Developmental cortical thinning in fetal alcohol spectrum disorders

Brain structural differences in children with fetal alcohol spectrum disorder and its subtypes

Introduction

The teratogenic effects of prenatal alcohol exposure (PAE) have been examined in animal models and humans. The current study extends the prior literature by quantifying differences in brain structure for individuals with a fetal alcohol spectrum disorder (FASD) compared to typically developing controls, as well as examining FASD subtypes. We hypothesized the FASD group would reveal smaller brain volume, reduced cortical thickness, and reduced surface area compared to controls, with the partial fetal alcohol syndrome (pFAS)/fetal alcohol syndrome (FAS) subtypes showing the largest effects and the PAE/alcohol-related neurodevelopmental disorder (ARND) subtype revealing intermediate effects.

Methods

The sample consisted of 123 children and adolescents recruited from a single site including children with a diagnosis of FASD/PAE (26 males, 29 females) and controls (34 males, 34 females). Structural T1-weighted MRI scans were obtained on a 3T Trio TIM scanner and FreeSurfer v7.2 was used to quantify brain volume, cortical thickness, and surface area. Analyses examined effects by subgroup: pFAS/FAS (N = 32, Mage = 10.7 years, SEage = 0.79), PAE/ARND (N = 23, Mage = 10.8, SEage = 0.94), and controls (N = 68, Mage = 11.1, SEage = 0.54).

Results

Total brain volume in children with an FASD was smaller relative to controls, but subtype analysis revealed only the pFAS/FAS group differed significantly from controls. Regional analyses similarly revealed reduced brain volume in frontal and temporal regions for children with pFAS/FAS, yet children diagnosed with PAE/ARND generally had similar volumes as controls. Notable differences to this pattern occurred in the cerebellum, caudate, and pallidum where children with pFAS/FAS and PAE/ARND revealed lower volume relative to controls. In the subset of participants who had neuropsychological testing, correlations between volume and IQ scores were observed. Goodness-of-Fit analysis by age revealed differences in developmental patterns (linear vs. quadratic) between groups in some cases.

Discussion

This study confirmed prior results indicating decreased brain volume in children with an FASD and extended the results by demonstrating differential effects by structure for FASD subtypes. It provides further evidence for a complex role of PAE in structural brain development that is likely related to the cognitive and behavioral effects experienced by children with an FASD.

Delayed cortical thinning in children and adolescents with prenatal alcohol exposure

BACKGROUND

Prenatal alcohol exposure (PAE) is associated with abnormalities in cortical structure and maturation, including cortical thickness (CT), cortical volume, and surface area. This study provides a longitudinal context for the developmental trajectory and timing of abnormal cortical maturation in PAE.

METHODS

We studied 35 children with PAE and 30 nonexposed typically developing children (Comparisons), aged 8-17 at enrollment, who were recruited from the University of Minnesota FASD Program. Participants were matched on age and sex. They underwent a formal evaluation of growth and dysmorphic facial features associated with PAE and completed cognitive testing. MRI data were collected on a Siemens Prisma 3T scanner. Two sessions, each including MRI scans and cognitive testing, were spaced approximately 15 months apart on average. Change in CT and performance on tests of executive function (EF) were examined.

RESULTS

Significant age-by-group (PAE vs. Comparison) linear interaction effects in CT were observed in the parietal, temporal, occipital, and insular cortices suggesting altered developmental trajectories in the PAE vs. Comparison groups. Results suggest a pattern of delayed cortical thinning in PAE, with the Comparison group showing more rapid thinning at younger ages and those with PAE showing accelerated thinning at older ages. Overall, children in the PAE group showed reduced cortical thinning across time relative to the Comparison participants. Symmetrized percent change (SPC) in CT in several regions was significantly correlated with EF performance at 15-month follow-up for the Comparison group but not the group with PAE.

CONCLUSIONS

Regional differences were seen longitudinally in the trajectory and timing of CT change in children with PAE, suggesting delayed cortical maturation and an atypical pattern of development compared with typically developing individuals. In addition, exploratory correlation analyses of SPC and EF performance suggest the presence of atypical brain-behavior relationships in PAE. The findings highlight the potential role of altered developmental timing of cortical maturation in contributing to long-term functional impairment in PAE.

The impact of prenatal alcohol exposure on gray matter volume and cortical surface area of 2 to 3-year-old children in a South African birth cohort

BACKGROUND

There is a growing literature that demonstrates the effects of prenatal alcohol exposure (PAE) on brain development in school-aged children. Less is known, however, on how PAE impacts the brain early in life. We investigated the effects of PAE and child sex on subcortical gray matter volume, cortical surface area (CSA), cortical volume (CV), and cortical thickness (CT) in children aged 2 to 3 years.

METHODS

The sample was recruited as a nested cross-sectional substudy of the Drakenstein Child Health Study. Images from T1-weighted magnetic resonance imaging were acquired on 47 alcohol-exposed and 124 control children (i.e., with no or minimal alcohol exposure), aged 2 to 3 years, some of whom were scanned as neonates. Brain images were processed through automated processing pipelines using FreeSurfer version 6.0. Subcortical and a priori selected cortical regions of interest were compared.

RESULTS

Subcortical volume analyses revealed a PAE by child sex interaction for bilateral putamen volumes (Left: p = 0.02; Right: p = 0.01). There was no PAE by child sex interaction effect on CSA, CV, and CT. Analyses revealed an impact of PAE on CSA (p = 0.04) and CV (p = 0.04), but not CT in this age group. Of note, the inferior parietal gyrus CSA was significantly smaller in children with PAE compared to control children.

CONCLUSIONS

Findings from this subgroup scanned at age 2 to 3 years build on previously described subcortical volume differences in neonates from this cohort. Findings suggest that PAE persistently affects gray matter development through the critical early years of life. The detectable influence of PAE on brain structure at this early age further highlights the importance of brain imaging studies on the impact of PAE on the young developing brain.

Fetal alcohol spectrum disorder and confabulation in psycholegal settings: A beginner's guide for criminal justice, forensic mental health, and legal interviewers

Fetal alcohol spectrum disorders (FASD) are neurodevelopmental/neurobehavioral conditions caused by prenatal alcohol exposure (PAE). Impairments caused by PAE contribute to the over-representation of individuals with FASD in the United States juvenile and adult criminal justice systems. These same impairments can equally impact on individuals with FASD who are witnesses to or victims of crime who also have to navigate the complexities of the criminal justice system. Difficulties include increased susceptibility to confabulation throughout the legal process that, in turn, can contribute to increased rates of poor outcomes including false confessions and wrongful convictions. Individuals with FASD are particularity at risk of confabulation when they are subjected to tactics, such as stressful and anxiety-provoking situations, threats, and leading, suggestive, or coercive questioning. Many professionals in the forensic context are unfamiliar with FASD or related confabulation risk and may unintentionally utilize tactics that intensify impacts of pre-existing impairment. This article serves as a beginner's guide for professionals working in criminal justice settings by (a) providing research-based overviews of FASD and confabulation, (b) describing how FASD may lead to confabulation, and (c) suggesting ways that professionals can modify protocols when interacting with individuals with FASD. Suggestions in this article hold the potential to decrease the risk of confabulation in the criminal justice system and decrease problematic outcomes, such as false confessions and wrongful convictions among individuals with FASD.

Neurodevelopmental Trajectories Following Prenatal Alcohol Exposure

Prenatal alcohol exposure (PAE) interferes with neurodevelopment. The brain is particularly susceptible to the adverse consequences of prenatal alcohol exposure, and numerous studies have documented changes to brain anatomy and function, as well as consequences for cognition, behavior, and mental health. Studies in typically developing individuals have shown that the brain undergoes dynamic developmental processes over an individual’s lifespan. Furthermore, magnetic resonance imaging (MRI) studies in other neurodevelopmental and psychiatric disorders have shown that their developmental trajectories differ from the typical pattern. Therefore, to understand long-term clinical outcomes of fetal alcohol spectrum disorders (FASD), it is necessary to investigate changes in neurodevelopmental trajectories in this population. Here we review studies that have used MRI to evaluate changes in brain structure and function over time via cross-sectional or longitudinal methods in individuals with PAE. Research demonstrates that individuals with PAE have atypical cortical and white matter microstructural developmental trajectories through childhood and adolescence. More research is needed to understand how factors such as sex and postnatal experiences may further mediate these trajectories. Furthermore, nothing is known about the trajectories beyond young adulthood.

