristics of early verbal functions.

METHODS

A comprehensive review of the literature was performed including observational and computational studies focusing on spontaneous infant vocalisations at the pre-babbling age of TD children, individuals with genetic or neurodevelopmental disorders.

RESULTS

While there is substantial knowledge about early vocal development in TD infants, the pre-babbling phase in infants with neurodevelopmental and genetic syndromes is scarcely scrutinised. Related approaches, paradigms, and definitions vary substantially and insights into the onset and characteristics of early verbal functions in most above-mentioned disorders are missing. Most studies focused on acoustic low-level descriptors (e.g. fundamental frequency) which bore limited clinical relevance. This calls for computational approaches to analyse features of infant typical and atypical verbal development.

CONCLUSIONS

Pre-babbling vocalisations as precursor for future speech-language functions may reveal valuable signs for identifying infants at risk for atypical development. Observational studies should be complemented by computational approaches to enable in-depth understanding of the developing speech-language functions. By disentangling features of typical and atypical early verbal development, computational approaches may support clinical screening and evaluation.

Pupillometric measures of altered stimulus-evoked locus coeruleus-norepinephrine activity explain attenuated social attention in preschoolers with autism spectrum disorder

Attenuated social attention has been described as a reduced preference for social compared to geometric motion in preschoolers with autism spectrum disorder (ASD). The locus coeruleus-norpinephrine (LC-NE) system modulates sensory reactivity and is a promising underlying mechanism. LC-NE activity is indexed by a stimulus-evoked pupillary response (SEPR) and partially by a luminance-adaptation pupillary response (LAPR), which were both shown to be aberrant in ASD. We examined whether SEPR and LAPR explain an attenuated social motion preference. We applied pupillometry via video-based eye tracking in young children (18-65 months) with ASD (n = 57) and typically developing (TD) children (n = 39) during a preferential looking paradigm of competing social and geometric motion and a changing light condition paradigm. We found an attenuated social motion preference in the ASD compared to the TD group. This was accompanied by atypical pupillometry showing a smaller SEPR to social motion, a larger SEPR to geometric motion and a reduced LAPR to a dark screen. SEPR but not LAPR explained the group difference in social motion preference. An ASD diagnosis was statistically predicted by the social motion preference, while this effect was mediated by the inclusion of SEPR to geometric and social motion. Our findings suggest a decreased sensory reactivity to social and increased reactivity to non-social motion in ASD, which may concurrently contribute to an attenuated social attention. The LC-NE system is supported as a promising underlying mechanism of altered social attention in young children with ASD, while the specificity of findings remains to be addressed.

A prospective study of associations between early fearfulness and perceptual sensitivity and later restricted and repetitive behaviours in infants with typical and elevated likelihood of autism

LAY ABSTRACT

Restricted interests and repetitive behaviours are central to the diagnosis of autism and can have profound effects on daily activities and quality of life. These challenges are also linked to other co-occurring conditions such as anxiety and sensory sensitivities. Here, we looked at whether early emerging signs of anxiety and sensory problems appear before symptoms of autism by studying infants with a family history of autism, as these infants are more likely to develop autism themselves. Studying infant siblings provides an opportunity for researchers to focus on early developmental markers of autism as these infants can be followed from birth. This study found that early infant signs of anxiety (e.g. fear/shyness) predicted later perceptual sensitivity, and those infants who scored higher on fear/shyness and sensitivity were more likely to experience more persistent repetitive behaviours, but also social and communication difficulties in toddlerhood. Early signs of anxiety and perceptual sensitivity may thus relate to both later social difficulties and repetitive behaviours. These findings support the importance of further research exploring the causal links between these domains in relation to autism, resulting in increased understanding of children who go onto develop autism in the future and guiding early interventions and supports.

Social Attention: Developmental Foundations and Relevance for Autism Spectrum Disorder

The use of the term "social attention" (SA) in the cognitive neuroscience and developmental psychopathology literature has increased exponentially in recent years, in part motivated by the aim to understand the early development of autism spectrum disorder (ASD). Unfortunately, theoretical discussions around the term have lagged behind its various uses. Here, we evaluate SA through a review of key candidate SA phenotypes emerging early in life, from newborn gaze cueing and preference for face-like configurations to later emerging skills such as joint attention. We argue that most of the considered SA phenotypes are unlikely to represent unique socioattentional processes and instead have to be understood in the broader context of bottom-up and emerging top-down (domain-general) attention. Some types of SA behaviors (e.g., initiation of joint attention) are linked to the early development of ASD, but this may reflect differences in social motivation rather than attention per se. Several SA candidates are not linked to ASD early in life, including the ones that may represent uniquely socioattentional processes (e.g., orienting to faces, predicting others' manual action goals). Although SA may be a useful superordinate category under which one can organize certain research questions, the widespread use of the term without proper definition is problematic. Characterizing gaze patterns and visual attention in social contexts in infants at elevated likelihood of ASD may facilitate early detection, but conceptual clarity regarding the underlying processes at play is needed to sharpen research questions and identify potential targets for early intervention.

