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. (C) 2017 Elsevier Inc. All rights reserved

Cerebral intraventricular hemorrhage and post-hemorrhagic ventricular dilatation in preterm infants: new mechanistic insights and potential treatment strategies

Intraventricular hemorrhage (IVH) is one of the major co-morbidities of premature birth associated with post-hemorrhagic ventricular dilatation (PHVD) development, long-term neurodevelopmental impairment, behavioral problems, special educational needs, and dependency on social security.Hypothesis and aims: We believe that extravasated blood and further release of extracellular hemoglobin (Hb) are crucial in brain injury following IVH and consequent development of PHVD. The overall goal of this project focuses on further pathogenetic insights of white and gray matter (GM) injury following IVH and the development of possible neuroprotective treatment strategies that may promote brain development in preterm infants.Methods: Paper I. We characterized extracellular Hb distribution within preriventricular white matter (WM) in preterm rabbit pups following IVH. Paper II. We evaluated the cerebral biodistribution and possible functional neuroprotection of intracerebroventricularly administered alpha-1-microglobulin (A1M), a heme and free radical scavenger, in preterm rabbit pups following IVH. Paper III. We conducted a comprehensive review of preclinical and clinical studies on WM injury following IVH. Paper IV. We evaluated high-frequency ultrasound (HFU) as a tool for the reconstruction of volumetric volume in preterm rabbit pups with PHVD and compared its accuracy and reliability with that of a gold-standard – magnetic resonance imaging (MRI). Paper V. We established a novel model of PHVD in preterm rabbit pups and characterized the survival, neurobehavior, WM, and GM injury, as well as altered corticogenesis.Results: Paper I. Following IVH extracellular Hb was widely distributed throughout the brain WM, particularly in periventricular white matter areas with high extracellular plasticity following IVH. Paper II. Exogenous A1M (recombinant) was extensively distributed within brain WM with further extension into cerebellar WM following IVH. Moreover, A1M exhibited high co-existence with extracellular Hb. Administration of A1M (human) decreased pro-inflammatory and oxidative damage. Paper III. A wide range of animal models have been used to explore pathogenetic mechanisms of IVH and related brain damage; possible targets involved in enhancing brain damage have been identified. Nevertheless, the effectiveness of potential interventions is still limited. Paper IV. HFU-based volumetric reconstruction of brain ventricles is highly accurate and reliable as compared to MRI and may be a promising bed-side tool for evaluating of progression of PHVD in preterm infants. Paper V. IVH and PHVD lead to a long-term alteration of cortical myelination microstructure, disruption of cortical organization, selectively reduction in neurogenesis and synaptogenesis, reduction in parvalbumin-positive interneurons and their dysmaturation.Conclusions: Extracellular Hb travels easily throughout brain WM following IVH and it may be one of the key factors for induction of brain damage by triggering pro-inflammatory and oxidative cascades. Furthermore, IVH, leading to PHVD, disrupts normal corticogenesis, alters myelin microstructure, causes a selective reduction in neurons, interneurons, and synapses. A1M, as a heme and free radicals scavenger, may attenuate WM damage, confirming that extracellular Hb is causative in ongoing neuroinflammation following IVH. Thus, A1M may be a possible treatment strategy in preterm infants with IVH. HFU represents a highly accurate tool for volumetric reconstruction of ventricles for diagnosis and management of PHVD

Magnetic resonance imaging, in situ hybridization, and immunohistochemistry-based analyses of early prenatal ethanol exposure-induced central nervous system abnormalities