Corticostriatal Circuit Models of Cognitive Impairments Induced by Fetal Exposure to Alcohol

The term fetal alcohol spectrum disorder includes a group of diseases caused by fetal alcohol exposure (FAE). Patients with fetal alcohol spectrum disorder display heterogeneous socioemotional and cognitive deficits, particularly in the domain of executive function, that share symptoms with other neuropsychiatric disorders. Despite the availability of several preclinical models, the developmental brain defects causally linked to behavioral deficits induced by FAE remain poorly understood. Here, we first review the effects of FAE on corticostriatal development and its impact on both corticostriatal pathway function and cognitive abilities. We propose three non-mutually exclusive circuit models of corticostriatal dysfunctions to account for some of the FAE-induced cognitive deficits. One model posits that associative-sensorimotor imbalance causes hyper goal-directed behavior, and a second model implies that alteration of prefrontal-striatal behavioral suppression circuits results in loss of behavioral inhibition. A third model suggests that local striatal circuit deficits affect striatal neuronal ensemble function to impair action selection and performance. Finally, we discuss how preclinical approaches applied to these circuit models could offer potential rescue strategies for executive function deficits in patients with fetal alcohol spectrum disorder.

Disruptions in global network segregation and integration in adolescents and young adults with fetal alcohol spectrum disorder

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is a significant public health problem that is associated with a broad range of physical, neurocognitive, and behavioral effects resulting from prenatal alcohol exposure (PAE). Magnetic resonance imaging (MRI) has been an important tool for advancing our knowledge of abnormal brain structure and function in individuals with FASD. However, whereas only a small number of studies have applied graph theory-based network analysis to resting-state functional MRI (fMRI) data in individuals with FASD additional research in this area is needed.

METHODS

Resting-state fMRI data were collected from adolescent and young adult participants (ages 12-22) with fetal alcohol syndrome (FAS) or alcohol-related neurodevelopmental disorder (ARND) and neurotypically developing controls (CNTRL) from previous studies. Group independent components analysis (gICA) was applied to fMRI data to extract components representing functional brain networks. Functional network connectivity (FNC), measured by Pearson correlation of the average independent component (IC) time series, was analyzed under a graph theory framework to compare network modularity, the average clustering coefficient, characteristic path length, and global efficiency between groups. Cognitive intelligence, measured by the Wechsler Abbreviated Scale of Intelligence (WASI), was compared and correlated to global network measures.

RESULTS

Group comparisons revealed significant differences in the average clustering coefficient, characteristic path length, and global efficiency. Modularity was not significantly different between groups. The FAS and ARND groups scored significantly lower than the CNTRL group on Full Scale IQ (FS-IQ) and the Vocabulary subtest, but not the Matrix Reasoning subtest. No significant associations between intelligence and graph theory measures were detected.

CONCLUSION

Our results partially agree with previous studies examining global graph theory metrics in children and adolescents with FASD and suggest that the exposure to alcohol during prenatal development leads to disruptions in aspects of functional network segregation and integration.

Prenatal Exposure to Tobacco and Alcohol Alters Development of the Neonatal Auditory System

Prenatal exposures to alcohol (PAE) and tobacco (PTE) are known to produce adverse neonatal and childhood outcomes including damage to the developing auditory system. Knowledge of the timing, extent, and combinations of these exposures on effects on the developing system is limited. As part of the physiological measurements from the Safe Passage Study, Auditory Brainstem Responses (ABRs) and Transient Otoacoustic Emissions (TEOAEs) were acquired on infants at birth and one-month of age. Research sites were in South Africa and the Northern Plains of the U.S. Prenatal information on alcohol and tobacco exposure was gathered prospectively on mother/infant dyads. Cluster analysis was used to characterize three levels of PAE and three levels of PTE. Repeated-measures ANOVAs were conducted for newborn and one-month-old infants for ABR peak latencies and amplitudes and TEOAE levels and signal-to-noise ratios. Analyses controlled for hours of life at test, gestational age at birth, sex, site, and other exposure. Significant main effects of PTE included reduced newborn ABR latencies from both ears. PTE also resulted in a significant reduction of ABR peak amplitudes elicited in infants at 1-month of age. PAE led to a reduction of TEOAE amplitude for 1-month-old infants but only in the left ear. Results indicate that PAE and PTE lead to early disruption of peripheral, brainstem, and cortical development and neuronal pathways of the auditory system, including the olivocochlear pathway.

Prenatal ethanol exposure impairs the formation of radial glial fibers and promotes the transformation of GFAPδ‑positive radial glial cells into astrocytes

During embryonic cortical development, radial glial cells (RGCs) are the major source of neurons, and these also serve as a supportive scaffold to guide neuronal migration. Similar to Vimentin, glial fibrillary acidic protein (GFAP) is one of the major intermediate filament proteins present in glial cells. Previous studies confirmed that prenatal ethanol exposure (PEE) significantly affected the levels of GFAP and increased the disassembly of radial glial fibers. GFAPδ is a variant of GFAP that is specifically expressed in RGCs; however, to the best of our knowledge, there are no reports regarding how PEE influences its expression during cortical development. In the present study, the effects of PEE on the expression and distribution of GFAPδ during early cortical development were assessed. It was found that PEE significantly decreased the expression levels of GFAP and GFAPδ. Using double immunostaining, GFAPδ was identified to be specifically expressed in apical and basal RGCs, and was co‑localized with other intermediate filament proteins, such as GFAP, Nestin and Vimentin. Additionally, PEE significantly affected the morphology of radial glial fibers and altered the behavior of RGCs. The loss of GFAPδ accelerated the transformation of RGCs into astrocytes. Using co‑immunostaining with Ki67 or phospho‑histone H3, GFAPδ+ cells were observed to be proliferative or mitotic cells, and ethanol treatment significantly decreased the proliferative or mitotic activities of GFAPδ+ RGCs. Taken together, the results suggested that PEE altered the expression patterns of GFAPδ and impaired the development of radial glial fibers and RGC behavior. The results of the present study provided evidence that GFAPδ may be a promising target to rescue the damage induced by PEE.

Early delay of gratification predicts later inhibitory control and academic performance in children with prenatal alcohol exposure

Fetal alcohol spectrum disorder (FASD) affects 2-5% of the children in the United States. In the preschool age-range, inhibitory deficits frequently manifest as impaired ability to delay gratification, which is associated with deficits in cognitive flexibility in these children. The goal of this longitudinal study was to determine whether the ability to delay gratification in preschool children with FASD is (1) associated with broader manifestations in temperament and behavior; (2) predictive of later inhibitory control, cognitive flexibility and working memory in middle childhood; and (3) predictive of later parent-reported behavioral problems and school functioning in middle childhood. Forty-seven children with FASD, ages 2.5-5 years were administered a delay of gratification task in which they chose between receiving 2 snacks immediately or 10 snacks after waiting for 10 min. Two groups were defined based on a median split of waiting time. Four years later, 29 children completed measures of inhibitory control (Flanker task), cognitive flexibility (Dimensional Change Card Sort Test), and working memory (Stanford-Binet Intelligence Scales), and their parents completed the Child Behavior Checklist as a measure of the child's behavioral problems and school functioning. Children with longer wait times on the delay of gratification task in preschool showed better inhibitory control on the Flanker task in middle childhood and better parent-reported school functioning in English. These findings indicate that early inhibitory capacity persists into middle childhood in those with FASD, and may be a promising target for early intervention to improve later cognitive outcomes in these children.

Current Socioeconomic Status Correlates With Brain Volumes in Healthy Children and Adolescents but Not in Children With Prenatal Alcohol Exposure

Individuals with prenatal alcohol exposure (PAE) exhibit neurological deficits associated with brain injury including smaller brain volumes. Additional risk factors such as lower socioeconomic status (SES) may also have an impact on brain development for this population. This study examined how brain volumes are related to SES in both neurotypically developing children and adolescents, and those with PAE. 3D T1-weighted MPRAGE images were acquired from 69 participants with PAE (13.0 ± 3.2 years, range 7.1–18.8 years, 49% female) and 70 neurotypical controls (12.4 ± 2.9 years, range 7.0–18.5 years, 60% female) from four scanning sites in Canada. SES scores calculated using Hollingshead’s Four-Factor Index of Social Status from current caregiver placement were not significantly different between groups, though more children with PAE had lower SES scores compared to controls. Psychometric data comprised 14 cognitive measures, including executive functioning, attention and working memory, memory, math/numerical ability, and word reading. All cognitive scores were significantly worse in children with PAE compared to controls, though SES was not correlated with cognitive scores in either group after correction for multiple comparisons. All 13 brain volumes were smaller in children with PAE compared to children in the control group. Higher SES was associated with larger hippocampus and amygdala volumes in controls, but there were no such associations in children with PAE. Direct evaluation of the interaction between SES and diagnostic group did not show a significant differential impact of SES on these structures. These findings support previous links between SES and brain volumes in neurotypically developing children, but the lack of such a relationship with SES in children with PAE may be due to the markedly smaller brain volumes resulting from the initial brain injury and postpartum brain development, regardless of later SES.

