Brain enlargement has been observed in children with autism spectrum disorder (ASD), but the timing of this phenomenon, and the relationship between ASD and the appearance of behavioural symptoms, ...are unknown. Retrospective head circumference and longitudinal brain volume studies of two-year olds followed up at four years of age have provided evidence that increased brain volume may emerge early in development. Studies of infants at high familial risk of autism can provide insight into the early development of autism and have shown that characteristic social deficits in ASD emerge during the latter part of the first and in the second year of life. These observations suggest that prospective brain-imaging studies of infants at high familial risk of ASD might identify early postnatal changes in brain volume that occur before an ASD diagnosis. In this prospective neuroimaging study of 106 infants at high familial risk of ASD and 42 low-risk infants, we show that hyperexpansion of the cortical surface area between 6 and 12 months of age precedes brain volume overgrowth observed between 12 and 24 months in 15 high-risk infants who were diagnosed with autism at 24 months. Brain volume overgrowth was linked to the emergence and severity of autistic social deficits. A deep-learning algorithm that primarily uses surface area information from magnetic resonance imaging of the brain of 6-12-month-old individuals predicted the diagnosis of autism in individual high-risk children at 24 months (with a positive predictive value of 81% and a sensitivity of 88%). These findings demonstrate that early brain changes occur during the period in which autistic behaviours are first emerging.
Recent research has begun to establish the very important role of prepubertal, pubertal, and peripubertal neurodevelopment and the developmental expression of adolescent-onset psychiatric disorders. ...There are definite changes in the rates and expression of psychiatric disorders during this time period of marked hormonal changes, with increases in rates of both major depression and anxiety disorders, particularly in females, and a sharp increase in risk-taking behavior in both males and females. Recent reports underscore the critical roles that neurodevelopmental changes contribute to the development of psychiatric disorders. Typical pubertal developmental changes, such as generalized growth spurts, breast and genital bodily maturation, and the onset of menstruation are strongly related to developmental changes in hormonal expression. Until recently, however, many behavioral and psychiatric investigations (including neuroimaging investigations) did not measure hormonal levels. Such investigations, by a small number of investigators, have been completed over the past 5 to 10 years. These studies make it clear that we need to substantially increase our understanding of the endocrine-related neurodevelopmental processes in periadolescence and adolescence as they relate to the expression of many psychiatric. Barendse et al.,
published in this issue, reports some interesting findings that advance our understanding of adrenarcheal brain development, dehydroepiandrosterone (DHEA), and its relationship to anxiety symptoms.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social deficits and repetitive behaviors that typically emerge by 24 months of age. To develop effective early ...interventions that can potentially ameliorate the defining deficits of ASD and improve long-term outcomes, early detection is essential. Using prospective neuroimaging of 59 6-month-old infants with a high familial risk for ASD, we show that functional connectivity magnetic resonance imaging correctly identified which individual children would receive a research clinical best-estimate diagnosis of ASD at 24 months of age. Functional brain connections were defined in 6-month-old infants that correlated with 24-month scores on measures of social behavior, language, motor development, and repetitive behavior, which are all features common to the diagnosis of ASD. A fully cross-validated machine learning algorithm applied at age 6 months had a positive predictive value of 100% 95% confidence interval (CI), 62.9 to 100, correctly predicting 9 of 11 infants who received a diagnosis of ASD at 24 months (sensitivity, 81.8%; 95% CI, 47.8 to 96.8). All 48 6-month-old infants who were not diagnosed with ASD were correctly classified specificity, 100% (95% CI, 90.8 to 100); negative predictive value, 96.0% (95% CI, 85.1 to 99.3). These findings have clinical implications for early risk assessment and the feasibility of developing early preventative interventions for ASD.
Background
Atypical sensory responsivity and sensory interests are now included in the DSM 5 diagnostic criteria for autism spectrum disorder (ASD) under the broad domain of restricted and repetitive ...behavior (RRB). However, relatively little is known about the emergence of sensory‐related features and their relation to conventionally defined RRB in the first years of life.