Fetal alcohol spectrum disorders (FASD), the collection of defects resulting from prenatal alcohol (ethanol) exposure, has been the subject of basic and clinical investigation for four decades, but remains a major public health problem. At the severe end of the spectrum is fetal alcohol syndrome (FAS), which is characterized by the presence of growth retardation, craniofacial anomalies, and brain deficits. The research described herein was designed to advance our knowledge regarding ethanol's insult to the developing brain, with much of it directed toward testing the hypothesis that the application of magnetic resonance-based imaging to the examination of brain morphology, regional volumes and fiber tracts in ethanol-exposed fetal mice would facilitate new discoveries. As with other teratogens, it is well known that the type and severity of abnormality induced by ethanol is dependent upon the dose, timing, and pattern of maternal exposure. For this study, the CNS dysmorphology resulting from acute gestational day (GD) 7 maternal ethanol administration was examined in fetal mice utilizing state of the art imaging techniques. This time in mouse development is consistent with that in the third week of human gestation. Magnetic resonance microscopy (MRM) allowed for linear, volumetric and 3-dimensional morphologic analyses of ethanol-induced alterations in the fetal CNS and diffusion tensor imaging (DTI) provided for assessment of fiber tract abnormalities. In addition, routine histological techniques were utilized for detailed examination of the ventromedian forebrain in ethanol-exposed embryos and fetuses. Major new findings from these studies include the following regarding the consequences of acute GD7 ethanol exposure in mice 1) cerebral cortical heterotopias are induced; a discovery that was facilitated by MRM-based analyses, 2) fiber tract abnormalities involving the corpus callosum, anterior commissure, and fornix/fimbria occur, as evidenced by DTI, 3) fiber tract abnormalities, as identified in fetal mice, persist into periadolescent stages, 4) ventral forebrain insult preferentially involving the preoptic area and medial ganglionic eminences reduces Olig2 and GABA expression and alters the morphology of somatostatin-expressing cells. Overall, the results of this work promise to aid in clinical recognition, diagnosis, and prevention of FASD

Neonatal Neurobehavior and Diffusion MRI Changes in Brain Reorganization Due to Intrauterine Growth Restriction in a Rabbit Model

Background: Intrauterine growth restriction (IUGR) affects 5–10 % of all newborns and is associated with a high risk of abnormal neurodevelopment. The timing and patterns of brain reorganization underlying IUGR are poorly documented. We developed a rabbit model of IUGR allowing neonatal neurobehavioral assessment and high resolution brain diffusion magnetic resonance imaging (MRI). The aim of the study was to describe the pattern and functional correlates of fetal brain reorganization induced by IUGR. Methodology/Principal Findings: IUGR was induced in 10 New Zealand fetal rabbits by ligation of 40–50 % of uteroplacental vessels in one horn at 25 days of gestation. Ten contralateral horn fetuses were used as controls. Cesarean section was performed at 30 days (term 31 days). At postnatal day +1, neonates were assessed by validated neurobehavioral tests including evaluation of tone, spontaneous locomotion, reflex motor activity, motor responses to olfactory stimuli, and coordination of suck and swallow. Subsequently, brains were collected and fixed and MRI was performed using a high resolution acquisition scheme. Global and regional (manual delineation and voxel based analysis) diffusion tensor imaging parameters were analyzed. IUGR was associated with significantly poorer neurobehavioral performance in most domains. Voxel based analysis revealed fractional anisotropy (FA) differences in multiple brain regions of gray and white matter, including frontal, insular, occipital and temporal cortex, hippocampus, putamen, thalamus, claustrum, medial septa

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

Prenatal alcohol exposure reduces magnetic susceptibility contrast and anisotropy in the white matter of mouse brains

Prenatal alcohol exposure can result in long-term cognitive and behavioral deficits. Fetal alcohol spectrum disorder (FASD) refers to a range of permanent birth defects caused by prenatal alcohol exposure, and is the most common neurodevelopmental disorder in the US. Studies by autopsy and conventional structural MRI indicate that the midline structures of the brain are particularly vulnerable to prenatal alcohol exposure. Diffusion tensor imaging (DTI) has shown that abnormalities in brain white matter especially the corpus callosum are very common in FASD. Quantitative susceptibility mapping (QSM) is a novel technique that measures tissue’s magnetic property. Such magnetic property is affected by tissue microstructure and molecular composition including that of myelin in the white matter. In this work, we studied three major white matter fiber bundles of a mouse model of FASD and compared it to control mice using both QSM and DTI. QSM revealed clear and significant abnormalities in anterior commissure, corpus callosum, and hippocampal commissure, which were likely due to reduced myelination. Our data also suggested that QSM may be even more sensitive than DTI for examining changes due to prenatal alcohol exposure. Although this is a preclinical study, the technique of QSM is readily translatable to human brain

