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PubMed2006

Dopamine: the rewarding years.

Dopamine has moved from being an insignificant intermediary in the formation of noradrenaline in 1957 to its present-day position as a major neurotransmitter in the brain. This neurotransmitter is involved in the control of movement and Parkinson's disease, the neurobiology and symptoms of schizophrenia and attention deficit hyperactivity disorder. It is also considered an essential element in the brain reward system and in the action of many drugs of abuse. This evolution reflects the ability of several famous names in neuropharmacology, neurology and psychiatry to apply new techniques to ask and answer the right questions. There is now excellent knowledge about the metabolism of dopamine, dopamine receptor systems and the structural organisation of dopamine pathways in the brain. Less is known about the function of the different receptors and how the various dopamine pathways are organised to produce normal behaviour, which exhibits disruption in the disease states mentioned. In particular, we have very limited information as to why and how the dopamine system dies or becomes abnormal in Parkinson's disease or a neurodevelopmental disorder such as schizophrenia. Dopamine neurones account for less than 1% of the total neuronal population of the brain, but have a profound effect on function. The future challenge is to understand how dopamine is involved in the integration of information to produce a relevant response rather than to study dopamine in isolation from other transmission systems. This integrated approach should lead to greater understanding and improved treatment of diseases involving dopamine.

Dopamine↗

PubMed2001

A comparison of WAIS-R profiles in adults with high-functioning autism or differing subtypes of learning disability.

To examine cognitive differences among adults with differing developmental disorders, a comparison of Wechsler Adult Intelligence Scale-Revisedprofiles was made with samples of 35 individuals with high-functioning autism (HFA) and 102 individuals with adult learning disability (LD). All participants had Verbal andPerformance IQ scores of 70 or higher. The LD group was divided into 3 subtypes based on relative achievement levels in mechanical reading and arithmetic. The group with HFA had a profile characterized by a high score on Block Design with a low Comprehension score. The HFA group most resembled the LD subtype that had superior achievement in reading relative to arithmetic, with the exception of their poor performance on measures of social perception and judgment. Results are discussed in terms of the substantial differences in cognitive structure between these 2 neurodevelopmental disorders and are considered in the context of the learning deficits reported for Asperger 's Disorder and nonverbal learning disability.

Achievement↗

PubMed2001

Identifying maternal self-reported alcohol use associated with fetal alcohol spectrum disorders.

BACKGROUND: The incidence of Fetal Alcohol Syndrome (FAS) has been estimated at 1 to 3 per 1,000 live births. Fetal Alcohol Spectrum Disorders (FASD) (which include FAS) are estimated to occur in about 1 in 100 births. Cessation of drinking during pregnancy can improve the outcome even if the unborn child is already affected. For individuals born with FASD, an early diagnosis appears to be a protective factor against secondary disabilities. A quick screening tool to identify newborn children at risk has been elusive. METHODS: A simple descriptive presentation is offered that shows where 36 individuals with FASD were found from among the many patterns and amounts of prenatal alcohol use that were reported by a sample of 1,439 pregnant women whose offspring were later examined within the first 7 years of life. RESULTS: Individuals with FASD (i.e., those with FAS, fetal alcohol effects, alcohol-related neurodevelopmental disorder ) were found within two aggregates of alcohol scores that together recommend a set of three to four alcohol questions. Within this derivation sample, one scoring of the questions yields almost 78% sensitivity and 97% specificity for FASD. Another scoring of the same instrument yields 100% sensitivity with 90% specificity. CONCLUSIONS: These new data may facilitate early identification of offspring who may be most in need of early intervention, namely those born with FASD.

Adolescent↗

PubMed2024

Advances in serum thyroid hormone levels and seizures.