Methods
Prospective, longitudinal parent‐report data using the Sensory Experiences Questionnaire (SEQ) were collected for 331 high‐risk toddlers (74 of whom met diagnostic criteria for ASD at age 2) and 135 low‐risk controls. Longitudinal profiles for SEQ scores were compared between groups across ages 12–24 months. Associations between SEQ measures and measures of RRB subtypes (based on the Repetitive Behavior Scale, Revised) were also examined.
Results
Longitudinal profiles for all SEQ scores significantly differed between groups. SEQ scores were elevated for the ASD group from age 12 months, with differences becoming more pronounced across the 12–24 month interval. At both 12 and 24 months, most measures derived from the SEQ were significantly associated with all subtypes of RRB.
Conclusions
These findings suggest that differences in sensory responsivity may be evident in high‐risk infants later diagnosed with ASD in early toddlerhood, and that the magnitude of these differences increases over the second year of life. The high degree of association between SEQ scores and RRB supports the conceptual alignment of these features but also raises questions as to explanatory mechanisms.
Abstract Background We previously reported that infants who developed autism spectrum disorder (ASD) had increased cerebrospinal fluid (CSF) in the subarachnoid space (i.e., extra-axial CSF) from 6 ...to 24 months of age. We attempted to confirm and extend this finding in a larger independent sample. Methods A longitudinal magnetic resonance imaging study of infants at risk for ASD was carried out on 343 infants, who underwent neuroimaging at 6, 12, and 24 months. Of these infants, 221 were at high risk for ASD because of an older sibling with ASD, and 122 were at low risk with no family history of ASD. A total of 47 infants were diagnosed with ASD at 24 months and were compared with 174 high-risk and 122 low-risk infants without ASD. Results Infants who developed ASD had significantly greater extra-axial CSF volume at 6 months compared with both comparison groups without ASD (18% greater than high-risk infants without ASD; Cohen’s d = 0.54). Extra-axial CSF volume remained elevated through 24 months ( d = 0.46). Infants with more severe autism symptoms had an even greater volume of extra-axial CSF from 6 to 24 months (24% greater at 6 months, d = 0.70; 15% greater at 24 months, d = 0.70). Extra-axial CSF volume at 6 months predicted which high-risk infants would be diagnosed with ASD at 24 months with an overall accuracy of 69% and corresponding 66% sensitivity and 68% specificity, which was fully cross-validated in a separate sample. Conclusions This study confirms and extends previous findings that increased extra-axial CSF is detectable at 6 months in high-risk infants who develop ASD. Future studies will address whether this anomaly is a contributing factor to the etiology of ASD or an early risk marker for ASD.
Abstract Background Autism Spectrum Disorder (ASD) is a developmental disorder defined by behavioural features that emerge during the first years of life. Research indicates that abnormalities in ...brain connectivity are associated with these behavioural features. However, inclusion of individuals past the age of onset of the defining behaviours complicates interpretation of the observed abnormalities: they may be cascade effects of earlier neuropathology and behavioural abnormalities. Our recent study of network efficiency in a cohort of 24-month-olds at high and low familial risk for ASD reduced this confound; we reported reduced network efficiencies in toddlers classified as ASD. The current study maps the emergence of these inefficiencies in the first year of life. Methods The study utilizes data from 260 infants at 6 and 12 months of age, including 116 infants with longitudinal data. As in our earlier study, we use diffusion data to obtain measures of the length and strength of connections between brain regions in order to compute network efficiency. We assess group differences in efficiency within linear mixed-effects models determined by the Akaike information criterion. Results Inefficiencies in high-risk infants later classified as ASD were detected from 6 months onward in regions involved in low-level sensory processing. Additionally, within the high-risk infants, these inefficiencies predicted 24-month symptom severity. Conclusion These results suggest that infants with ASD, even before 6 months of age, have deficits in connectivity related to low-level processing, which contribute to a developmental cascade affecting brain organization, and eventually higher-level cognitive processes and social behaviour.
