Brain Metabolic Alterations in Adolescents and Young Adults With Fetal Alcohol Spectrum Disorders

Binge-like ethanol exposure during the brain growth spurt disrupts the function of retrosplenial cortex-projecting anterior thalamic neurons in adolescent mice

Ethanol (EtOH) exposure during late pregnancy leads to enduring impairments in learning and memory that may stem from damage to components of the posterior limbic memory system, including the retrosplenial cortex (RSC) and anterior thalamic nuclei (ATN). In rodents, binge-like EtOH exposure during the first week of life (equivalent to the third trimester of human pregnancy) triggers apoptosis in these brain regions. We hypothesized that this effect induces long-lasting alterations in the function of RSC-projecting ATN neurons. To test this hypothesis, vesicular GABA transporter-Venus mice (expressing fluorescently tagged GABAergic interneurons) were subjected to binge-like EtOH vapor exposure on postnatal day (P) 7. This paradigm activated caspase 3 in the anterodorsal (AD), anteroventral (AV), and reticular thalamic nuclei at P7 but did not reduce neuronal density in these areas at P60-70. At P40-60, we injected red retrobeads into the RSC and performed patch-clamp slice electrophysiological recordings from retrogradely labeled neurons in the AD and AV nuclei 3-4 days later. We found significant effects of treatment on instantaneous action potential (AP) frequency and AP overshoot, as well as sex × treatment interactions for AP threshold and overshoot in AD neurons. A sex × treatment interaction was detected for AP number in AV neurons. EtOH exposure also reduced the frequency and amplitude of spontaneous excitatory postsynaptic currents and increased the charge transfer of spontaneous inhibitory postsynaptic currents. These results highlight a novel cellular mechanism that could contribute to the lasting learning and memory deficits associated with developmental EtOH exposure.

Gestational ethanol exposure impairs motor skills in female mice through dysregulated striatal dopamine and acetylcholine function

Fetal alcohol exposure has deleterious consequences on the motor skills of patients affected by Fetal Alcohol Spectrum Disorder (FASD) and in pre-clinical models of gestational ethanol exposure (GEE). Deficits in striatal cholinergic interneurons (CINs) and dopamine function impair action learning and execution, yet the effects of GEE on acetylcholine (ACh) and striatal dopamine release remain unexplored. Here, we report that alcohol exposure during the first ten postnatal days (GEEP0-P10), which mimics ethanol consumption during the last gestational trimester in humans, induces sex-specific anatomical and motor skill deficits in female mice during adulthood. Consistent with these behavioral impairments, we observed increased stimulus evoked-dopamine levels in the dorsolateral striatum (DLS) of GEEP0-P10 female, but not male, mice. Further experiments revealed sex-specific deficits in β2-containing nicotinic ACh receptor (nAChR)-modulation of electrically evoked dopamine release. Moreover, we found a reduced decay of ACh transients and a decreased excitability of striatal CINs in DLS of GEEP0-P10 females, indicating striatal CIN dysfunctions. Finally, the administration of varenicline, a β2-containing nAChR partial agonist, and chemogenetic-mediated increase in CIN activity improved motor performance in adult GEEP0-P10 females. Altogether, these data shed new light on GEE-induced striatal deficits and establish potential pharmacological and circuit-specific interventions to ameliorate motor symptoms of FASD.

Longitudinal Evaluation Using Preclinical 7T-Magnetic Resonance Imaging/Spectroscopy on Prenatally Dose-Dependent Alcohol-Exposed Rats

Prenatal alcohol exposure causes many detrimental alcohol-induced defects in children, collectively known as fetal alcohol spectrum disorders (FASD). This study aimed to evaluate a rat model of FASD, in which alcohol was administered at progressively increasing doses during late pregnancy, using preclinical magnetic resonance (MR) imaging (MRI) and MR spectroscopy (MRS). Wistar rats were orally administered 2.5 mL/day of ethanol (25% concentration) on gestational day 15, and postnatal fetuses were used as FASD models. Four groups were used: a control group (non-treatment group) and three groups of FASD model rats that received one, two, or four doses of ethanol, respectively, during the embryonic period. Body weight was measured every other week until eight weeks of age. MRI and MRS were performed at 4 and 8 weeks of age. The volume of each brain region was measured using acquired T₂-weighted images. At 4 weeks of age, body weight and cortex volume were significantly lower in the three FASD model groups (2.5 × 1: 304 ± 6 mm³, p < 0.05; 2.5 × 2: 302 ± 8 mm³, p < 0.01; 2.5 × 4: 305 ± 6 mm³, p < 0.05) than they were in the non-treatment group (non-treatment: 313 ± 6 mm³). The FASD model group that received four doses of alcohol (2.5 × 4: 0.72 ± 0.09, p < 0.05) had lower Taurine/Cr values than the non-treatment group did (non-treatment: 0.91 ± 0.15), an effect that continued at 8 weeks of age (non-treatment: 0.63 ± 0.09; 2.5 × 4: 0.52 ± 0.09, p < 0.05). This study is the first to assess brain metabolites and volume over time using MRI and MRS. Decreases in brain volume and taurine levels were observed at 4 and 8 weeks of age, suggesting that the effects of alcohol persisted beyond adulthood.

High-resolution imaging in studies of alcohol effect on prenatal development

Fetal alcohol syndrome represents the leading known preventable cause of mental retardation. FAS is on the most severe side of fetal alcohol spectrum disorders that stem from the deleterious effects of prenatal alcohol exposure. Affecting as many as 1 to 5 out of 100 children, FASD most often results in brain abnormalities that extend to structure, function, and cerebral hemodynamics. The present review provides an analysis of high-resolution imaging techniques that are used in animals and human subjects to characterize PAE-driven changes in the developing brain. Variants of magnetic resonance imaging such as magnetic resonance microscopy, magnetic resonance spectroscopy, diffusion tensor imaging, along with positron emission tomography, single-photon emission computed tomography, and photoacoustic imaging, are modalities that are used to study the influence of PAE on brain structure and function. This review briefly describes the aforementioned imaging modalities, the main findings that were obtained using each modality, and touches upon the advantages/disadvantages of each imaging approach.

Combining neuroimaging and behavior to discriminate children with attention deficit-hyperactivity disorder with and without prenatal alcohol exposure

In many patients, ostensible idiopathic attention deficit-hyperactivity disorder (ADHD) may actually stem from covert prenatal alcohol exposure (PAE), a treatment-relevant distinction. This study attempted a receiver-operator characteristic (ROC) classification of children with ADHD into those with PAE (ADHD+PAE) and those without (ADHD-PAE) using neurobehavioral instruments alongside magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) of supraventricular brain white matter. Neurobehavioral, MRS, and DTI endpoints had been suggested by prior findings. Participants included children aged 8-13 years, 23 with ADHD+PAE, 19 with familial ADHD-PAE, and 28 typically developing (TD) controls. With area-under-the-curve (AUC) >0.90, the Conners 3 Parent Rating Scale Inattention (CIn) and Hyperactivity/Impulsivity (CHp) scores and the Behavioral Regulation Index (BRI) of the Behavior Rating Inventory of Executive Function (BRIEF2) excellently distinguished the clinical groups from TD, but not from each other (AUC < 0.70). Combinations of MRS glutamate (Glu) and N-acetyl-compounds (NAA) and DTI mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) yielded "good" (AUC > 0.80) discrimination. Neuroimaging combined with CIn and BRI achieved AUC 0.72 and AUC 0.84, respectively. But neuroimaging combined with CHp yielded 14 excellent combinations with AUC ≥ 0.90 (all p < 0.0005), the best being Glu·AD·RD·CHp/(NAA·FA) (AUC 0.92, sensitivity 1.00, specificity 0.82, p < 0.0005). Using Cho in lieu of Glu yielded AUC 0.83. White-matter microstructure and metabolism may assist efforts to discriminate ADHD etiologies and to detect PAE, beyond the ability of commonly used neurobehavioral measures alone.