Epilepsy, a common neurological disorder, is characterized by paroxysmal, short-term, repetitive, and stereotypical features, significantly impacting patients' quality of life. Currently, the pathogenesis of epilepsy remains incompletely understood. Changes in neuronal excitability, imbalances in glutamate and gamma-aminobutyric acid (GABA) levels, alterations in the activity of GABA receptors, and dysfunction of GABA receptors are considered closely related to its occurrence. Thyroid hormones, vital for human growth and development, also play a crucial role in the nervous system. They mediate oxidative stress, influence reactive oxygen species production, affect mitochondrial function and neuronal excitability, and modulate glutamate and GABA levels. Also, they combine with thyroid hormone receptors and exert genomic effects by regulating the expression of numerous genes. However, once there are defects in thyroid hormone signaling, these defects may lead to severe neurodevelopmental disorders that are associated with an increased frequency of seizures. The impact of antiseizure medications (ASMs) on serum thyroid hormone levels, particularly traditional ASMs, has been extensively studied. It is reported that conventional ASMs such as phenobarbital, phenytoin sodium, carbamazepine, and valproate sodium were more likely to induce subclinical hypothyroidism (elevated TSH with normal FT4) or isolated hypothyroidism (decreased FT4 with normal TSH). However, the new ASMs, such as levetiracetam, have no effect on thyroid hormone levels. Together, seizures not only affect thyroid hormone levels, but abnormal thyroid hormone levels can also influence seizures. However, the precise mechanism underlying the interaction between serum thyroid hormone levels and seizures remains unclear. This review aims to explore the relationship between thyroid hormone levels and seizures, along with the underlying mechanisms.

Humans↗

PubMedDate not supplied

Diagnosis of FAS: a comparison of the Fetal Alcohol Syndrome Diagnostic Checklist and the Institute of Medicine Criteria for Fetal Alcohol Syndrome.

UNLABELLED: Fetal alcohol syndrome (FAS) is a common cause of neuropsychiatric disorders, growth impairment and craniofacial abnormalities. The syndrome may be more common than has been previously reported. Considerable controversy exists over the approaches for diagnosis of the syndrome. METHOD: In this study, we examined the rate of agreement for two diagnostic schema using 385 subjects that had been referred for assessment of possible FAS. Cases had initially been diagnosed using the Fetal Alcohol Syndrome Diagnostic Checklist (FASDC). We then reviewed the chart of each of the 385 subjects referred and assigned each subject to a category from the Institute of Medicine (IOM) Criteria or to a NOFAS category. We then compared the IOM categories with the FASDC. RESULTS: Rates of agreement with the IOM Criteria ranged from 59-71% using the FASDC. Poorest agreement was found in conjunction with partial FAS (PFAS)/alcohol-related neurodevelopmental disorder (ARND). Removal of exposure data from the scores greatly affected accuracy for the FASDC scores. DISCUSSION: The schema had only modest rates of agreement for classification of subjects with a diagnosis of FAS. This study does not determine if the diagnosis used in the development of the cohort was accurate. Further study utilizing multiple diagnostic schema in a single population will help examine the rates of diagnostic agreement between differing diagnostic schema. A valuable cohort to study would be the subjects in the CDC surveillance system. A perspective study utilizing a single cohort and applying multiple diagnostic criteria at the same time would be useful.

Diagnosis, Differential↗

PubMed1999

Intelligence patterns among children with high-functioning autism, phenylketonuria, and childhood head injury.

High-functioning children with autistic-spectrum disorder show the typical pattern of lower Comprehension relative to their own scores on Block Design. This profile is shared, almost exactly, by age- and IQ-matched children with poorer control PKU. Quite distinct profiles are shown by children with better control PKU, who show no difference between Block Design and Comprehension, and by children with head injury involving frontal lobe contusion, who show slightly better Comprehension that Block Design. The data bear on several questions: the relation between Comprehension deficits and language functions measured by Vocabulary; the limits of the advantages conveyed by higher IQ to autistic individuals; whether impaired Comprehension in autism indexes persisting symptoms and/or impairments on theory of mind tasks; the possibility that dopamine deficiency is common to autism and poorer control PKU; and the need for future research aimed at understanding the relations among neurodevelopmental disorders.

Analysis of Variance↗

PubMed2005

Alcohol is a potent stimulant of immature neuronal networks: implications for fetal alcohol spectrum disorder.

Ethanol consumption during development affects the maturation of hippocampal circuits by mechanisms that are not fully understood. Ethanol acts as a depressant in the mature CNS and it has been assumed that this also applies to immature neurons. We investigated whether ethanol targets the neuronal network activity that is involved in the refinement of developing hippocampal synapses. This activity appears during the growth spurt period in the form of giant depolarizing potentials (GDPs). GDPs are generated by the excitatory actions of GABA and glutamate via a positive feedback circuit involving pyramidal neurons and interneurons. We found that ethanol potently increases GDP frequency in the CA3 hippocampal region of slices from neonatal rats. It also increased the frequency of GDP-driven Ca2+ transients in pyramidal neurons and increased the frequency of GABA(A) receptor-mediated spontaneous postsynaptic currents in CA3 pyramidal cells and interneurons. The ethanol-induced potentiation of GABAergic activity is probably the result of increased quantal GABA release at interneuronal synapses but not enhanced neuronal excitability. These findings demonstrate that ethanol is a potent stimulant of developing neuronal circuits, which might contribute to the abnormal hippocampal development associated with fetal alcohol syndrome and alcohol-related neurodevelopmental disorders.