Early maternal support has been shown to promote specific gene expression, neurogenesis, adaptive stress responses, and larger hippocampal volumes in developing animals. In humans, a relationship ...between psychosocial factors in early childhood and later amygdala volumes based on prospective data has been demonstrated, providing a key link between early experience and brain development. Although much retrospective data suggests a link between early psychosocial factors and hippocampal volumes in humans, to date there has been no prospective data to inform this potentially important public health issue. In a longitudinal study of depressed and healthy preschool children who underwent neuroimaging at school age, we investigated whether early maternal support predicted later hippocampal volumes. Maternal support observed in early childhood was strongly predictive of hippocampal volume measured at school age. The positive effect of maternal support on hippocampal volumes was greater in nondepressed children. These findings provide prospective evidence in humans of the positive effect of early supportive parenting on healthy hippocampal development, a brain region key to memory and stress modulation.
Previous studies have examined the relationships between structural brain characteristics and early life stress in adults. However, there is limited evidence for functional brain variation associated ...with early life stress in children. We hypothesized that early life stress and trauma would be associated with increased functional brain activation response to negative emotional faces in children with and without a history of depression.
Psychiatric diagnosis and life events in children (starting at age 3-5 years) were assessed in a longitudinal study. A follow-up magnetic resonance imaging (MRI) study acquired data (N = 115 at ages 7-12, 51% girls) on functional brain response to fearful, sad, and happy faces relative to neutral faces. We used a region-of-interest mask within cortico-limbic areas and conducted regression analyses and repeated-measures analysis of covariance.
Greater activation responses to fearful, sad, and happy faces in the amygdala and its neighboring regions were found in children with greater life stress. Moreover, an association between life stress and left hippocampal and globus pallidus activity depended on children's diagnostic status. Finally, all children with greater life trauma showed greater bilateral amygdala and cingulate activity specific to sad faces but not the other emotional faces, although right amygdala activity was moderated by psychiatric status.
These findings suggest that limbic hyperactivity may be a biomarker of early life stress and trauma in children and may have implications in the risk trajectory for depression and other stress-related disorders. However, this pattern varied based on emotion type and history of psychopathology.
Specific differences in visual orienting, critical in social-cognitive development, are associated with differences in white matter microstructure of the splenium.
ObjectiveThe authors sought to ...determine whether specific patterns of oculomotor functioning and visual orienting characterize 7-month-old infants who later meet criteria for an autism spectrum disorder (ASD) and to identify the neural correlates of these behaviors.MethodData were collected from 97 infants, of whom 16 were high-familial-risk infants later classified as having an ASD, 40 were high-familial-risk infants who did not later meet ASD criteria (high-risk negative), and 41 were low-risk infants. All infants underwent an eye-tracking task at a mean age of 7 months and a clinical assessment at a mean age of 25 months. Diffusion-weighted imaging data were acquired for 84 of the infants at 7 months. Primary outcome measures included average saccadic reaction time in a visually guided saccade procedure and radial diffusivity (an index of white matter organization) in fiber tracts that included corticospinal pathways and the splenium and genu of the corpus callosum.ResultsVisual orienting latencies were longer in 7-month-old infants who expressed ASD symptoms at 25 months compared with both high-risk negative infants and low-risk infants. Visual orienting latencies were uniquely associated with the microstructural organization of the splenium of the corpus callosum in low-risk infants, but this association was not apparent in infants later classified as having an ASD.ConclusionsFlexibly and efficiently orienting to salient information in the environment is critical for subsequent cognitive and social-cognitive development. Atypical visual orienting may represent an early prodromal feature of an ASD, and abnormal functional specialization of posterior cortical circuits directly informs a novel model of ASD pathogenesis.
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