Midline Thalamic Damage Associated with Alcohol-Use Disorders: Disruption of Distinct Thalamocortical Pathways and Function

The thalamus, a significant part of the diencephalon, is a symmetrical and bilateral central brain structure. The thalamus is subdivided into three major groups of nuclei based on their function: sensorimotor nuclei (or principal/relay nuclei), limbic nuclei and nuclei bridging these two domains. Anatomically, nuclei within the thalamus are described by their location, such as anterior, medial, lateral, ventral, and posterior. In this review, we summarize the role of medial and midline thalamus in cognition, ranging from learning and memory to flexible adaptation. We focus on the discoveries in animal models of alcohol-related brain damage, which identify the loss of neurons in the medial and midline thalamus as drivers of cognitive dysfunction associated with alcohol use disorders. Models of developmental ethanol exposure and models of adult alcohol-related brain damage and are compared and contrasted, and it was revealed that there are similar (anterior thalamus) and different (intralaminar [adult exposure] versus ventral midline [developmental exposure]) thalamic pathology, as well as disruptions of thalamo-hippocampal and thalamo-cortical circuits. The final part of the review summarizes approaches to recover alcohol-related brain damage and cognitive and behavioral outcomes. These approaches include pharmacological, nutritional and behavioral interventions that demonstrated the potential to mitigate alcohol-related damage. In summary, the medial/midline thalamus is a significant contributor to cognition function, which is also sensitive to alcohol-related brain damage across the life span, and plays a role in alcohol-related cognitive dysfunction.

Neuroimaging of Supraventricular Frontal White Matter in Children with Familial Attention-Deficit Hyperactivity Disorder and Attention-Deficit Hyperactivity Disorder Due to Prenatal Alcohol Exposure

Attention-deficit hyperactivity disorder (ADHD) is common in patients with (ADHD+PAE) and without (ADHD-PAE) prenatal alcohol exposure (PAE). Many patients diagnosed with idiopathic ADHD actually have covert PAE, a treatment-relevant distinction. To improve differential diagnosis, we sought to identify brain differences between ADHD+PAE and ADHD-PAE using neurobehavioral, magnetic resonance spectroscopy, and diffusion tensor imaging metrics that had shown promise in past research. Children 8-13 were recruited in three groups: 23 ADHD+PAE, 19 familial ADHD-PAE, and 28 typically developing controls (TD). Neurobehavioral instruments included the Conners 3 Parent Behavior Rating Scale and the Delis-Kaplan Executive Function System (D-KEFS). Two dimensional magnetic resonance spectroscopic imaging was acquired from supraventricular white matter to measure N-acetylaspartate compounds, glutamate, creatine + phosphocreatine (creatine), and choline-compounds (choline). Whole brain diffusion tensor imaging was acquired and used to to calculate fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity from the same superventricular white matter regions that produced magnetic resonance spectroscopy data. The Conners 3 Parent Hyperactivity/Impulsivity Score, glutamate, mean diffusivity, axial diffusivity, and radial diffusivity were all higher in ADHD+PAE than ADHD-PAE. Glutamate was lower in ADHD-PAE than TD. Within ADHD+PAE, inferior performance on the D-KEFS Tower Test correlated with higher neurometabolite levels. These findings suggest white matter differences between the PAE and familial etiologies of ADHD. Abnormalities detected by magnetic resonance spectroscopy and diffusion tensor imaging co-localize in supraventricular white matter and are relevant to executive function symptoms of ADHD.

Examination of cortically projecting cholinergic neurons following exercise and environmental intervention in a rodent model of fetal alcohol spectrum disorders

BACKGROUND

Up to 1 in 5 infants in the United States are exposed to alcohol prenatally, resulting in neurodevelopmental deficits categorized as fetal alcohol spectrum disorders (FASD). Choline supplementation ameliorates some deficits, suggesting that alcohol exposure (AE) perturbs cholinergic neurotransmission and development. Behavioral interventions, which upregulate cholinergic neurotransmission, rescue cognitive deficits in rodent models of FASD.

METHODS

We investigated the impacts of two interventions (either wheel-running (WR) or "super intervention," WR plus exposure to a complex environment) on cholinergic neuronal morphology in the nucleus basalis of Meynert (NBM), the source of cortical cholinergic input, and prefrontal cortex (PFC) in a rodent model of FASD. One third of the total 47 male pups received intragastric intubation of ethanol in milk substitute during postnatal days (PD) 4-9. Another third served as sham-intubated procedural controls while the final third served as suckle controls. Rats from each group were exposed to either intervention during PD 30-72. Choline acetyltransferase (ChAT⁺ ) and acetylcholinesterase staining were used to quantify cholinergic neuron number, soma volume, and axon number.

RESULTS

Our data indicate a main effect of postnatal treatment on ChAT⁺ neuron number in NBM in adulthood. Post hoc analysis demonstrates that ChAT⁺ neuron number is reduced in AE compared to suckle control rodents (p < .01).

CONCLUSIONS

We examined the cytoarchitectonics of cholinergic neurons in NBM and PFC in adulthood following early postnatal AE and two interventions. We show that AE reduces ChAT⁺ neuron number in NBM, and this is not mitigated by either intervention.

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.

Differential neuroimaging indices in prefrontal white matter in prenatal alcohol-associated ADHD versus idiopathic ADHD

BACKGROUND

Attention deficit-hyperactivity disorder (ADHD) is common in fetal alcohol spectrum disorders (FASD) but also in patients without prenatal alcohol exposure (PAE). Many patients diagnosed with idiopathic ADHD may actually have ADHD and covert PAE, a treatment-relevant distinction.

METHODS

We compared proton magnetic resonance spectroscopic imaging (MRSI; N = 44) and diffusion tensor imaging (DTI; N = 46) of the anterior corona radiata (ACR)-a key fiber tract in models of ADHD-at 1.5 T in children with ADHD with PAE (ADHD+PAE), children with ADHD without PAE (ADHD-PAE), children without ADHD with PAE (non-ADHD+PAE), and children with neither ADHD nor PAE (non-ADHD-PAE, i.e., typically developing controls). Levels of choline-compounds (Cho) were the main MRSI endpoint, given interest in dietary choline for FASD; the main DTI endpoint was fractional anisotropy (FA), as ACR FA may reflect ADHD-relevant executive control functions.

RESULTS

For ACR Cho, there was an ADHD-by-PAE interaction (p = 0.038) whereby ACR Cho was 26.7% lower in ADHD+PAE than in ADHD-PAE children (p < 0.0005), but there was no significant ACR Cho difference between non-ADHD+PAE and non-ADHD-PAE children. Voxelwise false-discovery rate (FDR)-corrected analysis of DTI revealed significantly (q ≤ 0.0101-0.05) lower FA in ACR for subjects with PAE (ADHD+PAE or non-ADHD+PAE) than for subjects without PAE (ADHD-PAE or non-ADHD-PAE). There was no significant effect of ADHD on FA. Thus, in overlapping samples, effects of PAE on Cho and FA were observed in the same white-matter tract.

