The Brain Basis of Comorbidity in Neurodevelopmental Disorders

Mechanistic perspective on the actions of vitamin a in autism spectrum disorder etiology

Vitamin A (VA) has many functions in the body, some of which are key for the development and functioning of the nervous system, while some others might indirectly influence neural function. Both hypovitaminosis and hypervitaminosis A can lead to clinical manifestations of concern for individuals and for general global health. Scientific evidence on the link between VA and autism spectrum disorder (ASD) is growing, with some clinical studies and accumulating results obtained from basic research using cellular and animal models. Remarkably, it has been shown that VA deficiency can exacerbate autistic symptomatology. In turn, VA supplementation has been shown to be able to improve autistic symptomatology in selected groups of individuals with ASD. However, it is important to recognize that ASD is a highly heterogeneous condition. Therefore, it is important to clarify how and when VA supplementation can be of benefit for affected individuals. Here we delve into the relationship between VA and ASD, discussing clinical observations and mechanistic insights obtained from research on selected autistic syndromes and laboratory models to advance in defining how the VA signaling pathway can be exploited for treatment of ASD.

Cognitive strengths in neurodevelopmental disorders, conditions and differences: A critical review

Neurodevelopmental disorders are traditionally characterised by a range of associated cognitive impairments in, for example, sensory processing, facial recognition, visual imagery, attention, and coordination. In this critical review, we propose a major reframing, highlighting the variety of unique cognitive strengths that people with neurodevelopmental differences can exhibit. These include enhanced visual perception, strong spatial, auditory, and semantic memory, superior empathy and theory of mind, along with higher levels of divergent thinking. Whilst we acknowledge the heterogeneity of cognitive profiles in neurodevelopmental conditions, we present a more encouraging and affirmative perspective of these groups, contrasting with the predominant, deficit-based position prevalent throughout both cognitive and neuropsychological research. In addition, we provide a theoretical basis and rationale for these cognitive strengths, arguing for the critical role of hereditability, behavioural adaptation, neuronal-recycling, and we draw on psychopharmacological and social explanations. We present a table of potential strengths across conditions and invite researchers to systematically investigate these in their future work. This should help reduce the stigma around neurodiversity, instead promoting greater social inclusion and significant societal benefits.

Childhood neurodevelopmental disorders and maternal hypertensive disorder of pregnancy

AIM

To examine the association of maternal chronic hypertension and pregnancy-induced hypertension (PIH)/preeclampsia with childhood neurodevelopmental disorders (NDDs) in a large-scale population-based cohort.

METHOD

We conducted a linked Taiwan National Health Insurance Research Database cohort study of children born between 2004 and 2008 (n=877 233). Diagnoses of autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), developmental delay, intellectual disability, cerebral palsy (CP), and epilepsy/infantile spasms were identified from birth to the end of 2015. Cox proportional hazards models were fitted with adjustment for potential confounders to estimate the effect of maternal hypertensive disorder of pregnancy on childhood outcomes.

RESULTS

Compared with the offspring of unexposed mothers, offspring of mothers with chronic hypertension or PIH/preeclampsia exhibited increased risk of developing a wide spectrum of NDDs. Chronic hypertension was associated with increased risks of ADHD (hazard ratio 1.22, 95% confidence interval [CI] 1.13-1.​31), developmental delay (1.29, 1.21-1.38), intellectual disability (1.67, 1.43-1.95), CP (1.45, 1.14-1.85), and epilepsy/infantile spasms (1.31, 1.10-1.56) in the offspring, whereas PIH/preeclampsia was associated with increased risks of ASD (1.27, 1.12-1.43), ADHD (1.23, 1.17-1.29), developmental delay (1.29, 1.24-1.35), intellectual disability (1.53, 1.37-1.71), CP (1.44, 1.22-1.70), and epilepsy/infantile spasms (1.36, 1.22-1.52) in the offspring after adjustment for potential confounders. The co-occurrence of maternal diabetes, preterm deliveries, or fetal growth restriction further increased the risk.

INTERPRETATION

Chronic hypertension or PIH/preeclampsia seems to be sufficient to increase the risk of childhood NDDs. What this paper adds Children exposed to maternal hypertensive disorders have a higher cumulative incidence of neurodevelopmental disorders (NDDs) than unexposed children. Chronic hypertension or pregnancy-induced hypertension/preeclampsia seems to be sufficient to increase the risk of childhood NDDs. Co-occurrence of maternal diabetes, preterm deliveries, or fetal growth restriction further increases the risk.

What's the Link Between Theory of Mind and Other Cognitive Abilities - A Co-twin Control Design of Neurodevelopmental Disorders

Theory of mind (ToM), or the ability to attribute mental states to oneself and others, is a core element of social cognition (SC). Even though its importance for social functioning in general, and neurodevelopmental disorders (NDDs), in particular, is well established, the links between ToM and other cognitive functions are not. Especially the familial underpinnings of such links remain unclear. Using a co-twin control design, we examined N = 311 twins (mean age M = 17.19 years, 47% females) diagnosed with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), other NDDs, or typically developing individuals. We used the Reading the Mind in the Eyes Test to operationalize ToM, the Fragmented Pictures Test for central coherence (CC), the Tower Test for executive functioning (EF), and the general ability index in the Wechsler Intelligence Scales for IQ. In the linear regressions, weak CC and a lower IQ were associated with a reduced ToM ability across pairs. Female sex and higher age were robustly associated with increased ToM ability, whereas EF was not associated with ToM. In the within-pair analyses, where unmeasured familial confounders are implicitly adjusted, the associations between ToM and other cognitive functions, were attenuated and the association with CC was non-significant. The result suggests that familial factors shared by the twins, such as genetic and shared environment, influence the association between CC, IQ, and ToM. Future studies need to include a larger sample of monozygotic twins, who are genetically identical, in order to draw more firm conclusions regarding the influence of familial factors, and to differentiate between shared environmental and genetic effects on the associations between cognitive functions.

The contributions of fetal growth restriction and gestational age to developmental outcomes at 12 months of age: A cohort study

BACKGROUND

Preterm birth is a known risk factor for infant development but it is less clear whether fetal growth restriction (FGR) and early term birth between 37 and 39 weeks gestation are associated with risks for infant development.

AIMS

This study investigated risk factors for adverse developmental outcomes at 12 months of age in a population-based birth cohort.

STUDY DESIGN

Cohort study.

SUBJECTS

Participants in the Raine Study, which recruited 2900 women at 18 weeks of gestation (Gen1) and followed up infants longitudinally (Gen2). At 12 months, 1773 mothers provided developmental data for their infants.

OUTCOME MEASURE

The Ages and Stages Questionnaire (ASQ) was used to measure gross and fine motor, communication, adaptability and personal social development. Multivariate logistic regression analyses were used to estimate associations between FGR, gestational age, sex, breast feeding, parental age, socioeconomic factors and developmental delay at 12 months of age as measured with the ASQ.

RESULTS

The risk of any delay at 12 months of age, as well as gross motor, fine motor and adaptive delay, was slightly increased for infants born FGR. Preterm and early term birth and male sex were associated with poorer development at 12 months. Breast feeding was protective of developmental status.

CONCLUSIONS

Developmental assessment using the ASQ of infants with FGR was mostly comparable to those born without FGR at 12 months, although finer-grained neurobehavioural assessments may yield capacity for earlier identification of developmental risk. Our data provide weight to the argument that surveillance of early term infants could enable earlier intervention for children at risk.