Tissue Engineering and Biomaterial Strategies to Elicit Endogenous Neuronal Replacement in the Brain

Neurogenesis in the postnatal mammalian brain is known to occur in the dentate gyrus of the hippocampus and the subventricular zone. These neurogenic niches serve as endogenous sources of neural precursor cells that could potentially replace neurons that have been lost or damaged throughout the brain. As an example, manipulation of the subventricular zone to augment neurogenesis has become a popular strategy for attempting to replace neurons that have been lost due to acute brain injury or neurodegenerative disease. In this review article, we describe current experimental strategies to enhance the regenerative potential of endogenous neural precursor cell sources by enhancing cell proliferation in neurogenic regions and/or redirecting migration, including pharmacological, biomaterial, and tissue engineering strategies. In particular, we discuss a novel replacement strategy based on exogenously biofabricated "living scaffolds" that could enhance and redirect endogenous neuroblast migration from the subventricular zone to specified regions throughout the brain. This approach utilizes the first implantable, biomimetic tissue-engineered rostral migratory stream, thereby leveraging the brain's natural mechanism for sustained neuronal replacement by replicating the structure and function of the native rostral migratory stream. Across all these strategies, we discuss several challenges that need to be overcome to successfully harness endogenous neural precursor cells to promote nervous system repair and functional restoration. With further development, the diverse and innovative tissue engineering and biomaterial strategies explored in this review have the potential to facilitate functional neuronal replacement to mitigate neurological and psychiatric symptoms caused by injury, developmental disorders, or neurodegenerative disease.

Radiological Findings on Structural Magnetic Resonance Imaging in Fetal Alcohol Spectrum Disorders and Healthy Controls

BACKGROUND

Fetal alcohol spectrum disorders (FASD) describe a range of physical, behavioral, and cognitive impairments stemming from prenatal alcohol exposure (PAE). Although case studies have demonstrated striking visible brain abnormalities in humans (enlargement of the lateral ventricles, thinning or absence of the corpus callosum, etc.), few studies have systematically determined how these radiological findings generalize to the wider population of individuals living with FASD.

METHODS

This study examines rates of structural brain anomalies on magnetic resonance imaging (MRI) as determined by 2 radiologists in a retrospective blinded review of 163 controls and 164 individuals with PAE who were previously scanned as participants of past research studies. Incidental findings were categorized as normal variants, nonclinically significant incidental findings, or clinically significant incidental findings. Rates were compared between diagnostic subgroups using chi-square analysis.

RESULTS

There was no significant difference in the overall rate of incidental findings between groups: 75% of controls and 73% of PAE participants had no incidental findings of any kind, and only 1% of controls and 3% of PAE participants had incidental finding of clinical significance (the remaining findings were considered nonsignificant anomalies or normal variants). When the PAE group was split by diagnosis, low-lying cerebellar tonsils, polymicrogyria, and ventricular asymmetry/enlargement were all most prevalent in subjects with fetal alcohol syndrome/partial fetal alcohol syndrome. In addition, the overall rate of incidental findings was higher (41%) in participants with FAS/pFAS, compared to 25% in controls. No participants in this relatively large sample had corpus callosum agenesis.

CONCLUSIONS

Although advanced quantitative MRI research has uncovered a range of differences in brain structure associated with FASD, this qualitative radiological study suggests that routine clinical MRI does not reveal a consistent pattern of brain abnormalities that can be used diagnostically in this population.

The Impact of Paternal Alcohol Consumption on Offspring Brain and Behavioral Development

BACKGROUND

Fetal alcohol spectrum disorders (FASD) describe the wide array of long-lasting developmental abnormalities in offspring due to prenatal alcohol (ethanol [EtOH]) exposure via maternal gestational drinking. Although the teratogenic consequences of prenatal EtOH exposure, are apparent, the effects of preconception paternal EtOH exposure (PatEE) are still unclear. Previous research suggests that PatEE can induce molecular changes and abnormal behavior in the offspring. However, it is not known whether PatEE impacts the development of the neocortex and behavior in offspring as demonstrated in maternal consumption models of FASD (J Neurosci, 33, 2013, 18893).

METHODS

In this study, we utilized a novel mouse model of PatEE where male mice self-administered 25% EtOH for an extended period prior to conception, generating indirect exposure to the offspring through the paternal germline. Following mating, we examined the effects of PatEE on offspring neocortical development at postnatal day (P) 0 and evaluated several aspects of behavior at both P20 and P30 using a battery of behavioral assays.

RESULTS

PatEE resulted in significant impact on neocortical development, including abnormal patterns of gene expression within the neocortex at P0 and subtle alterations in patterns of intraneocortical connections. Additionally, PatEE mice exhibited a sex-specific increase in activity and sensorimotor integration deficits at P20, and decreased balance, coordination, and short-term motor learning at P30. This suggests that PatEE may generate long-lasting, sex-specific effects on offspring behavior.

CONCLUSIONS

These results demonstrate that the developmental impact of preconception PatEE is more harmful than previously thought and provide additional insights into the biological mechanisms that may underlie atypical behavior observed in children of alcoholic fathers.

The brain's functional connectome in young children with prenatal alcohol exposure

Prenatal alcohol exposure (PAE) can lead to altered brain function and structure, as well as lifelong cognitive, behavioral, and mental health difficulties. Previous research has shown reduced brain network efficiency in older children and adolescents with PAE, but no imaging studies have examined brain differences in young children with PAE, at an age when cognitive and behavioral problems often first become apparent. The present study aimed to investigate the brain's functional connectome in young children with PAE using passive viewing fMRI. We analyzed 34 datasets from 26 children with PAE aged 2-7 years and 215 datasets from 87 unexposed typically-developing children in the same age range. The whole brain functional connectome was constructed using functional connectivity analysis across 90 regions for each dataset. We examined intra- and inter-participant stability of the functional connectome, graph theoretical measurements, and their correlations with age. Children with PAE had similar inter- and intra-participant stability to controls. However, children with PAE, but not controls, showed increasing intra-participant stability with age, suggesting a lack of variability of intrinsic brain activity over time. Inter-participant stability increased with age in controls but not in children with PAE, indicating more variability of brain function across the PAE population. Global graph metrics were similar between children with PAE and controls, in line with previous studies in older children. This study characterizes the functional connectome in young children with PAE for the first time, suggesting that the increased brain variability seen in older children develops early in childhood, when participants with PAE fail to show the expected age-related increases in inter-individual stability.

Glucocorticoid receptor expression in the stress-limbic circuitry is differentially affected by prenatal alcohol exposure and adolescent stress

The dense expression of glucocorticoid receptors (GR) within the amygdala, medial prefrontal cortex (mPFC) and paraventricular nucleus of hypothalamus (PVN) mediates many aspects of emotional and stress regulation. Importantly, both prenatal alcohol exposure (PAE) and adolescent stress are known to induce emotional and stress dysregulation. Little is known, however, about how PAE and/or adolescent stress may alter the expression of GR in the amygdala, mPFC, and PVN. To fill this gap, we exposed PAE and control adolescent male and female rats to chronic mild stress (CMS) and assessed GR mRNA expression in the amygdala, mPFC, and PVN immediately following stress or in adulthood. We found that the effects of PAE on GR expression were more prevalent in the amygdala, while effects of adolescent stress on GR expression were more prevalent in the mPFC. Moreover, PAE effects in the amygdala were more pronounced during adolescence and adolescent stress effects in the mPFC were more pronounced in adulthood. GR expression in the PVN was affected by both PAE and adolescent stress. Finally, PAE and/or adolescent stress effects were distinct between males and females. Together, these results suggest that PAE and adolescent CMS induce dynamic alterations in GR expression in the amygdala, mPFC, and PVN, which manifest differently depending on the brain area, age, and sex of the animal. Additionally, these data indicate that PAE-induced hyperresponsiveness to stress and increased vulnerability to mental health problems may be mediated by different neural mechanisms depending on the sex and age of the animal.