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.

Larger pupil dilation to nonsocial sounds in infants with subsequent autism diagnosis

BACKGROUND

Studies of infants with an elevated likelihood of autism spectrum disorder can identify basic developmental processes that are associated with subsequently emerging clinical symptoms. Atypical responsiveness to sounds in infancy is such a potential early marker of autism. Here, we used pupillometry to quantify reactivity to social and nonsocial sounds in infants with a subsequent diagnosis. Previous research suggest that pupil dilation reflects attentional alerting, and link it to the locus coeruleus norepinephrine system.

METHODS

We measured pupil dilation responses to child-directed speech and the sound of running water; sounds infants often hear in their everyday life. The final sample consisted of 99 ten-month-old infants (52 girls), of whom 68 had an elevated likelihood of autism and 31 were typically developing low-likelihood infants. At follow-up (36 months of age), 18 children in the elevated-likelihood group were diagnosed with autism.

RESULTS

Compared to infants without diagnosis, the infants who were subsequently diagnosed with autism had larger pupil dilation when listening to nonsocial sounds, while reactivity to speech was strikingly similar between groups. In the total sample, more pupil dilation to the nonsocial sound was associated with higher levels of autistic symptoms. We also found that on a trial-by-trial basis, across all conditions and groups, more pupil dilation was associated with making fewer gaze shifts.

CONCLUSIONS

This study did not find evidence of atypical pupillary reactivity to child-directed speech early in life in autism. Instead, the results suggest that certain nonsocial sounds elicit atypically strong alerting responses in infants with a subsequent autism diagnosis. These findings may have important theoretical and clinical implications.

Rethinking Our Concepts and Assumptions About Autism

Autism is a clinical consensus diagnosis made based on behavioral symptoms of early developmental difficulties in domains of social-communication (SC) and restricted repetitive behaviors (RRB). Many readily assume that alongside being optimal for separating individuals based on SC and RRB behavioral domains, that the label should also be highly useful for explaining differential biology, outcomes, and treatment (BOT) responses. However, we also now take for granted the fact that the autism population is vastly heterogeneous at multiple scales, from genome to phenome. In the face of such multi-scale heterogeneity, here we argue that the concept of autism along with the assumptions that surround it require some rethinking. While we should retain the diagnosis for all the good it can do in real-world circumstances, we also call for the allowance of multiple other possible definitions that are better tailored to be highly useful for other translational end goals, such as explaining differential BOT responses.

Diagnosis on the way out - personality on the way in? Priorities in treatment in child and adolescent psychiatry

The scientific basis for practice in child psychiatry has developed apace. And has thrown up several quandries for an accepted paradigm for good practice anchored to the diagnostic schema developed in adult psychiatry. This paper hopes to stimulate discussion about where alternative paradigms might lead us on a path to precision medicine as applied to child psychiatry.

Capturing the complexity of autism: Applying a developmental cascades framework

Developmental change emerges from dynamic interactions among networks of neural activity, behavior systems, and experience-dependent processes. A developmental cascades framework captures the sequential, multilevel, cross-domain nature of human development and is ideal for demonstrating how interconnected systems have far-reaching effects in typical and atypical development. Neurodevelopmental disorders represent an intriguing application of this framework. Autism spectrum disorder (ASD) is complex and heterogeneous, with biological and behavioral features that cut across multiple developmental domains, including those that are motor, cognitive, sensory, and bioregulatory. Mapping developmental cascades in ASD can be transformational in elucidating how seemingly unrelated behaviors (e.g., those emerging at different points in development and occurring in multiple domains) are part of an interconnected neurodevelopmental pathway. In this article, we review evidence for specific developmental cascades implicated in ASD and suggest that theoretical and empirical advances in etiology and change mechanisms can be accelerated using a developmental cascades framework.