Association of war zone–related stress with alterations in limbic gray matter microstructure

IMPORTANCE: Military service members returning from theaters of war are at increased risk for mental illness, but despite high prevalence and substantial individual and societal burden, the underlying pathomechanisms remain largely unknown. Exposure to high levels of emotional stress in theaters of war and mild traumatic brain injury (mTBI) are presumed factors associated with risk for the development of mental disorders. OBJECTIVE: To investigate (1) whether war zone–related stress is associated with microstructural alterations in limbic gray matter (GM) independent of mental disorders common in this population, (2) whether associations between war zone–related stress and limbic GM microstructure are modulated by a history of mTBI, and (3) whether alterations in limbic GM microstructure are associated with neuropsychological functioning. DESIGN, SETTING, AND PARTICIPANTS: This cohort study was part of the TRACTS (Translational Research Center for TBI and Stress Disorders) study, which took place in 2010 to 2014 at the Veterans Affair Rehabilitation Research and Development TBI National Network Research Center. Participants included male veterans (aged 18-65 years) with available diffusion tensor imaging data enrolled in the TRACTS study. Data analysis was performed between December 2017 to September 2021. EXPOSURES: The Deployment Risk and Resilience Inventory (DRRI) was used to measure exposure to war zone–related stress. The Boston Assessment of TBI-Lifetime was used to assess history of mTBI. Stroop Inhibition (Stroop-IN) and Inhibition/Switching (Stroop-IS) Total Error Scaled Scores were used to assess executive or attentional control functions. MAIN OUTCOMES AND MEASURES: Diffusion characteristics (fractional anisotropy of tissue [FA(T)]) of 16 limbic and paralimbic GM regions and measures of functional outcome. RESULTS: Among 384 male veterans recruited, 168 (mean [SD] age, 31.4 [7.4] years) were analyzed. Greater war zone–related stress was associated with lower FA(T) in the cingulate (DRRI-combat left: P = .002, partial r = −0.289; DRRI-combat right: P = .02, partial r = −0.216; DRRI-aftermath left: P = .004, partial r = −0.281; DRRI-aftermath right: P = .02, partial r = −0.219), orbitofrontal (DRRI-combat left medial orbitofrontal cortex: P = .02, partial r = −0.222; DRRI-combat right medial orbitofrontal cortex: P = .005, partial r = −0.256; DRRI-aftermath left medial orbitofrontal cortex: P = .02, partial r = −0.214; DRRI-aftermath right medial orbitofrontal cortex: P = .005, partial r = −0.260; DRRI-aftermath right lateral orbitofrontal cortex: P = .03, partial r = −0.196), and parahippocampal (DRRI-aftermath right: P = .03, partial r = −0.191) gyrus, as well as with higher FA(T) in the amygdala-hippocampus complex (DRRI-combat: P = .005, partial r = 0.254; DRRI-aftermath: P = .02, partial r = 0.223). Lower FA(T) in the cingulate-orbitofrontal gyri was associated with impaired response inhibition (Stroop-IS left cingulate: P < .001, partial r = −0.440; Stroop-IS right cingulate: P < .001, partial r = −0.372; Stroop-IS left medial orbitofrontal cortex: P < .001, partial r = −0.304; Stroop-IS right medial orbitofrontal cortex: P < .001, partial r = −0.340; Stroop-IN left cingulate: P < .001, partial r = −0.421; Stroop-IN right cingulate: P < .001, partial r = −0.300; Stroop-IN left medial orbitofrontal cortex: P = .01, partial r = −0.223; Stroop-IN right medial orbitofrontal cortex: P < .001, partial r = −0.343), whereas higher FA(T) in the mesial temporal regions was associated with improved short-term memory and processing speed (left amygdala-hippocampus complex: P < .001, partial r = −0.574; right amygdala-hippocampus complex: P < .001, partial r = 0.645; short-term memory left amygdala-hippocampus complex: P < .001, partial r = 0.570; short-term memory right amygdala-hippocampus complex: P < .001, partial r = 0.633). A history of mTBI did not modulate the association between war zone–related stress and GM diffusion. CONCLUSIONS AND RELEVANCE: This study revealed an association between war zone–related stress and alteration of limbic GM microstructure, which was associated with cognitive functioning. These results suggest that altered limbic GM microstructure may underlie the deleterious outcomes of war zone–related stress on brain health. Military service members may benefit from early therapeutic interventions after deployment to a war zone