Altered Functional Connectivity Observed at Rest in Children and Adolescents Prenatally Exposed to Alcohol

Studies of brain structure in fetal alcohol spectrum disorder (FASD) have shown the global and focal effects that prenatal alcohol exposure (PAE) has on the brain, suggesting but not measuring altered function in FASD. This study aimed to (1) identify resting-state functional networks in children and adolescents with FASD, (2) investigate functional connectivity differences compared with healthy controls, and (3) assess the links to cognitive deficits. Participants included 66 children/adolescents with FASD (aged 5.5-18.9 years) and 67 healthy controls (aged 5.8-18.5 years) scanned across four sites as part of the NeuroDevNet study. Six core functional networks with 27 regions of interest (ROIs) were examined using seed-based and ROI-to-ROI analyses. Average seed-based connectivity maps showed significant spatial overlap of positively correlated regions for all six core networks between FASD and controls, but there was less overlap for negatively correlated regions. ROI-to-ROI matrices demonstrated lower internetwork connectivity between regions primarily associated with the salience network (anterior cingulate cortex and bilateral insula), frontal-parietal network (bilateral posterior parietal cortex), and language network (right posterior superior temporal gyrus). Post hoc correlations of the FASD participants without medication revealed a relationship between functional connectivity and performance on two cognitive tests associated with mathematics ability and attention. Even though participants with PAE exhibit very similar intranetwork functional connectivity patterns as controls, their lower internetwork functional connectivity suggests underlying deficits in the functional network brain architecture that may be related to cognitive impairment.

Neural correlates of verbal memory in youth with heavy prenatal alcohol exposure

Prenatal alcohol exposure can impact both brain development and neurobehavioral function, including verbal learning and recall, although the relation between verbal recall and brain structure in this population has not been examined fully. We aimed to determine the structural neural correlates of verbal learning and recall in youth with histories of heavy prenatal alcohol exposure using a region of interest (ROI) approach. As part of an ongoing multisite project, subjects (age 10-16 years) with prenatal alcohol exposure (AE, n = 81) and controls (CON, n = 81) were tested using the CVLT-C and measures of cortical volume, surface area, and thickness as well as hippocampal volume were derived from MRI. Group differences in brain and memory indices were tested with ANOVA. Multiple regression analyses tested whether brain ROIs significantly predicted memory performance. The AE group had lower scores than the CON group on all CVLT-C variables (ps ≤ .001) and volume and surface area (ps < .025), although results varied by ROI. No group differences in cortical thickness were found. The relations between cortical structure and memory performance differed between group among some ROIs, particularly those in the frontal cortex, generally with smaller surface area and/or thinner cortex predicting better performance in CON but worse performance in AE. Cortical surface area appears to be the most sensitive index to the effects of prenatal alcohol exposure, while cortical thickness appears to be the least sensitive. These findings also indicate that the neural correlates of verbal memory are altered in youth with heavy prenatal alcohol exposure compared to controls.

White matter microstructure in fetal alcohol spectrum disorders: A systematic review of diffusion tensor imaging studies

Diffusion tensor imaging (DTI) has revolutionized our understanding of the neural underpinnings of alcohol teratogenesis. This technique can detect alterations in white matter in neurodevelopmental disorders, such as fetal alcohol spectrum disorder (FASD). Using Prisma guidelines, we identified 23 DTI studies conducted on individuals with prenatal alcohol exposure (PAE). These studies confirm the widespread nature of brain damage in PAE by reporting diffusivity alterations in commissural, association, and projection fibers; and in relation to increasing cognitive impairment. Reduced integrity in terms of lower fractional anisotropy (FA) and higher mean diffusivity (MD) and radial diffusivity (RD) is reported more consistently in the corpus callosum, cerebellar peduncles, cingulum, and longitudinal fasciculi connecting frontal and temporoparietal regions. Although these interesting results provide insight into FASD neuropathology, it is important to investigate the clinical diversity of this disorder for better treatment options and prediction of progression. The aim of this review is to provide a summary of different patterns of neural structure between PAE and typically developed individuals. We further discuss the association of alterations in diffusivity with demographic features and symptomatology of PAE. With the accumulated knowledge of the neural correlates of FASD presenting symptoms, a comprehensive understanding of the heterogeneity in FASD will potentially improve the disease management and will highlight the diagnostic challenges and potential areas of future research avenues, where neural markers may be beneficial.

Two-year cortical trajectories are abnormal in children and adolescents with prenatal alcohol exposure

OBJECTIVES

Cortical abnormalities in prenatal alcohol exposure (PAE) are known, including in gyrification (LGI), thickness (CT), volume (CV), and surface area (CS). This study provides longitudinal and developmental context to the PAE cortical development literature.

EXPERIMENTAL DESIGN

Included: 58 children with PAE and 52 controls, ages 6-17 at enrollment, from four Collaborative Initiative on FASD (CIFASD) sites. Participants underwent a formal evaluation of physical anomalies and dysmorphic facial features associated with PAE. MRI data were collected on three platforms (Siemens, GE, and Philips) at four sites. Scans were spaced two years apart. Change in LGI, CT, CS, and CV were examined.

PRINCIPAL OBSERVATIONS

Several significant regional age-by-diagnosis linear and quadratic interaction effects in LGI, CT, and CV were found, indicating atypical developmental trajectories in PAE. No significant correlations were observed between cortical measures and IQ.

CONCLUSIONS

Regional differences were seen longitudinally in CT, CV, and LGI in those with PAE. The findings represent important insights into developmental trajectories and may have implications for the timing of assessments and interventions in this population. It is noteworthy that cortical metrics did not correlate with IQ, suggesting that more specific aspects of cognitive development may need to be explored to provide further context.

Preliminary Findings that a Targeted Intervention Leads to Altered Brain Function in Children with Fetal Alcohol Spectrum Disorder

Children with fetal alcohol spectrum disorder (FASD) exhibit behavioral dysregulation, executive dysfunction, and atypical function in associated brain regions. Previous research shows early intervention mitigates these outcomes but corresponding brain changes were not studied. Given the Alert^® Program for Self-Regulation improves behavioral regulation and executive function in children with FASD, we asked if this therapy also improves their neural functioning in associated regions. Twenty-one children with FASD aged 8–12 years were randomized to the Alert^®-treatment (TXT; n = 10) or waitlist-control (WL; n = 11) conditions. They were assessed with a Go-NoGo functional magnetic resonance imaging (fMRI) paradigm before and after training or the wait-out period. Groups initially performed equivalently and showed no fMRI differences. At post-test, TXT outperformed WL on NoGo trials while fMRI in uncorrected results with a small-volume correction showed less activation in prefrontal, temporal, and cingulate regions. Groups also demonstrated different patterns of change over time reflecting reduced signal at post-test in selective prefrontal and parietal regions in TXT and increased in WL. In light of previous evidence indicating TXT at post-test perform similar to non-exposed children on the Go-NoGo fMRI paradigm, our findings suggest Alert^® does improve functional integrity in the neural circuitry for behavioral regulation in children with FASD.

Fine motor skills in a population of children in remote Australia with high levels of prenatal alcohol exposure and Fetal Alcohol Spectrum Disorder

BACKGROUND

Many children in the remote Fitzroy Valley region of Western Australia have prenatal alcohol exposure (PAE). Individuals with PAE can have neurodevelopmental impairments and be diagnosed with one of several types of Fetal Alcohol Spectrum Disorder (FASD). Fine motor skills can be impaired by PAE, but no studies have developed a comprehensive profile of fine motor skills in a population-based cohort of children with FASD. We aimed to develop a comprehensive profile of fine motor skills in a cohort of Western Australian children; determine whether these differed in children with PAE or FASD; and establish the prevalence of impairment.

METHODS

Children (n = 108, 7 to 9 years) were participants in a population-prevalence study of FASD in Western Australia. Fine motor skills were assessed using the Bruininks-Oseretsky Test of Motor Proficiency, which provided a Fine Motor Composite score, and evaluated Fine Manual Control (Fine Motor Precision; Fine Motor Integration) and Manual Coordination (Manual Dexterity; Upper-Limb Coordination). Descriptive statistics were reported for the overall cohort; and comparisons made between children with and without PAE and/or FASD. The prevalence of severe (≤ 2nd percentile) and moderate (≤16th percentile) impairments was determined.