Eye Gaze in Autism Spectrum Disorder: A Review of Neural Evidence for the Eye Avoidance Hypothesis

Reduced eye contact early in life may play a role in the developmental pathways that culminate in a diagnosis of autism spectrum disorder. However, there are contradictory theories regarding the neural mechanisms involved. According to the amygdala theory of autism, reduced eye contact results from a hypoactive amygdala that fails to flag eyes as salient. However, the eye avoidance hypothesis proposes the opposite-that amygdala hyperactivity causes eye avoidance. This review evaluated studies that measured the relationship between eye gaze and activity in the 'social brain' when viewing facial stimuli. Of the reviewed studies, eight of eleven supported the eye avoidance hypothesis. These results suggest eye avoidance may be used to reduce amygdala-related hyperarousal among people on the autism spectrum.

INTERSTAARS: Attention training for infants with elevated likelihood of developing ADHD: A proof-of-concept randomised controlled trial

Attention-deficit/hyperactivity disorder (ADHD) is first diagnosed during middle childhood, when patterns of difficulty are often established. Pre-emptive approaches that strengthen developing cognitive systems could offer an alternative to post-diagnostic interventions. This proof-of-concept randomised controlled trial (RCT) tested whether computerised gaze-based attention training is feasible and improves attention in infants liable to develop ADHD. Forty-three 9- to 16-month-old infants with a first-degree relative with ADHD were recruited (11/2015-11/2018) at two UK sites and randomised with minimisation by site and sex to receive 9 weekly sessions of either (a) gaze-contingent attention training (intervention; n = 20); or (b) infant-friendly passive viewing of videos (control, n = 23). Sessions were delivered at home with blinded outcome assessments. The primary outcome was a composite of attention measures jointly analysed via a multivariate ANCOVA with a combined effect size (ES) from coefficients at baseline, midpoint and endpoint (Registration: ISRCTN37683928 ). Uptake and compliance was good but intention-to-treat analysis showed no significant differences between 20 intervention and 23 control infants on primary (ES -0.4, 95% CI -0.9 to 0.2; Complier-Average-Causal Effect ES -0.6, 95% CI -1.6 to 0.5) or secondary outcomes (behavioural attention). There were no adverse effects on sleep but a small increase in post-intervention session fussiness. Although feasible, there was no support for short-term effects of gaze-based attention training on attention skills in early ADHD. Longer-term outcomes remain to be assessed. The study highlights challenges and opportunities for pre-emptive intervention approaches to the management of ADHD.

Ethical dimensions of translational developmental neuroscience research in autism

BACKGROUND

Since the 1990s, increasing research has been devoted to the identification of biomarkers for autism to help attain more objective diagnosis; enable early prediction of prognosis; and guide individualized intervention options. Early studies focused on the identification of genetic variants associated with autism, but more recently, research has expanded to investigate neurodevelopmental markers. While ethicists have extensively discussed issues around advances in autism genomics, much less ethical scrutiny has focused on research on early neurodevelopment and on the interventions being developed as a result.

OBJECTIVES

We summarize the current state of the science on the identification of early markers for autism and its potential clinical applications, before providing an overview of the ethical issues arising from increasing understanding of children's neurodevelopment in very early life.

RESULTS

Advances in the understanding of brain and behavioral trajectories preceding later autism diagnosis raise ethical concerns around three themes: (a) New models for understanding autism; (b) Risks and benefits of early identification and intervention; and (c) Communication of early concerns to families. These ethical issues should be further investigated in research conducted in partnership with autistic people and their families.

CONCLUSIONS

This paper highlights the need for ethical scrutiny of early neurodevelopmental research in autism. Scrutiny requires expertise and methods from the basic sciences and bioethics, as well as constructive collaborations among autistic people, their parents, and autism researchers to anticipate early interventions that serve the community's interests and accommodate the varied experiences and preferences of people on the spectrum and their families.

Development of the pupillary light reflex from 9 to 24 months: association with common autism spectrum disorder (ASD) genetic liability and 3-year ASD diagnosis

BACKGROUND

Although autism spectrum disorder (ASD) is heritable, the mechanisms through which genes contribute to symptom emergence remain unclear. Investigating candidate intermediate phenotypes such as the pupillary light reflex (PLR) prospectively from early in development could bridge genotype and behavioural phenotype.