Alcohol-Induced Disorders, Nervous System↗

PubMed2006

Sensorimotor gating deficits in adults with autism.

BACKGROUND: Prepulse inhibition (PPI) is an operational measure of sensorimotor gating and is impaired in a family of neuropsychiatric disorders characterized by abnormalities of inhibitory function. Adults with autistic disorder (AD) exhibit clinical features of inhibitory deficits, such as restrictive and repetitive behaviors, that may be explained by deficits in sensorimotor gating. METHODS: Acoustic startle reactivity, habituation, and PPI (30-, 60-, 120-msec interstimulus intervals) were assessed in 14 adult men diagnosed with AD and 16 typically developing normal comparison (NC) participants. All participants were administered measures of intelligence and frontal-executive functioning. RESULTS: Adults with AD exhibited significantly less PPI in the 60-msec condition than NC participants, which was correlated with increased ratings of restricted and repetitive behaviors. The groups did not differ on measures of startle amplitude or overall habituation. There was, however, a significant group-by-block habituation effect. Furthermore, PPI was not related to intelligence but was moderately associated with performance on a measure of frontal-executive functioning. CONCLUSIONS: Adults with AD have sensorimotor gating deficits similar to other neurodevelopmental disorders, implicating a failure of normal inhibitory regulation of sensory, motor, and attentional mechanisms. Thus, PPI deficits may be indirectly linked to one of the hallmark features of AD.

Acoustic Stimulation↗

PubMed1997

The Nithsdale Schizophrenia Surveys. 16. Breast-feeding and schizophrenia: preliminary results and hypotheses.

BACKGROUND: Schizophrenia may in some cases be a neurodevelopmental disorder. Breast milk is important to the developing brain. Might a lack of breast milk be an environmental risk factor in schizophrenia? METHOD: Mothers of 45 schizophrenic patients in Nithsdale, southwest Scotland, completed a questionnaire about whether or not their offspring had been breast-fed. RESULTS: The incidence of breast-feeding in patients was 29% and in sibs 38%. Most patients were born in the 1940s and 1950s. The incidence in patients born in these two decades, 33 and 26%, respectively, was significantly lower than in Scottish surveys in 1946 (81%) and 1958 (51%). Those patients who had not been breast-fed had more schizoid and schizotypal personality traits in childhood and a poorer social adjustment than their sibs; breast-fed patients did not differ from their sibs. CONCLUSIONS: Fewer schizophrenic patients than normal were breast-fed. Lack of breast milk may be a risk factor in the neurodevelopmental form of schizophrenia.

Adult↗

PubMed2005

CDKL5/Stk9 kinase inactivation is associated with neuronal developmental disorders.

X-linked cyclin-dependent kinase-like 5 (CDKL5 or STK9) has recently been implicated in atypical Rett and X-linked West syndromes, severe neurological disorders associated with mental retardation, loss of communication and motor skills and infantile spasms and seizures in predominantly females. Besides CDKL5, these disease phenotypes are also linked to mutations in the MECP2 and ARX genes. Here, we have expressed and characterized CDKL5 and its mutant forms. CDKL5 is a 118 kDa protein that is widely distributed in all tissues, with highest levels in brain, thymus and testes. Whole mount embryo staining reveals CDKL5 to be ubiquitous. Within cells, CDKL5 is localized primarily in the nucleus. Removal of the C-terminal domain increases CDKL5 expression, enhances autophosphorylation activity and causes perinuclear localization, indicating that the C-terminus regulates CDKL5 function. Although we detect MeCP2 but not ARX binding to CDKL5, our results suggest that neither of these proteins are direct substrates of the CDKL5 kinase. Finally, the CDKL5 mutations associated with the disease phenotype cause loss of kinase activity as assessed by autophosphorylation. These results suggest that inactivation of the CDKL5 kinase can lead to severe neurodevelopmental disorders.