CONCLUSIONS

These findings point to tract focal, white-matter pathology possibly specific for ADHD+PAE subjects. Low Cho may derive from abnormal choline metabolism; low FA suggests suboptimal white-matter integrity in PAE. More advanced MRSI and DTI-and neurocognitive assessments-may better distinguish ADHD+PAE from ADHD-PAE, helping identify covert cases of FASD.

Functional Connectivity and Metabolic Alterations in Medial Prefrontal Cortex in a Rat Model of Fetal Alcohol Spectrum Disorder: A Resting-State Functional Magnetic Resonance Imaging and in vivo Proton Magnetic Resonance Spectroscopy Study

Prenatal ethanol exposure alters brain structure, functional connectivity, and behavior in humans and rats. Behavioral changes include deficits in executive function, which requires cooperative activity between the frontal cortices and other brain regions. In this study, we analyzed the functional connectivity and neurochemical levels of the prefrontal cortex (PFC) using resting-state functional magnetic resonance imaging (rsfMRI) and proton magnetic resonance spectroscopy (1H-MRS) in ethanol-exposed (Eth) and control (Ctr) rats. Pregnant Long-Evans rats were fed a liquid diet containing ethanol (2.1-6.46% v/v ethanol) from gestational days 6 to 21 (Eth). Ctr animals received an isocaloric, isonutritive liquid diet. In young adulthood, male and female offspring underwent in vivo MRI using a 7.0-Tesla system. 1H-MRS from the PFC and whole brain rsfMRI were obtained on the animals. Seed-based functional connectivity analysis was performed with seeds placed in the PFC, matching the voxel of MRS. Male, but not female, Eth rats showed less functional connectivity between PFC and dorsal striatum than Ctr animals. In Eth males glucose levels were significantly lower, and in Eth females lower levels of phosphorylcholine but an increased gamma-aminobutyric acid/glutamate ratio were observed in the PFC compared with Ctr animals. Prenatal ethanol alters brain metabolism and functional connectivity of the PFC in a sex-dependent manner.

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.

Interhemispheric Functional Brain Connectivity in Neonates with Prenatal Alcohol Exposure: Preliminary Findings

BACKGROUND

Children exposed to alcohol in utero demonstrate reduced white matter microstructural integrity. While early evidence suggests altered functional brain connectivity in the lateralization of motor networks in school-age children with prenatal alcohol exposure (PAE), the specific effects of alcohol exposure on the establishment of intrinsic connectivity in early infancy have not been explored.

METHODS

Sixty subjects received functional imaging at 2 to 4 weeks of age for 6 to 8 minutes during quiet natural sleep. Thirteen alcohol-exposed (PAE) and 14 age-matched control (CTRL) participants with usable data were included in a multivariate model of connectivity between sensorimotor intrinsic functional connectivity networks. Seed-based analyses of group differences in interhemispheric connectivity of intrinsic motor networks were also conducted. The Dubowitz neurological assessment was performed at the imaging visit.

RESULTS

Alcohol exposure was associated with significant increases in connectivity between somatosensory, motor networks, brainstem/thalamic, and striatal intrinsic networks. Reductions in interhemispheric connectivity of motor and somatosensory networks did not reach significance.

CONCLUSIONS

Although results are preliminary, findings suggest PAE may disrupt the temporal coherence in blood oxygenation utilization in intrinsic networks underlying motor performance in newborn infants. Studies that employ longitudinal designs to investigate the effects of in utero alcohol exposure on the evolving resting-state networks will be key in establishing the distribution and timing of connectivity disturbances already described in older children.

Reduced glutamate in white matter of male neonates exposed to alcohol in utero: a (1)H-magnetic resonance spectroscopy study

In utero exposure to alcohol leads to a spectrum of fetal alcohol related disorders (FASD). However, few studies used have used proton magnetic resonance spectroscopy ((1)H-MRS) to understand how neurochemical disturbances relate to the pathophysiology of FASD. Further, no studies to date have assessed brain metabolites in infants exposed to alcohol in utero. We hypothesize that neonates exposed to alcohol in utero will show decreased glutamatergic activity, pre-emptive of their clinical diagnosis or behavioural phenotype. Single voxel (1)H-MRS data, sampled in parietal white and gray matter, were acquired from 36 neonates exposed to alcohol in utero, and 31 control unexposed healthy neonates, in their 2nd-4th week of life. Metabolites relative to creatine with phosophocreatine and metabolites absolute concentrations using a water reference are reported. Male infants exposed to alcohol in utero were found to have reduced concentration of glutamate with glutamine (Glx) in their parietal white matter (PWM), compared to healthy male infants (p = 0.02). Further, male infants exposed to alcohol in utero had reduced concentration and ratio for glutamate (Glu) in their PWM (p = 0.02), compared to healthy male infants and female infants exposed to alcohol in utero. Female infants showed higher relative Glx and Glu ratios for parietal gray matter (PGM, p < 0.01), compared to male infants. We speculate that the decreased Glx and Glu concentrations in PWM are a result of delayed oligodendrocyte maturation, which may be a result of dysfunctional thyroid hormone activity in males exposed to alcohol in utero. Further study is required to elucidate the relationship between Glx and Glu, thyroid hormone activity, and oligodendrocyte maturation in infants exposure to alcohol in utero.

Challenging sleep-wake behaviors reported in informal, conversational interviews of caregivers of children with fetal alcohol spectrum disorder

Objective: Sleep complaints are clinically expected in children exposed to alcohol during pregnancy. We aim to reveal patterns of association among sleep-wake behaviors that are challenging in the life of children with fetal alcohol spectrum disorders (FASD). Methods: Through text-mining analyses, we numericized the transcripts of 59 caregiver's informal, conversational interviews. That is, the relative frequencies-of-occurrences of words as well as their semantic specificities (italic) were clustered, categorized, and visualized for patterns. Results: A total of 4008 words were indexed where sleep took the 91st place of most important words. Sleep and wake were however not associatively conversed throughout the interviews. Sleep-related words conversed were: night, nap, apnea, asleep, awake, bed, bedroom, bedtime, mattress, melatonin, overnight, and wake-up. Among some FASD-characteristic words describing the challenges were: huge, alcohol, manage*, stop, adopt, crazy*. The semantic space reflecting these challenges experienced in caring for children with FASD was divided into two axes: child-oriented vs. other-oriented words, and day-related and night-related words. The position of sleep shows that problematic sleep was expressed as a 'family' issue. Clumsy* was interrelated with problematic sleeping and waking. Despite that mostly night was associatively conversed, the association of Routines, Managing, and Planning with sleep underscores the challenges faced. Conclusion: When conversing caregivers of children with FASD seldom interrelate 'sleep' but rather 'night' with FASD-characteristics. Increased sleep awareness combined with educational initiatives regarding sleep are advocated.

Cortical miscommunication after prenatal exposure to alcohol

We report on the effects of prenatal alcohol exposure on resting-state brain activity as measured by magnetoencephalography (MEG). We studied 37 subjects diagnosed with fetal alcohol spectrum disorder in one of three categories: fetal alcohol syndrome, partial fetal alcohol syndrome, and alcohol-related neurodevelopmental disorder. For each subject, the MEG signal was recorded for 60 s during rest while subjects lay supine. Using time series analysis, we calculated the synchronous neural interactions for all pair-wise combinations of 248 MEG sensors resulting in 30,628 partial correlations for each subject. We found significant differences from control subjects in 6.19 % of the partial zero-lag crosscorrelations (synchronous neural interactions; Georgopoulos et al. in J Neural Eng 4:349-355, 2007), with these differences localized in the right posterior frontal, right parietal, and left parietal/posterior frontal regions. These results show that MEG can detect functional brain differences in the individuals affected by prenatal exposure to alcohol. Furthermore, these differences may serve as a biomarker for future studies linking symptoms and signs to specific brain areas. This may lead to new insights into the neuropathology of fetal alcohol spectrum disorders.