METHODS

Using eye tracking, we longitudinally measured the PLR at 9, 14 and 24 months in a sample of infants (N = 264) enriched for a family history of ASD; 27 infants received an ASD diagnosis at 3 years. We examined the 9- to 24-month developmental trajectories of PLR constriction latency (onset; ms) and amplitude (%) and explored their relation to categorical 3-year ASD outcome, polygenic liability for ASD and dimensional 3-year social affect (SA) and repetitive/restrictive behaviour (RRB) traits. Polygenic scores for ASD (PGS_ASD ) were calculated for 190 infants.

RESULTS

While infants showed a decrease in latency between 9 and 14 months, higher PGS_ASD was associated with a smaller decrease in latency in the first year (β = -.16, 95% CI = -0.31, -0.002); infants with later ASD showed a significantly steeper decrease in latency (a putative 'catch-up') between 14 and 24 months relative to those with other outcomes (typical: β = .54, 95% CI = 0.08, 0.99; other: β = .53, 95% CI = 0.02, 1.04). Latency development did not associate with later dimensional variation in ASD-related traits. In contrast, change in amplitude was not related to categorical ASD or genetics, but decreasing 9- to 14-month amplitude was associated with higher SA (β = .08, 95% CI = 0.01, 0.14) and RRB (β = .05, 95% CI = 0.004, 0.11) traits.

CONCLUSIONS

These findings corroborate PLR development as possible intermediate phenotypes being linked to both genetic liability and phenotypic outcomes. Future work should incorporate alternative measures (e.g. functionally informed structural and genetic measures) to test whether distinct neural mechanisms underpin PLR alterations.

Editorial: 'In our time': Has the pandemic changed the way we write and read mental health and neurodevelopmental disorder research reviews?

The past year was marked by upheaval, as countries across the globe shut down in the face of the COVID-19 pandemic. Although the topics for this year's Annual Research Review were decided long before most of had heard of the coronavirus, many readers may find themselves reading the papers in this issue through a pandemic lens. For some authors, the COVID-19 pandemic and the social unrest that characterized parts of the world where these authors live are likely to have shaped the way they ultimately framed the topics of their reviews. This issue serves as a reminder that it is critical to read science in social and historical context. Our preoccupations as psychologists and psychiatrists reflect our cultural values and societal experiences at a particular time and place.

Commentary: Meeting the challenge of multidimensionality in neurodevelopmental disorders-reflections on Johnson et al. (2021)

Neurodevelopmental disorders are widely acknowledged to be complex and multifactorial in origin, but this is rarely reflected in the approaches used to study them. We reflect on the 2021 Annual Research review and its introduction of a new conceptual framework designed to make the complexity of early neurodevelopment more empirically tractable. We evaluate the review authors' justification, explanation, and guidance for implementation of their framework in the context of their stated goals and highlight key assumptions that support its conceptual validity. Finally, we offer a genetic epidemiological perspective on potential applications, suggesting ways in which genomic data can be used to elucidate causal mechanistic processes within the AMEND framework.

Cerebral Expression of Metabotropic Glutamate Receptor Subtype 5 in Idiopathic Autism Spectrum Disorder and Fragile X Syndrome: A Pilot Study

Multiple lines of evidence suggest that dysfunction of the metabotropic glutamate receptor subtype 5 (mGluR5) plays a role in the pathogenesis of autism spectrum disorder (ASD). Yet animal and human investigations of mGluR5 expression provide conflicting findings about the nature of dysregulation of cerebral mGluR5 pathways in subtypes of ASD. The demonstration of reduced mGluR5 expression throughout the living brains of men with fragile X syndrome (FXS), the most common known single-gene cause of ASD, provides a clue to examine mGluR5 expression in ASD. We aimed to (A) compare and contrast mGluR5 expression in idiopathic autism spectrum disorder (IASD), FXS, and typical development (TD) and (B) show the value of positron emission tomography (PET) for the application of precision medicine for the diagnosis and treatment of individuals with IASD, FXS, and related conditions. Two teams of investigators independently administered 3-[18F]fluoro-5-(2-pyridinylethynyl)benzonitrile ([18F]FPEB), a novel, specific mGluR5 PET ligand to quantitatively measure the density and the distribution of mGluR5s in the brain regions, to participants of both sexes with IASD and TD and men with FXS. In contrast to participants with TD, mGluR5 expression was significantly increased in the cortical regions of participants with IASD and significantly reduced in all regions of men with FXS. These results suggest the feasibility of this protocol as a valuable tool to measure mGluR5 expression in clinical trials of individuals with IASD and FXS and related conditions.