RESULTS

Overall, Fine Motor Composite scores were 'average' (M = 48.6 ± 7.4), as were Manual Coordination (M = 55.7 ± 7.9) and Fine Manual Control scores (M = 42.5 ± 6.2). Children with FASD had significantly lower Fine Motor Composite (M = 45.2 ± 7.7 p = 0.046) and Manual Coordination scores (M = 51.8 ± 7.3, p = 0.027) than children without PAE (Fine Motor Composite M = 49.8 ± 7.2; Manual Coordination M = 57.0 ± 7.7). Few children had severe impairment, but rates of moderate impairment were very high.

CONCLUSIONS

Different types of fine motor skills should be evaluated in children with PAE or FASD. The high prevalence of fine motor impairment in our cohort, even in children without PAE, highlights the need for therapeutic intervention for many children in remote communities.

Localized reductions in resting-state functional connectivity in children with prenatal alcohol exposure

Fetal alcohol spectrum disorders (FASD) are characterized by impairment in cognitive function that may or may not be accompanied by craniofacial anomalies, microcephaly, and/or growth retardation. Resting-state functional MRI (rs-fMRI), which examines the low-frequency component of the blood oxygen level dependent (BOLD) signal in the absence of an explicit task, provides an efficient and powerful mechanism for studying functional brain networks even in low-functioning and young subjects. Studies using independent component analysis (ICA) have identified a set of resting-state networks (RSNs) that have been linked to distinct domains of cognitive and perceptual function, which are believed to reflect the intrinsic functional architecture of the brain. This study is the first to examine resting-state functional connectivity within these RSNs in FASD. Rs-fMRI scans were performed on 38 children with FASD (19 with either full fetal alcohol syndrome (FAS) or partial FAS (PFAS), 19 nonsyndromal heavily exposed (HE)), and 19 controls, mean age 11.3 ± 0.9 years, from the Cape Town Longitudinal Cohort. Nine resting-state networks were generated by ICA. Voxelwise group comparison between a combined FAS/PFAS group and controls revealed localized dose-dependent functional connectivity reductions in five regions in separate networks: anterior default mode, salience, ventral and dorsal attention, and R executive control. The former three also showed lower connectivity in the HE group. Gray matter connectivity deficits in four of the five networks appear to be related to deficits in white matter tracts that provide intra-RSN connections. Hum Brain Mapp 38:5217-5233, 2017. © 2017 Wiley Periodicals, Inc.

Preserved cortical asymmetry despite thinner cortex in children and adolescents with prenatal alcohol exposure and associated conditions

Prenatal alcohol exposure (PAE) is associated with reduced overall brain volume. Although this has been reported consistently across studies, the status of cortical thickness after PAE is more variable. The cortex is asymmetric in typical controls, but it is unclear whether the left and right counter parts of the cortical gray matter are unevenly influenced in postpartum brain development after PAE. Brain MRI was acquired in a newly recruited sample of 157 participants (PAE: N = 78, 5.5-18.9 years, 40 females and controls: N = 79, 5.8-18.5 years, 44 females) across four Canadian sites in the NeuroDevNet project. The PAE group had other confounds such as psychiatric co-morbidity, different living environment, and so on, not present in the control group. In agreement with previous studies, the volumes of all brain structures were reduced in PAE compared to controls, including gray and white matter of cerebrum and cerebellum, and all deep gray matter including the hippocampus, amygdala, thalamus, caudate, putamen, and pallidum. The PAE group showed reductions in global and regional cortical thickness, while the pattern and degree of cortical thickness asymmetry were preserved in PAE participants with the greatest rightward asymmetry in the lateral parietal lobe and the greatest leftward asymmetry in the lateral frontal cortex. This persistent asymmetry reflects that the homologous left and right cortical regions followed typical relative developmental patterns in the PAE group despite being thinner bilaterally than controls. Hum Brain Mapp 39:72-88, 2018. © 2017 Wiley Periodicals, Inc.

Prefrontal cortical responses in children with prenatal alcohol-related neurodevelopmental impairment: A functional near-infrared spectroscopy study

OBJECTIVE

Disruption in the neural activation of the prefrontal cortex (PFC) in modulating arousal was explored in children with heavy prenatal alcohol exposure (PAE), who have known neurobehavioral impairment.

METHODS

During a task that elicits frustration, functional near-infrared spectroscopy (fNIRS) was used to measure PFC activation, specifically levels of oxygenated (HBO) and deoxygenated (HBR) hemoglobin, in children with PAE (n=18) relative to typically developing Controls (n=12) and a Clinical Contrast group with other neurodevelopmental or behavioral problems (n=14).

RESULTS

Children with PAE had less activation during conditions with positive emotional arousal, as indicated by lower levels of HBO in the medial areas of the PFC and higher levels of HBR in all areas of the PFC sampled relative to both other groups. Children in the Control group demonstrated greater differentiation of PFC activity than did children with PAE. Children in the Clinical Contrast group demonstrated the greatest differences in PFC activity between valences of task conditions.

CONCLUSIONS

Specific patterns of PFC activation differentiated children with PAE from typically developing children and children with other clinical problems.

SIGNIFICANCE

FNIRS assessments of PFC activity provide new insights regarding the mechanisms of commonly seen neurobehavioral dysfunction in children with PAE.

Genome-wide profiling of differentially spliced mRNAs in human fetal cortical tissue exposed to alcohol

Excessive alcohol consumption results in significant changes in gene expression and isoforms due to altered mRNA splicing. As such, an intriguing possibility is that disturbances in alternative splicing are involved in key pathological pathways triggered by alcohol exposure. However, no resources have been available to systematically analyze this possibility at a genome-wide scale. Here, we performed RNA sequencing of human fetal cortical slices that were obtained at the late first trimester and exposed to ethanol or control medium. We report 382 events that were identified as changes affecting the ratio of splicing isoforms in the ethanol-exposed fetal human cortex. Additionally, previously unreported novel isoforms of several genes were also identified. These results provide a broad perspective on the post-transcriptional regulatory network underlying ethanol-induced pathogenesis in the developing human cortex.

Radiological studies of fetal alcohol spectrum disorders in humans and animal models: An updated comprehensive review

Fetal Alcohol Spectrum Disorders encompass a wide range of birth defects in children born to mothers who consumed alcohol during pregnancy. Typical mental impairments in FASD include difficulties in life adaptation and learning and memory, deficits in attention, visuospatial skills, language and speech disabilities, mood disorders and motor disabilities. Multimodal imaging methods have enabled in vivo studies of the teratogenic effects of alcohol on the central nervous system, giving more insight into the FASD phenotype. This paper offers an up-to-date comprehensive review of radiological findings in the central nervous system in studies of prenatal alcohol exposure in both humans and translational animal models, including Magnetic Resonance Imaging, Computed Tomography, Positron Emission Tomography, Single Photon Emission Tomography and Ultrasonography.

Sexual dimorphism of volume reduction but not cognitive deficit in fetal alcohol spectrum disorders: A combined diffusion tensor imaging, cortical thickness and brain volume study

Quantitative magnetic resonance imaging (MRI) has revealed abnormalities in brain volumes, cortical thickness and white matter microstructure in fetal alcohol spectrum disorders (FASD); however, no study has reported all three measures within the same cohort to assess the relative magnitude of deficits, and few studies have examined sex differences. Participants with FASD (n = 70; 30 females; 5-32 years) and healthy controls (n = 74; 35 females; 5-32 years) underwent cognitive testing and MRI to assess cortical thickness, regional brain volumes and fractional anisotropy (FA)/mean diffusivity (MD) of white matter tracts. A significant effect of group, age-by-group, or sex-by-group was found for 9/9 volumes, 7/39 cortical thickness regions, 3/9 white matter tracts, and 9/10 cognitive tests, indicating group differences that in some cases differ by age or sex. Volume reductions for several structures were larger in males than females, despite similar deficits of cognition in both sexes. Correlations between brain structure and cognitive scores were found in females of both groups, but were notably absent in males. Correlations within a given MRI modality (e.g. total brain volume and caudate volume) were prevalent in both the control and FASD groups, and were more numerous than correlations between measurement types (e.g. volumes and diffusion tensor imaging) in either cohort. This multi-modal MRI study finds widespread differences of brain structure in participants with prenatal alcohol exposure, and to a greater extent in males than females which may suggest attenuation of the expected process of sexual dimorphism of brain structure during typical development.