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.

An in vivo 1H magnetic resonance spectroscopy study of the deep cerebellar nuclei in children with fetal alcohol spectrum disorders

BACKGROUND

Prenatal alcohol exposure has been linked to impairment in cerebellar structure and function, including eyeblink conditioning. The deep cerebellar nuclei, which play a critical role in cerebellar-mediated learning, receive extensive inputs from brain stem and cerebellar cortex and provide the point of origin for most of the output fibers to other regions of the brain. We used in vivo (1) H magnetic resonance spectroscopy (MRS) to examine effects of prenatal alcohol exposure on neurochemistry in this important cerebellar region.

METHODS

MRS data from the deep cerebellar nuclei were acquired from 37 children with heavy prenatal alcohol exposure and 17 non- or minimally exposed controls from the Cape Coloured (mixed ancestry) community in Cape Town, South Africa.

RESULTS

Increased maternal alcohol consumption around time of conception was associated with lower N-Acetylaspartate (NAA) levels in the deep nuclei (r = -0.33, p < 0.05). Higher levels of alcohol consumption during pregnancy were related to lower levels of the choline-containing metabolites (r = -0.37, p < 0.01), glycerophosphocholine plus phosphocholine (Cho). Alcohol consumption levels both at conception (r = 0.35, p < 0.01) and during pregnancy (r = 0.38, p < 0.01) were related to higher levels of glutamate plus glutamine (Glx). All these effects continued to be significant after controlling for potential confounders.

CONCLUSIONS

The lower NAA levels seen in relation to prenatal alcohol exposure may reflect impaired neuronal integrity in the deep cerebellar nuclei. Our finding of lower Cho points to disrupted Cho metabolism of membrane phospholipids, reflecting altered neuropil development with potentially reduced content of dendrites and synapses. The alcohol-related alterations in Glx may suggest a disruption of the glutamate-glutamine cycling involved in glutamatergic excitatory neurotransmission.

Longitudinal 1H MRS of rat forebrain from infancy to adulthood reveals adolescence as a distinctive phase of neurometabolite development

This study represents the first longitudinal, within-subject (1) H MRS investigation of the developing rat brain spanning infancy, adolescence and early adulthood. We obtained neurometabolite profiles from a voxel located in a central location of the forebrain, centered on the striatum, with smaller contributions for the cortex, thalamus and hypothalamus, on postnatal days 7, 35 and 60. Water-scaled metabolite signals were corrected for T1 effects and quantified using the automated processing software LCModel, yielding molal concentrations. Our findings indicate age-related concentration changes in N-acetylaspartate + N-acetylaspartylglutamate, myo-inositol, glutamate + glutamine, taurine, creatine + phosphocreatine and glycerophosphocholine + phosphocholine. Using a repeated measures design and analysis, we identified significant neurodevelopment changes across all three developmental ages and identified adolescence as a distinctive phase in normative neurometabolic brain development. Between postnatal days 35 and 60, changes were observed in the concentrations of N-acetylaspartate + N-acetylaspartylglutamate, glutamate + glutamine and glycerophosphocholine + phosphocholine. Our data replicate past studies of early neurometabolite development and, for the first time, link maturational profiles in the same subjects across infancy, adolescence and adulthood.

Neurodevelopmental alcohol exposure elicits long-term changes to gene expression that alter distinct molecular pathways dependent on timing of exposure

BACKGROUND

Maternal alcohol consumption is known to adversely affect fetal neurodevelopment. While it is known that alcohol dose and timing play a role in the cognitive and behavioral changes associated with prenatal alcohol exposure, it is unclear what developmental processes are disrupted that may lead to these phenotypes.

METHODS

Mice (n=6 per treatment per developmental time) were exposed to two acute doses of alcohol (5 g/kg) at neurodevelopmental times representing the human first, second, or third trimester equivalent. Mice were reared to adulthood and changes to their adult brain transcriptome were assessed using expression arrays. These were then categorized based on Gene Ontology annotations, canonical pathway associations, and relationships to interacting molecules.

RESULTS

The results suggest that ethanol disrupts biological processes that are actively occurring at the time of exposure. These include cell proliferation during trimester one, cell migration and differentiation during trimester two, and cellular communication and neurotransmission during trimester three. Further, although ethanol altered a distinct set of genes depending on developmental timing, many of these show interrelatedness and can be associated with one another via 'hub' molecules and pathways such as those related to huntingtin and brain-derived neurotrophic factor.

CONCLUSIONS

These changes to brain gene expression represent a 'molecular footprint' of neurodevelopmental alcohol exposure that is long-lasting and correlates with active processes disrupted at the time of exposure. This study provides further support that there is no neurodevelopmental time when alcohol cannot adversely affect the developing brain.

Molecular and behavioral aspects of the actions of alcohol on the adult and developing brain

The brain is one of the major target organs of alcohol actions. Alcohol abuse can lead to alterations in brain structure and functions and, in some cases, to neurodegeneration. Cognitive deficits and alcohol dependence are highly damaging consequences of alcohol abuse. Clinical and experimental studies have demonstrated that the developing brain is particularly vulnerable to alcohol, and that drinking during gestation can lead to a range of physical, learning and behavioral defects (fetal alcohol spectrum disorders), with the most dramatic presentation corresponding to fetal alcohol syndrome. Recent findings also indicate that adolescence is a stage of brain maturation and that heavy drinking at this stage can have a negative impact on brain structure and functions causing important short- and long-term cognitive and behavioral consequences. The effects of alcohol on the brain are not uniform; some brain areas or cell populations are more vulnerable than others. The prefrontal cortex, the hippocampus, the cerebellum, the white matter and glial cells are particularly susceptible to the effects of ethanol. The molecular actions of alcohol on the brain are complex and involve numerous mechanisms and signaling pathways. Some of the mechanisms involved are common for the adult brain and for the developing brain, while others depend on the developmental stage. During brain ontogeny, alcohol causes irreversible alterations to the brain structure. It also impairs several molecular, neurochemical and cellular events taking place during normal brain development, including alterations in both gene expression regulation and the molecules involved in cell-cell interactions, interference with the mitogenic and growth factor response, enhancement of free radical formation and derangements of glial cell functions. However, in both adult and adolescent brains, alcohol damages specific brain areas through mechanisms involving excitotoxicity, free radical formation and neuroinflammatory damage resulting from activation of the innate immune system mediated by TLR4 receptors. Alcohol also acts on specific membrane proteins, such as neurotransmitter receptors (e.g. NMDA, GABA-A), ion channels (e.g. L-type Ca²⁺ channels, GIRKs), and signaling pathways (e.g. PKA and PKC signaling). These effects might underlie the wide variety of behavioral effects induced by ethanol drinking. The neuroadaptive changes affecting neurotransmission systems which are more sensitive to the acute effects of alcohol occur after long-term alcohol consumption. Alcohol-induced maladaptations in the dopaminergic mesolimbic system, abnormal plastic changes in the reward-related brain areas and genetic and epigenetic factors may all contribute to alcohol reinforcement and alcohol addiction. This manuscript reviews the mechanisms by which ethanol impacts the adult and the developing brain, and causes both neural impairments and cognitive and behavioral dysfunctions. The identification and the understanding of the cellular and molecular mechanisms involved in ethanol toxicity might contribute to the development of treatments and/or therapeutic agents that could reduce or eliminate the deleterious effects of alcohol on the brain.