Atypical developmental trajectories of white matter microstructure in prenatal alcohol exposure: Preliminary evidence from neurite orientation dispersion and density imaging

IntroductionFetal alcohol spectrum disorder (FASD), a life-long condition resulting from prenatal alcohol exposure (PAE), is associated with structural brain anomalies and neurobehavioral differences. Evidence from longitudinal neuroimaging suggest trajectories of white matter microstructure maturation are atypical in PAE. We aimed to further characterize longitudinal trajectories of developmental white matter microstructure change in children and adolescents with PAE compared to typically-developing Controls using diffusion-weighted Neurite Orientation Dispersion and Density Imaging (NODDI).Materials and methodsParticipants: Youth with PAE (n = 34) and typically-developing Controls (n = 31) ages 8–17 years at enrollment. Participants underwent formal evaluation of growth and facial dysmorphology. Participants also completed two study visits (17 months apart on average), both of which involved cognitive testing and an MRI scan (data collected on a Siemens Prisma 3 T scanner). Age-related changes in the orientation dispersion index (ODI) and the neurite density index (NDI) were examined across five corpus callosum (CC) regions defined by tractography.ResultsWhile linear trajectories suggested similar overall microstructural integrity in PAE and Controls, analyses of symmetrized percent change (SPC) indicated group differences in the timing and magnitude of age-related increases in ODI (indexing the bending and fanning of axons) in the central region of the CC, with PAE participants demonstrating atypically steep increases in dispersion with age compared to Controls. Participants with PAE also demonstrated greater increases in ODI in the mid posterior CC (trend-level group difference). In addition, SPC in ODI and NDI was differentially correlated with executive function performance for PAE participants and Controls, suggesting an atypical relationship between white matter microstructure maturation and cognitive function in PAE.DiscussionPreliminary findings suggest subtle atypicality in the timing and magnitude of age-related white matter microstructure maturation in PAE compared to typically-developing Controls. These findings add to the existing literature on neurodevelopmental trajectories in PAE and suggest that advanced biophysical diffusion modeling (NODDI) may be sensitive to biologically-meaningful microstructural changes in the CC that are disrupted by PAE. Findings of atypical brain maturation-behavior relationships in PAE highlight the need for further study. Further longitudinal research aimed at characterizing white matter neurodevelopmental trajectories in PAE will be important

Genetic influences in emotional dysfunction and alcoholism-related brain damage

Alcoholism is a complex, multifactorial disorder involving problematic ethanol ingestion; it results from the interplay between genetic and environmental factors. Personality, likewise, is formed from a combination of inherited and acquired influences. Because selected dimensions of emotional temperament are associated with distinct neurochemical substrates contributing to specific personality phenotypes, certain aspects of abnormal emotional traits in alcoholics may be inherited. Emotions involve complex subjective experiences engaging multiple brain regions, most notably the cortex, limbic system, and cerebellum. Results of in vivo magnetic resonance imaging and post-mortem neuropathological studies of alcoholics indicate that the greatest cortical loss occurs in the frontal lobes, with concurrent thinning of the corpus callosum. Additional damage has been documented for the amygdala and hippocampus, as well as in the white matter of the cerebellum. All of the critical areas of alcoholism-related brain damage are important for normal emotional functioning. When changes occur in these brain regions, either as a consequence of chronic ethanol abuse or from a genetic anomaly affecting temperament and/or a vulnerability to alcoholism, corresponding changes in emotional functions are to be expected. In alcoholics, such changes have been observed in their perception and evaluation of emotional facial expressions, interpretation of emotional intonations in vocal utterances, and appreciation of the meaning of emotional materials