DNA Methylation program in normal and alcohol-induced thinning cortex

While cerebral underdevelopment is a hallmark of fetal alcohol spectrum disorders (FASD), the mechanism(s) guiding the broad cortical neurodevelopmental deficits are not clear. DNA methylation is known to regulate early development and tissue specification through gene regulation. Here, we examined DNA methylation in the onset of alcohol-induced cortical thinning in a mouse model of FASD. C57BL/6 (B6) mice were administered a 4% alcohol (v/v) liquid diet from embryonic (E) days 7-16, and their embryos were harvested at E17, along with isocaloric liquid diet and lab chow controls. Cortical neuroanatomy, neural phenotypes, and epigenetic markers of methylation were assessed using immunohistochemistry, Western blot, and methyl-DNA assays. We report that cortical thickness, neuroepithelial proliferation, and neuronal migration and maturity were found to be deterred by alcohol at E17. Simultaneously, DNA methylation, including 5-methylcytosine (5mC) and 5-hydroxcylmethylcytosine (5hmC), which progresses as an intrinsic program guiding normal embryonic cortical development, was severely affected by in utero alcohol exposure. The intricate relationship between cortical thinning and this DNA methylation program disruption is detailed and illustrated. DNA methylation, dynamic across the multiple cortical layers during the late embryonic stage, is highly disrupted by fetal alcohol exposure; this disruption occurs in tandem with characteristic developmental abnormalities, ranging from structural to molecular. Finally, our findings point to a significant question for future exploration: whether epigenetics guides neurodevelopment or whether developmental conditions dictate epigenetic dynamics in the context of alcohol-induced cortical teratogenesis.

Differentiating the Effects of Familial Risk for Alcohol Dependence and Prenatal Exposure to Alcohol on Offspring Brain Morphology

BACKGROUND

Offspring with a family history of alcohol dependence (AD) have been shown to have altered structural and functional integrity of corticolimbic brain structures. Similarly, prenatal exposure to alcohol is associated with a variety of structural and functional brain changes. The goal of this study was to differentiate the brain gray matter volumetric differences associated with familial risk and prenatal exposure to alcohol among offspring while controlling for lifetime personal exposures to alcohol and drugs.

METHODS

A total of 52 high-risk (HR) offspring from maternal multiplex families with a high proportion of AD were studied along with 55 low-risk (LR) offspring. Voxel-based morphometric analysis was performed using statistical parametric mapping (SPM8) software using 3T structural images from these offspring to identify gray matter volume differences associated with familial risk and prenatal exposure.

RESULTS

Significant familial risk group differences were seen with HR males showing reduced volume of the left inferior temporal, left fusiform, and left and right insula regions relative to LR males, controlling for prenatal exposure to alcohol drugs and cigarettes. HR females showed a reduction in the right fusiform but also showed a reduction in volume in portions of the cerebellum (left crus I and left lobe 8). Prenatal alcohol exposure effects, assessed within the familial HR group, was associated with reduced right middle cingulum and left middle temporal volume. Even low exposure resulting from mothers drinking in amounts less than the median of those who drank (53 drinks or less over the course of the pregnancy) showed a reduction in volume in the right anterior cingulum and in the left cerebellum (lobes 4 and 5).

CONCLUSIONS

Familial risk for AD and prenatal exposure to alcohol and other drugs show independent effects on brain morphology.

Laterality of Brain Activation for Risk Factors of Addiction

Background:

Laterality of brain activation is reported for tests of risk factors of addiction - impulsivity and craving - but authors rarely address the potential significance of those asymmetries.

Objective:

The purpose of this study is to demonstrate this laterality and discuss its relevance to cognitive and neurophysiological asymmetries associated with drug abuse vulnerability in order to provide new insights for future research in drug abuse.

Method:

From published reports, brain areas of activation for two tests of response inhibition or craving for drugs of abuse were compiled from fMRI activation peaks and were tabulated for eight sections (octants) in each hemisphere. Percent asymmetries were calculated (R-L/R+L) across studies for each area.

Results:

For impulsivity, most activation peaks favored the right hemisphere. Overall, the percent difference was 32% (Χ² = 16.026; p < 0.0001) with the greater asymmetry for anterior peaks (46.8%; Χ² = 17.329; p < 0.0001). The asymmetries for cue-induced craving were opposite, favoring the left hemisphere by 6.7% (Χ² = 4.028; p < 0.05). The consistency of left asymmetry was found for almost all drugs. For nicotine, studies where subjects were not allowed to smoke (deprived) prior to measurement had the same left hemisphere activation but those who smoked (satiated) before the fMRI measure showed right asymmetry.

Conclusion:

Brain activation studies demonstrate different left/right hemispheric contributions for impulsivity versus craving - factors related to addiction. Failure to take laterality into consideration is a missed opportunity in designing studies and gaining insight into the etiology of drug abuse and pathways for treatment.

Neurotrophins in the Brain: Interaction With Alcohol Exposure During Development

Fetal alcohol spectrum disorders (FASDs) are a result of the teratogenic effects of alcohol on the developing fetus. Decades of research examining both individuals with FASDs and animal models of developmental alcohol exposure have revealed the devastating effects of alcohol on brain structure, function, behavior, and cognition. Neurotrophic factors have an important role in guiding normal brain development and cellular plasticity in the adult brain. This chapter reviews the current literature showing that alcohol exposure during the developmental period impacts neurotrophin production and proposes avenues through which alcohol exposure and neurotrophin action might interact. These areas of overlap include formation of long-term potentiation, oxidative stress processes, neuroinflammation, apoptosis and cell loss, hippocampal adult neurogenesis, dendritic morphology and spine density, vasculogenesis and angiogenesis, and behaviors related to spatial memory, anxiety, and depression. Finally, we discuss how neurotrophins have the potential to act in a compensatory manner as neuroprotective molecules that can combat the deleterious effects of in utero alcohol exposure.

The Impact of Prenatal Ethanol Exposure on Neuroanatomical and Behavioral Development in Mice

BACKGROUND

In utero alcohol, or ethanol (EtOH), exposure produces developmental abnormalities in the brain of the fetus, which can result in lifelong behavioral abnormalities. Fetal alcohol spectrum disorders (FASD) is a term used to describe a range of adverse developmental conditions caused by EtOH exposure during gestation. Children diagnosed with FASD potentially exhibit a host of phenotypes including growth retardation, facial dysmorphology, central nervous system anomalies, abnormal behavior, and cognitive deficits. Previous research suggests that abnormal gene expression and circuitry in the neocortex may underlie reported disabilities of learning, memory, and behavior resulting from early exposure to alcohol (J Neurosci, 33, 2013, 18893).

METHODS

Here, we utilize a mouse model of FASD to examine effects of prenatal EtOH exposure (PrEE), on brain anatomy in newborn (postnatal day [P]0), weanling (P20), and early adult (P50) mice. We correlate abnormal cortical and subcortical anatomy with atypical behavior in adult P50 PrEE mice. In this model, experimental dams self-administered a 25% EtOH solution throughout gestation (gestational days 0 to 19, day of birth), generating the exposure to the offspring.

RESULTS

Results from these experiments reveal long-term alterations to cortical anatomy, including atypical developmental cortical thinning, and abnormal subcortical development as a result of in utero EtOH exposure. Furthermore, offspring exposed to EtOH during the prenatal period performed poorly on behavioral tasks measuring sensorimotor integration and anxiety.

CONCLUSIONS

Insight from this study will help provide new information on developmental trajectories of PrEE and the biological etiologies of abnormal behavior in people diagnosed with FASD.