Developmental cortical thinning in fetal alcohol spectrum disorders

Regional cortical thickness was evaluated using CIVET processing of 3D T1-weighted images (i) to compare the variation in cortical thickness between 33 participants with fetal alcohol spectrum disorders (FASD) aged 6-30 years (mean age 12.3 years) versus 33 age/sex/hand-matched controls, and (ii) to examine developmental changes in cortical thickness with age from children to young adults in both groups. Significant cortical thinning was found in the participants with FASD in large areas of the bilateral middle frontal lobe, pre- and post- central areas, lateral and inferior temporal and occipital lobes compared to controls. No significant cortical thickness increases were observed for the FASD group. Cortical thinning with age in a linear model was observed in both groups, but the locations were different for each group. FASD participants showed thinning with age in the left middle frontal, bilateral precentral, bilateral precuneus and paracingulate, left inferior occipital and bilateral fusiform gyri; while controls showed decreases with age in the bilateral middle frontal gyrus, right inferior frontal gyrus, bilateral precuneus gyrus, and bilateral occipital gyrus. A battery of cognitive assessments of memory, attention, motor, and verbal abilities was conducted with many of the FASD participants, but no significant correlations were found between these cognitive scores and regional cortical thickness. Non-invasive measurements of cortical thickness in children to young adults with FASD have identified both key regions of cortex that may be more deleteriously affected by prenatal alcohol exposure as well as cortical changes with age that differ from normal developmental thinning.

Sleep and sensory characteristics in young children with fetal alcohol spectrum disorder

BACKGROUND

: Fetal alcohol spectrum disorder (FASD) is a syndrome that results from prenatal alcohol exposure and is defined by significant neurobehavioral impairments. Sleep disruption has been recognized as a clinically important symptom of FASD that has multiple negative effects on the child's health, ability to function adaptively, as well as on family and caregivers. However, few studies have addressed and characterized the sleep problems in this population.

OBJECTIVE

: The objective of this study was to characterize sleep in FASD and describe the impact of sensory processing difficulties on sleep patterns in children with FASD.

METHODS

: Children with FASD were compared with age-matched typically developing children between 3 and 6 years of age. Sleep was assessed using actigraphy, a sleep log, and the Children's Sleep Habits Questionnaire. The Sensory Profile™, completed by caregivers, was used to evaluate the child's sensory processing abilities. Overall differences in sensory processing were correlated with actigraphic parameters measured in alcohol exposed and control groups.

RESULTS

: Data show that children with FASD have significantly more sleep disturbances than typically developing children, including increased bedtime resistance, shortened sleep duration, increased sleep anxiety, and increased night awakenings and parasomnias. Actigraphy reveals a significant difference between groups for sleep onset latency.

CONCLUSIONS

: This study demonstrates that sensory processing deficits are widespread in children with FASD and that these deficits are associated with multiple sleep problems. Children with FASD should be screened for sleep-related disorders and would benefit from occupational therapy for sensory-based treatment aimed at sleep regulation and consolidation.

Extensive deep gray matter volume reductions in children and adolescents with fetal alcohol spectrum disorders

BACKGROUND

The link between the numerous cognitive, motor, and behavioral difficulties of individuals with fetal alcohol spectrum disorders (FASD) and underlying specific structural brain injuries can be investigated using high-resolution imaging. Differential sensitivity of the brain's "relay" stations, namely the deep gray matter structures, may play a key factor given their multifaceted role in brain function. The purpose of our study was to analyze differences in deep gray matter volumes of children and adolescents with FASD relative to age/sex-matched controls and to examine whether any volume differences were consistent across the age range of neurodevelopment.

METHODS

Children and adolescents (N = 28, 6 to 17 years) diagnosed with FASD and 56 age- and sex-matched healthy controls (i.e., 2 matched controls per FASD subject) underwent 3-dimensional T1-weighted MRI scans that were used for the automated volume measurement (FreeSurfer) of the intracranial space, total white matter, cortical gray matter, and 6 deep gray matter structures, namely the hippocampus, amygdala, thalamus, caudate, putamen, and globus pallidus, with left and right measured separately. Volumes were compared between FASD and controls, as well as changes with age.

RESULTS

Significant reductions of volume in FASD were observed for the intracranial vault (7.6%), total white matter (8.6%), total cortical gray matter (7.8%), and total deep gray matter (13.1%). All 6 deep gray matter structures showed significant volume reductions bilaterally with the caudate (approximately 16%) and globus pallidus (approximately 18%) being most affected. The hippocampus, thalamus, and globus pallidus showed reductions in all 3 age subgroups (6 to 9, 10 to 13, and 14 to 17 years) but the caudate and putamen had smaller volumes for FASD only within the 2 youngest subgroups; the amygdala was only smaller for FASD in the 2 oldest subgroups.

CONCLUSIONS

Significant, but variable, volume reductions throughout the deep gray matter are observed over a wide age range of 6 to 17 years in FASD.

Goal-directed arm movements in children with fetal alcohol syndrome: a kinematic approach

BACKGROUND

Although many studies have documented deficits in general motor functioning in children with fetal alcohol syndrome (FAS), few have employed detailed measurements to explore the specific nature of such disabilities. This pilot study explores whether three-dimensional (3D) kinematic analysis may generate increased knowledge of the effect of intrauterine alcohol exposure on motor control processes by detecting atypical upper-limb movement pattern specificity in children with FAS relative to typically developing (TD) children.

METHODS

Left and right arm and head movements during a sequential unimanual goal-directed precision task in a sample of children with FAS and in TD children were registered by an optoelectronic tracking system (ProReflex, Qualisys Inc.).

RESULTS

Children with FAS demonstrated evidently poorer task performance compared with TD children. Additionally, analyses of arm movement kinematics revealed atypical spatio-temporal organization in the children with FAS. In general, they exhibited longer arm movement trajectories at both the proximal and distal level, faster velocities at the proximal level but slower at the distal level, and more segmented distal movements. Children with FAS also showed atypically augmented and fast head movements during the task performance.

CONCLUSIONS

Findings indicate neuromotor deficits and developmental delay in goal-directed arm movements because of prenatal alcohol exposure. It is suggested that 3D kinematic analysis is a valid technique for furthering the understanding of motor control processes in children with FAS/fetal alcohol spectrum disorders. A combination with relevant neuroimaging techniques in future studies would enable a more clear-cut interpretation of how atypical movement patterns relate to underlying brain abnormalities.

Magnetic resonance-based imaging in animal models of fetal alcohol spectrum disorder

Magnetic resonance imaging (MRI) techniques, such as magnetic resonance microscopy (MRM), diffusion tensor imaging (DTI), and magnetic resonance spectroscopy (MRS), have recently been applied to the study of both normal and abnormal structure and neurochemistry in small animals. Herein, findings from studies in which these methods have been used for the examination of animal models of Fetal Alcohol Spectrum Disorder (FASD) are discussed. Emphasis is placed on results of imaging studies in fetal and postnatal mice that have highlighted the developmental stage dependency of prenatal ethanol exposure-induced CNS defects. Consideration is also given to the promise of methodological advances to allow in vivo studies of aberrant brain and behavior relationships in model animals and to the translational nature of this work.