Relationships between Head Circumference, Brain Volume and Cognition in Children with Prenatal Alcohol Exposure

Head circumference is used together with other measures as a proxy for central nervous system damage in the diagnosis of fetal alcohol spectrum disorders, yet the relationship between head circumference and brain volume has not been investigated in this population. The objective of this study is to characterize the relationship between head circumference, brain volume and cognitive performance in a large sample of children with prenatal alcohol exposure (n = 144) and healthy controls (n = 145), aged 5-19 years. All participants underwent magnetic resonance imaging to yield brain volumes and head circumference, normalized to control for age and sex. Mean head circumference, brain volume, and cognitive scores were significantly reduced in the prenatal alcohol exposure group relative to controls, albeit with considerable overlap between groups. Males with prenatal alcohol exposure had reductions in all three measures, whereas females with prenatal alcohol exposure had reduced brain volumes and cognitive scores, but no difference in head circumference relative to controls. Microcephaly (defined here as head circumference ≤ 3rd percentile) occurred more often in prenatal alcohol exposed participants than controls, but 90% of the exposed sample had head circumferences above this clinical cutoff indicating that head circumference is not a sensitive marker of prenatal alcohol exposure. Normalized head circumference and brain volume were positively correlated in both groups, and subjects with very low head circumference typically had below-average brain volumes. Conversely, over half of the subjects with very low brain volumes had normal head circumferences, which may stem from differential effects of alcohol on the skeletal and nervous systems. There were no significant correlations between head circumference and any cognitive score. These findings confirm group-level reductions in head circumference and increased rates of microcephaly in children with prenatal alcohol exposure, but raise concerns about the predictive value of this metric at an individual-subject level.

Preliminary Findings Show Maternal Hypothyroidism May Contribute to Abnormal Cortical Morphology in Offspring

In rodents, insufficient thyroid hormone (TH) gestationally has adverse effects on cerebral cortex development. Comparable studies of humans examining how TH insufficiency affects cortical morphology are limited to children with congenital hypothyroidism or offspring of hypothyroxinemic women; effects on cortex of children born to women with clinically diagnosed hypothyroidism are not known. We studied archived MRI scans from 22 children aged 10-12 years born to women treated for preexisting or de novo hypothyroidism in pregnancy (HYPO) and 24 similar age and sex controls from euthyroid women. FreeSurfer Image Analysis Suite software was used to measure cortical thickness (CT) and a vertex-based approach served to compare HYPO versus control groups and Severe versus Mild HYPO subgroups as well as to perform regression analyses examining effects of trimester-specific maternal TSH on CT. Results showed that relative to controls, HYPO had multiple regions of both cortical thinning and thickening, which differed for left and right hemispheres. In HYPO, thinning was confined to medial and mid-lateral regions of each hemisphere and thickening to superior regions (primarily frontal) of the left hemisphere and inferior regions (particularly occipital and temporal) of the right. The Severe HYPO subgroup showed more thinning than Mild in frontal and temporal regions and more thickening in bilateral posterior and frontal regions. Maternal TSH values predicted degree of thinning and thickening within multiple brain regions, with the pattern and direction of correlations differing by trimester. Notably, some correlations remained when cases born to women with severe hypothyroidism were removed from the analyses, suggesting that mild variations of maternal TH may permanently affect offspring cortex. We conclude that maternal hypothyroidism during pregnancy has long-lasting manifestations on the cortical morphology of their offspring with specific effects reflecting both severity and timing of maternal TH insufficiency.

Alcohol exposure in utero is associated with decreased gray matter volume in neonates

Neuroimaging studies have indicated that prenatal alcohol exposure is associated with alterations in the structure of specific brain regions. However, the temporal specificity of such changes and their behavioral consequences are less known. Here we explore the brain structure of infants with in utero exposure to alcohol shortly after birth. T2 structural MRI images were acquired from 28 alcohol-exposed infants and 45 demographically matched healthy controls at 2-4 weeks of age on a 3T Siemens Allegra system as part of large birth cohort study, the Drakenstein Child Health Study (DCHS). Neonatal neurobehavior was assessed at this visit; early developmental outcome assessed on the Bayley Scales of Infant Development III at 6 months of age. Volumes of gray matter regions were estimated based on the segmentations of the University of North Carolina neonatal atlas. Significantly decreased total gray matter volume was demonstrated for the alcohol-exposed cohort compared to healthy control infants (p < 0.001). Subcortical gray matter regions that were significantly different between groups after correcting for overall gray matter volume included left hippocampus, bilateral amygdala and left thalamus (p < 0.01). These findings persisted even when correcting for infant age, gender, ethnicity and maternal smoking status. Both early neurobehavioral and developmental adverse outcomes at 6 months across multiple domains were significantly associated with regional volumes primarily in the temporal and frontal lobes in infants with prenatal alcohol exposure. Alcohol exposure during the prenatal period has potentially enduring neurobiological consequences for exposed children. These findings suggest the effects of prenatal alcohol exposure on brain growth is present very early in the first year of life, a period during which the most rapid growth and maturation occurs.

Executive function and cortical thickness in youths prenatally exposed to cocaine, alcohol and tobacco

Small and detrimental, albeit inconsistent, effects of prenatal cocaine exposure (PCE) during early childhood have been reported. The teratogenic effects of prenatal alcohol (PAE) and tobacco exposure (PTE) on neurobehavior are more firmly established than PCE. We tested if co-exposure to all three drugs could be related to greater differences in brain structure than exposure to cocaine alone. Participants (n=42, PCE=27; age range=14-16 years) received an executive function battery prior to a T1-weighted 3T structural MRI scan. Cortical thickness was measured using FreeSurfer (v5.1). Fetal drug exposure was quantified through maternal self-reports usage during pregnancy. Using general linear modeling, we found no main effects of PCE on cortical thickness, but significant main effects of PAE and PTE in superior and medial frontal regions, after co-varying for the effects of age, sex, and each drug of exposure. Significant alcohol-by-tobacco interactions, and significant cocaine-by-alcohol interactions on cortical thickness in medial parietal and temporal regions were also observed. Poly-drug exposure and cognitive function also showed significant interactions with cortical thickness: lower cortical thickness was associated with better performance in PCE-exposed adolescents. Results suggest that although children with PCE have subtle but persistent brain cortical differences until mid-to-late adolescence.

Increased spontaneous neuronal activity in structurally damaged cortex is correlated with early motor recovery in patients with subcortical infarction

BACKGROUND AND PURPOSE

Secondary cortical thinning and volumetric atrophy in the motor-related cortex can inhibit early functional recovery after subcortical infarction. However, the relationship between the spontaneous neuronal activity in these cortices and motor recovery in patients with focal cerebral infarct remains unknown.

METHODS

Structural magnetic resonance imaging (MRI) and resting-state functional MRI were conducted 1, 4 and 12 weeks after onset in 22 patients with an acute subcortical infarct and in 22 normal subjects. Group differences in cortical thickness and in the amplitude of low-frequency fluctuation (ALFF) in motor-related areas were evaluated, and the relationships between ALFF, cortical thickness changes and changes in the Fugl-Meyer scores of physical performance were further analyzed.

RESULTS

In patients with subcortical infarction, progressively decreasing cortical thickness was found over the observation period ipsilesionally in the primary motor cortex (PMC), supplementary motor cortex (SMC) and precuneus (all P < 0.05). Contralesionally, progressive increases in cortical thickness were detected in SMC and insula (all P < 0.05). Increases in ALFF were observed only in PMC (bilaterally) and only at 12 weeks after stroke (all P < 0.05). The cortical thickness changes in the contralesional SMC (rs = 0.483, P = 0.023) and the ALFF changes in bilateral PMC (ipsilesional, rs = 0.51, P = 0.015; contralesional, rs = 0.463, P = 0.03) were positively correlated with changes in the Fugl-Meyer scores.

CONCLUSIONS

These results suggest that increased spontaneous neuronal activity of the PMC, a region structurally damaged secondarily to ischaemic lesion, may contribute to early motor recovery in patients with subcortical infarction.

Neuroimaging effects of prenatal alcohol exposure on the developing human brain: a magnetic resonance imaging review

OBJECTIVE

This paper reviews the magnetic resonance imaging (MRI) literature on the effects of prenatal alcohol exposure on the developing human brain.

METHOD

A literature search was conducted through the following databases: PubMed, PsycINFO and Google Scholar. Combinations of the following search terms and keywords were used to identify relevant studies: 'alcohol', 'fetal alcohol spectrum disorders', 'fetal alcohol syndrome', 'FAS', 'FASD', 'MRI', 'DTI', 'MRS', 'neuroimaging', 'children' and 'infants'.

RESULTS

A total of 64 relevant articles were identified across all modalities. Overall, studies reported smaller total brain volume as well as smaller volume of both the white and grey matter in specific cortical regions. The most consistently reported structural MRI findings were alterations in the shape and volume of the corpus callosum, as well as smaller volume in the basal ganglia and hippocampi. The most consistent finding from diffusion tensor imaging studies was lower fractional anisotropy in the corpus callosum. Proton magnetic resonance spectroscopy studies are few to date, but showed altered neurometabolic profiles in the frontal and parietal cortex, thalamus and dentate nuclei. Resting-state functional MRI studies reported reduced functional connectivity between cortical and deep grey matter structures. Discussion There is a critical gap in the literature of MRI studies in alcohol-exposed children under 5 years of age across all MRI modalities. The dynamic nature of brain maturation and appreciation of the effects of alcohol exposure on the developing trajectory of the structural and functional network argue for the prioritisation of studies that include a longitudinal approach to understanding this spectrum of effects and potential therapeutic time points.

Selective reduction of cerebral cortex GABA neurons in a late gestation model of fetal alcohol spectrum disorder

Fetal alcohol spectrum disorders (FASD) are associated with cognitive and behavioral deficits, and decreased volume of the whole brain and cerebral cortex. Rodent models have shown that early postnatal treatments, which mimic ethanol toxicity in the third trimester of human pregnancy, acutely induce widespread apoptotic neuronal degeneration and permanent behavioral deficits. However, the lasting cellular and anatomical effects of early ethanol treatments are still incompletely understood. This study examined changes in neocortex volume, thickness, and cellular organization that persist in adult mice after postnatal day 7 (P7) ethanol treatment. Post mortem brain volumes, measured by both MRI within the skull and by fluid displacement of isolated brains, were reduced 10-13% by ethanol treatment. The cerebral cortex showed a similar reduction (12%) caused mainly by lower surface area (9%). In spite of these large changes, several features of cortical organization showed little evidence of change, including cortical thickness, overall neuron size, and laminar organization. Estimates of total neuron number showed a trend level reduction of about 8%, due mainly to reduced cortical volume but unchanged neuron density. However, counts of calretinin (CR) and parvalbumin (PV) subtypes of GABAergic neurons showed a striking >30% reduction of neuron number. Similar ethanol effects were found in male and female mice, and in C57BL/6By and BALB/cJ mouse strains. Our findings indicate that the cortex has substantial capacity to develop normal cytoarchitectonic organization after early postnatal ethanol toxicity, but there is a selective and persistent reduction of GABA cells that may contribute to the lasting cognitive and behavioral deficits in FASD.

Atypical cortical gyrification in adolescents with histories of heavy prenatal alcohol exposure

Prenatal alcohol exposure can adversely affect brain development, although little is known about the effects of prenatal alcohol exposure on gyrification. Gyrification reflects cortical folding complexity and is a process by which the surface of the brain creates sulci and gyri. Prior studies have shown that prenatal alcohol exposure is associated with reduced gyrification in childhood, but no studies have examined adolescents. Subjects (12-16 years) comprised two age-equivalent groups: 30 adolescents with histories of heavy prenatal alcohol exposure (AE) and 19 non-exposed controls (CON). A T1-weighted image was obtained for all participants. Local gyrification index (LGI) was estimated using FreeSurfer. General linear models were used to determine between group differences in LGI controlling for age and sex. Age-by-group interactions were also investigated while controlling for sex. The AE group displayed reduced LGI relative to CON in the bilateral superior parietal region, right postcentral region, and left precentral and lateral occipital regions (ps<.001). Significant age-by-group interactions were observed in the right precentral and lateral occipital regions, and in the left pars opercularis and inferior parietal regions (ps<.01). The AE group showed age-related reductions in gyrification in all regions whereas the CON group showed increased gyrification with age in the lateral occipital region only. While cross-sectional, the age-related reduction in gyrification observed in the AE group suggests alterations in cortical development throughout adolescence and provides further insight into the pathophysiology and brain maturation of adolescents prenatally exposed to alcohol.

Prenatal Alcohol Exposure is Associated with Regionally Thinner Cortex During the Preadolescent Period

Children with fetal alcohol spectrum disorders (FASD) may exhibit craniofacial dysmorphology, neurobehavioral deficits, and reduced brain volume. Studies of cortical thickness in FASD have yielded contradictory findings, with 3 reporting thicker cerebral cortex in frontal and temporal brain regions and 2 showing thinner cortex across multiple regions. All 5 studies included subjects spanning a broad age range, and none have examined continuous measures of prenatal alcohol exposure. We investigated the relation of extent of in utero alcohol exposure to cortical thickness in 78 preadolescent children with FASD and controls within a narrow age range. A whole-brain analysis using FreeSurfer revealed no significant clusters where cortical thickness differed by FASD diagnostic group. However, alcohol dose/occasion during pregnancy was inversely related to cortical thickness in 3 regions-right cuneus/pericalcarine/superior parietal lobe, fusiform/lingual gyrus, and supramarginal/postcentral gyrus. The effect of prenatal alcohol exposure on IQ was mediated by cortical thickness in the right occipitotemporal region. It is noteworthy that a continuous measure of maternal alcohol consumption during pregnancy was more sensitive than FASD diagnosis and that the effect on cortical thickness was most evident in relation to a measure of maternal binge drinking.

Anterior cingulate cortex surface area relates to behavioral inhibition in adolescents with and without heavy prenatal alcohol exposure

Prenatal alcohol exposure is associated with behavioral disinhibition, yet the brain structure correlates of this deficit have not been determined with sufficient detail. We examined the hypothesis that the structure of the anterior cingulate cortex (ACC) relates to inhibition performance in youth with histories of heavy prenatal alcohol exposure (AE, n = 32) and non-exposed controls (CON, n = 21). Adolescents (12-17 years) underwent structural magnetic resonance imaging yielding measures of gray matter volume, surface area, and thickness across four ACC subregions. A subset of subjects were administered the NEPSY-II Inhibition subtest. MANCOVA was utilized to test for group differences in ACC and inhibition performance and multiple linear regression was used to probe ACC-inhibition relationships. ACC surface area was significantly smaller in AE, though this effect was primarily driven by reduced right caudal ACC (rcACC). AE also performed significantly worse on inhibition speed but not on inhibition accuracy. Regression analyses with the rcACC revealed a significant group × ACC interaction. A smaller rcACC surface area was associated with slower inhibition completion time for AE but was not significantly associated with inhibition in CON. After accounting for processing speed, smaller rcACC surface area was associated with worse (i.e., slower) inhibition regardless of group. Examining processing speed independently, a decrease in rcACC surface area was associated with faster processing speed for CON but not significantly associated with processing speed in AE. Results support the theory that caudal ACC may monitor reaction time in addition to inhibition and highlight the possibility of delayed ACC neurodevelopment in prenatal alcohol exposure.

Mapping the developing human brain in utero using quantitative MR imaging techniques

Magnetic resonance imaging of the human fetal brain has been a clinical tool for many years and provides valuable additional information to compliment more common ultrasound studies. Advances in both MRI acquisition and post processing over the last 10 years have enabled full 3D imaging and the accurate combination of data acquired in different head positions to create improved geometric integrity, tissue contrast, and resolution. This research is now motivating the development of new quantitative MRI-based techniques for clinical imaging that can more accurately characterize brain development and detect abnormalities. In this article, we will review some of the key areas that are driving changes in our understanding of fetal brain growth using quantitative measures derived from in utero MRI and the possible directions for its increased use in improving the evaluation of pregnancies and the accurate characterization of abnormal brain growth.

Fetal alcohol spectrum disorders and cognitive functions of young children

Fetal alcohol spectrum disorder (FASD) is one of the main causes of mental retardation worldwide. Nearly 1% of children in North America are affected from antenatal exposure to ethanol. Its economic burden in industrialized countries is increasing. It is estimated that, in the United States, 4.0 billion dollars are annually expended in the treatment and rehabilitation of these patients. As a pathologic entity, they present with a broad symptomatology. Fetal alcohol syndrome (FAS) is the most readily recognized clinical manifestation of these disorders. Various factors seem to contribute in the pathogenesis of FASD-related cognitive disorders. During the last 20 years, several potential pretranslational and posttranslational factors have been extensively studied in various experimental animal models. Research has specifically focused on several neurotransmitters, insulin resistance, alterations of the hypothalamic-pituitary-adrenal (HPA) axis, abnormal glycosylation of several proteins, oxidative stress, nutritional antioxidants, and various epigenetic factors. The purpose of the present review is to summarize the clinical manifestations of this disorder during childhood and adolescence and to summarize the possible pathophysiologic and epigenetic pathways that have been implicated in the pathophysiology of FASD.