Regional brain volume reductions relate to facial dysmorphology and neurocognitive function in fetal alcohol spectrum disorders

Individuals with heavy prenatal alcohol exposure can experience significant deficits in cognitive and psychosocial functioning and alterations in brain structure that persist into adulthood. In this report, data from 99 participants collected across three sites (Los Angeles and San Diego, California, and Cape Town, South Africa) were analyzed to examine relationships between brain structure, neurocognitive function, facial morphology, and maternal reports of quantities of alcohol consumption during the first trimester. Across study sites, we found highly significant volume reductions in the FASD group for all of the brain regions evaluated. After correcting for scan location, age, and total brain volume, these differences remained significant in some regions of the basal ganglia and diencephalon. In alcohol-exposed subjects, we found that smaller palpebral fissures were significantly associated with reduced volumes in the ventral diencephalon bilaterally, that greater dysmorphology of the philtrum predicted smaller volumes in basal ganglia and diencephalic structures, and that lower IQ scores were associated with both smaller basal ganglia volumes and greater facial dysmorphology. In subjects from South Africa, we found a significant negative correlation between intracranial volume and total number of drinks per week in the first trimester. These results corroborate previous reports that prenatal alcohol exposure is particularly toxic to basal ganglia and diencephalic structures. We extend previous findings by illustrating relationships between specific measures of facial dysmorphology and the volumes of particular subcortical structures, and for the first time show that continuous measures of maternal alcohol consumption during the first trimester relates to overall brain volume reduction.

Cognitive and behavioral effects of prenatal alcohol exposure

Children exposed to substantial amounts of alcohol prenatally are known to display a range of physical and cognitive anomalies, referred to as fetal alcohol spectrum disorders (FASDs). Animal models and neuroimaging studies of FASDs have consistently demonstrated that specific regions of the brain (e.g., midline structures) are more vulnerable to the teratogenic effects of alcohol than other regions. The main aim of this article is to assess whether findings from cognitive–behavioral studies of FASDs yield a profile that maps onto the pattern of damage revealed by neuroanatomical investigations. To achieve this aim, the findings from studies that have investigated elementary functions (e.g., associative learning), general functions (e.g., intellectual abilities), specific functions (e.g., language and memory) and behavior in children and adults with FASDs are examined. The cognitive–behavioral profile emerging from the data is defined as a generalized deficit in processing and integrating complex information. It is proposed that slow processing of information mainly contributes to this deficit. The clinical implications of the above characterization of the cognitive–behavioral profile in FASDs are discussed.

Fetal alcohol spectrum disorders: gene-environment interactions, predictive biomarkers, and the relationship between structural alterations in the brain and functional outcomes

Prenatal alcohol exposure is a major, preventable cause of behavioral and cognitive deficits in children. Despite extensive research, a unique neurobehavioral profile for children affected by prenatal alcohol exposure remains elusive. A fundamental question that must be addressed is how genetic and environmental factors interact with gestational alcohol exposure to produce neurobehavioral and neurobiological deficits in children. The core objectives of the NeuroDevNet team in fetal alcohol spectrum disorders is to create an integrated research program of basic and clinical investigations that will (1) identify genetic and epigenetic modifications that may be predictive of the neurobehavioral and neurobiological dysfunctions in offspring induced by gestational alcohol exposure and (2) determine the relationship between structural alterations in the brain induced by gestational alcohol exposure and functional outcomes in offspring. The overarching hypothesis to be tested is that neurobehavioral and neurobiological dysfunctions induced by gestational alcohol exposure are correlated with the genetic background of the affected child and/or epigenetic modifications in gene expression. The identification of genetic and/or epigenetic markers that are predictive of the severity of behavioral and cognitive deficits in children affected by gestational alcohol exposure will have a profound impact on our ability to identify children at risk.

Structural, metabolic, and functional brain abnormalities as a result of prenatal exposure to drugs of abuse: evidence from neuroimaging

Prenatal exposure to alcohol and stimulants negatively affects the developing trajectory of the central nervous system in many ways. Recent advances in neuroimaging methods have allowed researchers to study the structural, metabolic, and functional abnormalities resulting from prenatal exposure to drugs of abuse in living human subjects. Here we review the neuroimaging literature of prenatal exposure to alcohol, cocaine, and methamphetamine. Neuroimaging studies of prenatal alcohol exposure have reported differences in the structure and metabolism of many brain systems, including in frontal, parietal, and temporal regions, in the cerebellum and basal ganglia, as well as in the white matter tracts that connect these brain regions. Functional imaging studies have identified significant differences in brain activation related to various cognitive domains as a result of prenatal alcohol exposure. The published literature of prenatal exposure to cocaine and methamphetamine is much smaller, but evidence is beginning to emerge suggesting that exposure to stimulant drugs in utero may be particularly toxic to dopamine-rich basal ganglia regions. Although the interpretation of such findings is somewhat limited by the problem of polysubstance abuse and by the difficulty of obtaining precise exposure histories in retrospective studies, such investigations provide important insights into the effects of drugs of abuse on the structure, function, and metabolism of the developing human brain. These insights may ultimately help clinicians develop better diagnostic tools and devise appropriate therapeutic interventions to improve the condition of children with prenatal exposure to drugs of abuse.

Fetal brain during a binge drinking episode: a dynamic susceptibility contrast MRI fetal brain perfusion study

We assessed the effects of a single episode of maternal alcohol intoxication on fetal brain blood perfusion in three pregnant dams (baboons) at the 24th week of pregnancy using dynamic susceptibility contrast magnetic resonance imaging. After the oral administration of alcohol, there was a four-fold increase in the peak contrast concentrations in the fetal brain. In addition, we observed a two- to three-fold increase in the contrast uptake and washout rates in the fetal brain. The underlying mechanisms of these changes are unknown, but we hypothesized that these could include the alcohol-mediated changes in placental permeability and fetal cerebral blood flow. Our findings indicate that alcohol intoxication produces profound changes, which may detrimentally influence neurodevelopmental processes in the brain.

Cingulate gyrus morphology in children and adolescents with fetal alcohol spectrum disorders

Alcohol consumption during pregnancy can lead to a variety of cognitive and other birth defects, collectively termed fetal alcohol spectrum disorders (FASD), and including the Fetal Alcohol Syndrome (FAS). This study examined the impact of gestational alcohol exposure on the morphology of the cingulate gyrus, given this region's role in cognitive control, attention, and emotional regulation, all of which are affected in children with FASD. Thirty-one youth (ages 8-16) with histories of heavy prenatal alcohol exposure (n=21) and demographically matched comparison subjects (n=10) underwent structural magnetic resonance imaging. The cingulate gyrus was manually delineated, and parcellated volumes of grey and white matter were compared across groups. Alcohol-exposed individuals had significantly smaller raw cingulate grey matter, white matter, and tissue volumes compared with controls. After adjustment for respective cranial tissue constituents, only white matter volumes remained significantly reduced, and this held regardless of whether or not the child qualified for a diagnosis of FAS. A correlation between posterior cingulate grey matter volume and the WISC-III Freedom from Distractibility Index was also observed in alcohol-exposed children. These data suggest that cingulate white matter is compromised beyond global white matter hypoplasia in alcohol-exposed individuals, regardless of FAS diagnosis. The observed volumetric reductions in the cingulate gyrus may contribute to the disruptive and emotionally dysregulated behavioral profile commonly observed in this population.

Atypical functional lateralization in children with fetal alcohol syndrome

In order to explore effects of prenatal alcohol exposure on functional lateralization, item tasks measuring preferences of hand, foot, eye, and ear were administered to a sample of 23 children diagnosed with fetal alcohol syndrome (FAS) compared with typically developing (TD) children. In addition, a dichotic listening task was administered to a subsample of 11 children with FAS and a TD group of comparable age, sex and handedness. The children with FAS were characterized by increased nonright-handedness compared with TD children. No differences were evident for preferential use of foot, eye, or ear. Moreover, children with FAS displayed more right ear extinctions during dichotic listening relative to TD children, indicating a lack of right ear advantage. The results add to findings of decreased manual asymmetry and less left-lateralized speech perception in children with developmental disorders, and are further discussed in relation to the high incidence of callosal abnormalities in alcohol-exposed children.

BOLD response during spatial working memory in youth with heavy prenatal alcohol exposure

BACKGROUND

Prenatal alcohol exposure has been consistently linked to neurocognitive deficits and structural brain abnormalities in affected individuals. Structural brain abnormalities observed in regions supporting spatial working memory (SWM) may contribute to observed deficits in visuospatial functioning in youth with fetal alcohol spectrum disorders (FASDs).

METHODS

We used functional magnetic resonance imaging (fMRI) to assess the blood oxygen level dependent (BOLD) response in alcohol-exposed individuals during a SWM task. There were 22 young subjects (aged 10-18 years) with documented histories of heavy prenatal alcohol exposure (ALC, n = 10), and age- and sex-matched controls (CON, n = 12). Subjects performed a SWM task during fMRI that alternated between 2-back location matching (SWM) and simple attention (vigilance) conditions.

RESULTS

Groups did not differ on task accuracy or reaction time to the SWM condition, although CON subjects had faster reaction times during the vigilance condition (617 millisecond vs. 684 millisecond, p = 0.03). Both groups showed similar overall patterns of activation to the SWM condition in expected regions encompassing bilateral dorsolateral prefrontal lobes and parietal areas. However, ALC subjects showed greater BOLD response to the demands of the SWM relative to the vigilance condition in frontal, insular, superior, and middle temporal, occipital, and subcortical regions. CON youth evidenced less increased brain activation to the SWM relative to the vigilance task in these areas (p < 0.05, clusters > 1,664 microl). These differences remained significant after including Full Scale IQ as a covariate. Similar qualitative results were obtained after subjects taking stimulant medication were excluded from the analysis.

CONCLUSIONS

In the context of equivalent performance to a SWM task, the current results suggest that widespread increases in BOLD response in youth with FASDs could either indicate decreased efficiency of relevant brain networks, or serve as a compensatory mechanism for deficiency at neural and/or cognitive levels. In context of existing fMRI evidence of heightened prefrontal activation in response to verbal working memory and inhibition demands, the present findings may indicate that frontal structures are taxed to a greater degree during cognitive demands in individuals with FASDs.

Altered neurometabolites and motor integration in children exposed to methamphetamine in utero

Methamphetamine (METH) is a neurotoxic drug. This study aimed to evaluate brain metabolite levels and cognitive function in young children with prenatal METH exposure. 101 children ages 3-4 years were evaluated with neuropsychological tests and underwent proton magnetic resonance spectroscopy ((1)H-MRS) without sedation. Complete datasets from 49 METH-exposed and 49 controls who completed the neuropsychological test battery, and 38 METH-exposed and 37 controls with high-quality MR spectra are reported here. Despite similar physical characteristics (including head circumference), global cognitive function (on Stanford-Binet), parental education, intelligence, mood, and socioeconomic status, METH-exposed children had higher total creatine (tCr: +7%, p=0.003), N-acetyl compounds (NA: +4.3%, p=0.004) and glutamate+glutamine (GLX: +9.6%, p=0.02) concentrations in the frontal white matter, but lower myoinositol (MI: -7%, p=0.01) and MI/tCr (-7.5%, p=0.03) in the thalamus, than control children. The higher frontal white matter NA in the METH-exposed children was due to the higher NA in the METH-exposed girls (+10.2%, p=0.003), but not the boys (+0.8%) compared to sex-matched controls. Furthermore, the METH-exposed children had poorer performance on a visual motor integration (VMI) task, which correlated with lower MI in the thalamus (r=0.26, p=0.03). The higher NA, tCr and GLX concentrations suggest higher neuronal density or cellular compactness in the white matter, especially in the girls, whereas the lower MI suggests lower glial content in the thalamus of these METH-expose children. These findings combined with their poorer performance on VMI also suggest accelerated but aberrant neuronal and glial development in these brain regions.

LCHD, Domingues RC, Brito AR, Werner Jr. J, Herdy GVH. Proton magnetic resonance spectroscopy in children with fetal alcohol spectrum disorders

OBJECTIVE: To analyze the metabolic constitution of brain areas through proton magnetic resonance spectroscopy in children affected with fetal alcohol spectrum disorder compared with normal children. METHOD: The sample of this case-control study included eight boys with epidemiologic history of in utero exposure to alcohol (median age 13.6±3.8 years) who were diagnosed with fetal alcohol spectrum disorder, and eight controls (median age 12.1±3,4 years). An 8 cm³ single voxel approach was used, with echo time 30 ms, repetition time 1500 ms, and 128 acquisitions in a 1.5T scanner, and four brain areas were analyzed: anterior cingulate, left frontal lobe, left striatum, and left cerebellar hemisphere. Peaks and ratios of metabolites N-acetylaspartate, choline, creatine, and myo-inositol were measured. RESULTS: Children with fetal alcohol spectrum disorder showed a decrease in choline/creatine ratio (p=0.020) in left striatum and an increase in myo-inositol/creatine ratio (p=0.048) in left cerebellum compared with controls. There was no statistically significant difference in all peaks and ratios from the anterior cingulate and frontal lobe between the two groups. CONCLUSION: This study found evidence that the left striatum and left cerebellum are affected by intrauterine exposure to alcohol. Additional studies with larger samples are necessary to expand our knowledge of the effects of fetal exposure to alcohol.

Magnetic resonance spectroscopy outcomes from a comprehensive magnetic resonance study of children with fetal alcohol spectrum disorders

Magnetic resonance (MR) technology offers noninvasive methods for in vivo assessment of neuroabnormalities. A comprehensive neuropsychological/behavioral, MR imaging (MRI), MR spectroscopy (MRS) and functional MRI (fMRI) assessment was administered to children with fetal alcohol spectrum disorders (FASD) to determine whether global and/or focal abnormalities could be identified and to distinguish diagnostic subclassifications across the spectrum. The four study groups included (1) FAS/partial FAS; (2) static encephalopathy/alcohol exposed (SE/AE); (3) neurobehavioral disorder/alcohol exposed (ND/AE) as diagnosed with the FASD 4-Digit Code; and (4) healthy peers with no prenatal alcohol exposure. Results are presented in four separate reports: MRS (reported here) and neuropsychological/behavioral, MRI and fMRI outcomes (reported separately). MRS was used to compare neurometabolite concentrations [choline (Cho), n-acetyl-aspartate (NAA) and creatine (Cre)] in a white matter region and a hippocampal region between the four study groups. Choline concentration in the frontal/parietal white matter region, lateral to the midsection of the corpus callosum, was significantly lower in FAS/PFAS relative to all other study groups. Choline decreased significantly with decreasing frontal white matter volume and corpus callosum length. These outcomes suggest low choline concentrations may reflect white matter deficits among FAS/PFAS. Choline also decreased significantly with increasing severity of the 4-Digit FAS facial phenotype, increasing impairment in psychological performance and increasing alcohol exposure. NAA and Cre concentrations did not vary significantly. This study provides further evidence of the vulnerability of the cholinergic system in FASD.

Foetal Alcohol Spectrum Disorders and alterations in brain and behaviour

The term 'Foetal Alcohol Spectrum Disorders (FASD)' refers to the range of disabilities that may result from prenatal alcohol exposure. This article reviews the effects of ethanol on the developing brain and its long-term structural and neurobehavioural consequences. Brain imaging, neurobehavioural and experimental studies demonstrate the devastating consequences of prenatal alcohol exposure on the developing central nervous system (CNS), identifying specific brain regions affected, the range of severity of effects and mechanisms involved. In particular, neuroimaging studies have demonstrated overall and regional volumetric and surface area reductions, abnormalities in the shape of particular brain regions, and reduced and increased densities for white and grey matter, respectively. Neurobehaviourally, FASD consists of a continuum of long-lasting deficits affecting multiple aspects of cognition and behaviour. Experimental studies have also provided evidence of the vulnerability of the CNS to the teratogenic effects of ethanol and have provided new insight on the influence of risk factors in the type and severity of observed brain abnormalities. Finally, the potential molecular mechanisms that underlie the neuroteratological effects of alcohol are discussed, with particular emphasis on the role of glial cells in long-term neurodevelopmental liabilities.

Neuroimaging and fetal alcohol spectrum disorders

The detrimental effects of prenatal alcohol exposure on the developing brain include structural brain anomalies as well as cognitive and behavioral deficits. Initial neuroimaging studies of fetal alcohol spectrum disorders (FASD) using magnetic resonance imaging (MRI) confirmed previous autopsy reports of overall reduction in brain volume and central nervous system (CNS) disorganization, with specific structural abnormalities of the corpus callosum, cerebellum, caudate, and hippocampus. Advances in neuroimaging techniques have allowed detection of regional increases in cortical thickness and gray matter volume along with decreased volume and disorganization of white matter in individuals with FASD. In addition, functional imaging studies have found functional and neurochemical differences in those prenatally exposed to alcohol. Behavioral alterations noted in individuals with FASD are consistent with the findings noted in the brain imaging studies. Continued neuroimaging studies are needed to further advance understanding of the neuroteratogenic effects of alcohol.

Characterization of white matter microstructure in fetal alcohol spectrum disorders

BACKGROUND

Exposure to alcohol during gestation is associated with CNS alterations, cognitive deficits, and behavior problems. This study investigated microstructural aspects of putative white matter abnormalities following prenatal alcohol exposure.

METHODS

Diffusion tensor imaging was used to assess white matter microstructure in 27 youth (age range: 8 to 18 years) with (n = 15) and without (n = 12) histories of heavy prenatal alcohol exposure. Voxelwise analyses, corrected for multiple comparisons, compared fractional anisotropy (FA) and mean diffusivity (MD) between groups, throughout the cerebrum.

RESULTS

Prenatal alcohol exposure was associated with low FA in multiple cerebral areas, including the body of the corpus callosum and white matter innervating bilateral medial frontal and occipital lobes. Fewer between-group differences in MD were observed.

CONCLUSIONS

These data provide an account of cerebral white matter microstructural integrity in fetal alcohol spectrum disorders and support extant literature showing that white matter is a target of alcohol teratogenesis. The white matter anomalies characterized in this study may relate to the neurobehavioral sequelae associated with gestational alcohol exposure, especially in areas of executive dysfunction and visual processing deficits.

Brain diffusion abnormalities in children with fetal alcohol spectrum disorder

BACKGROUND

Children with fetal alcohol spectrum disorder (FASD) have a variety of cognitive, behavioral, and neurological impairments, including structural brain damage. Despite the importance of white matter connections for proper brain function, little is known about how these connections, and the deep gray matter structures that act as relay stations, are affected in children with FASD. The purpose of this study was to use diffusion tensor imaging, an advanced magnetic resonance imaging technique, to examine microstructural differences of white and deep gray matter in children with FASD.

METHODS

Subjects were 24 children aged 5-13 years previously diagnosed with FASD and 95 healthy children over the same age range. Diffusion tractography was used to delineate 10 major white matter tracts in each individual, and region-of-interest analysis was used to assess 4 deep gray matter structures. Fractional anisotropy, an indicator of white matter integrity, and mean diffusivity, a measure of the average water diffusion, were assessed in all 14 brain structures.

RESULTS

Diffusion tensor imaging revealed significant differences of diffusion parameters in several areas of the brain, including the genu and splenium of the corpus callosum, cingulum, corticospinal tracts, inferior fronto-occipital fasciculus, inferior and superior longitudinal fasciculi, globus pallidus, putamen, and thalamus. Reduced white and gray matter volumes, as well as total brain volume, were observed in the FASD group.

CONCLUSIONS

These results demonstrate diffusion abnormalities in FASD beyond the corpus callosum and suggest that several specific white matter regions, particularly commissural and temporal connections, and deep gray matter areas of the brain are sensitive to prenatal alcohol exposure.

Neonatal alcohol-induced region-dependent changes in rat brain neurochemistry measured by high-resolution magnetic resonance spectroscopy

BACKGROUND

Maternal drinking during pregnancy can lead to a range of deleterious outcomes in the developing offspring that have been collectively termed fetal alcohol spectrum disorders (FASDs). There is interest and recognized value in using non-invasive neuroimaging techniques such as magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to characterize, respectively, structural and biochemical alterations in individuals with FASDs. To date, however, results with MRS have been inconsistent regarding the degree and/or nature of abnormalities.

METHODS

High-resolution magic angle spinning (HR-MAS) proton ((1)H) MRS is an ex vivo neuroimaging technique that can acquire spectra in small punches of intact tissue, providing clinically relevant neurochemical information about discrete brain regions. In this study, HR-MAS (1)H MRS was used to examine regional neurochemistry in frontal cortex, striatum, hippocampus, and cerebellum of young rats previously exposed to ethanol as neonates. Key neurochemicals of interest included N-acetyl-aspartate (NAA), glutamate, GABA, glutamine, creatine, choline and myo-inositol.

RESULTS

Daily neonatal alcohol exposure from postnatal day 4 (PN4) through PN9 significantly reduced levels of NAA and taurine in the cerebellum and striatum, and induced sex-dependent reductions in cerebellar glutamate when measured on PN16. In addition, myo-inositol was significantly increased in cerebellum. The frontal cortex and hippocampus were virtually unaffected by this neonatal alcohol exposure.

CONCLUSION

Results of this research may have implications for understanding the underlying neurobiology associated with FASDs and aid in testing treatments in the future. Ongoing studies are assessing the developmental persistence of and/or maturational recovery from these changes.

Challenges of diagnosis in fetal alcohol syndrome and fetal alcohol spectrum disorder in the adult

Adults with fetal alcohol syndrome (FAS) and the subsets of individuals with attenuated phenotype subsumed under the umbrella term of fetal alcohol spectrum disorder (FASD) provide clinicians with a challenge. Compounding this, FASD is different from most genetic syndromes since a specific diagnostic biological test is not available. The diagnosis first needs to be suspected and confirmation requires a diagnostic assessment that is best carried out in the context of a multi-disciplinary team approach. There is surprisingly little research published on the prevalence, natural history, medical, and social complications relevant to adults with FASD. The evidence that is emerging suggests that this disorder is common, and that services to diagnose and treat these individuals are limited. Adults with FASD have a higher incidence of impairments in social adaptive and executive function, and a higher degree of psychopathology when compared to the general population. The impact of FASD has significant and serious effects on those affected with FASD, their families, and our communities. There is a need for improved access to diagnosis, and more research and evaluation of interventions currently in use. In this paper, we describe the current diagnostic criteria, the differential diagnosis, the prevalence, natural history, the behavioral and mental health consequences, medical and social management issues, and interventions for adults affected with this disorder.