Amino Acid Motifs↗

PubMed2025

A founder variant in TBCB is associated with global developmental delay, autism spectrum, and spastic paraparesis.

PURPOSE: Hereditary spastic paraparesis (HSP) is a genetically diverse group of Mendelian disorders characterized by length-dependent axonal degeneration. Microtubule dysfunction is a known mechanism in HSP that impairs axonal dynamics. TBCB encodes tubulin-folding cofactor B (TBCB), which, along with TBCE, regulates αβ-heterodimer dynamics and neuronal axonal growth. Here, we describe a new form of complicated HSP caused by a founder variant in TBCB. METHODS: Exome sequencing revealed a homozygous c.589T>A p.(Tyr197Asn) variant in TBCB in a cohort of 10 individuals assembled through genematching tools. Protein function was assessed using Saccharomyces cerevisiae ortholog ALF1, and a CRISPR-Cas9-generated homologous mutant in Drosophila melanogaster. TBCB expression and localization were examined in fibroblasts using western blot and immunofluorescence. RESULTS: Participants displayed late-childhood-onset spastic paraparesis, global developmental delay, and autism spectrum. TBCB protein levels were reduced in affected fibroblasts. The ALF1 mutant in yeast increased benomyl sensitivity, resembling a loss-of-function phenotype. In Drosophila melanogaster, the homologous mutant led to reduced survival and impaired climbing ability. CONCLUSION: We describe a novel neurodevelopmental disorder with spastic paraparesis and a high carrier rate in the Ashkenazi Jewish population. Our results indicate that TBCB has a vital role in the development of central nervous system and potentially in axonal function in humans.

Humans↗

PubMed2006

A role for the 'magnocellular advantage' in visual impairments in neurodevelopmental and psychiatric disorders.

Evidence exists implicating abnormal visual information processing and visually driven attention in a number of neurodevelopmental and psychiatric disorders, suggesting that research into such disorders may benefit from a better understanding of more recent advances in visual system processing. A new integrated model of visual processing based on primate single cell and human electrophysiology may provide a framework, to understand how the visual system is involved, by implicating the magnocellular pathway's role in driving attentional mechanisms in higher-order cortical regions, what we term the 'magnocellular advantage'. Evidence is also presented demonstrating visual processing occurs considerably faster than previously assumed, and emphasising the importance of top-down feedback signals into primary visual cortex, as well as considering the possibility of lateral connections from dorsal to ventral visual areas. Such organisation is argued to be important for future research highlighting visual aspects of impairment in disorders as diverse as schizophrenia and autism.

Animals↗

PubMed2003

Postmaturity in a genetic subtype of schizophrenia.

OBJECTIVE: To determine whether postmaturity (gestation > 41 weeks), small for gestational age (SGA), and other pregnancy and birth complications that may elevate risk for neurodevelopmental disorders, are associated with elevated risk for schizophrenia in 22q11 Deletion Syndrome (22qDS), a genetic subtype of schizophrenia. METHOD: Antepartum and intrapartum features were examined in 20 adults with 22qDS-schizophrenia and three comparison groups: newborn encephalopathy (n = 164) and healthy newborn controls (n = 400) from Badawi et al.'s (Br Med J 1998, 317: 1549) study, and 16 non-psychotic 22qDS adults (22qDS-NP). RESULTS: Postmaturity (OR 13.0, 95% CI 3.95, 42.77; P < 0.001) and SGA (OR 3.59, 95% CI 1.23, 10.5; P = 0.03) were more prevalent in 22qDS-SZ than controls. Postmaturity was non-significantly more prevalent in 22qDS-SZ than in newborn encephalopathy (P = 0.06) or 22qDS-NP (P = 0.2). SGA showed similar rates in the two 22qDS groups and newborn encephalopathy, but was more prevalent in 22qDS-NP than controls (P = 0.05). CONCLUSION: The results suggest that postmaturity may be associated with expression of schizophrenia in a 22qDS subtype of schizophrenia. SGA may be a non-specific marker of neurodevelopmental disturbance.

Adult↗

PubMed2006

Critical prenatal and postnatal periods for persistent effects of dexamethasone on serotonergic and dopaminergic systems.

Glucocorticoid administration to preterm infants is associated with neurodevelopmental disorders. We treated developing rats with dexamethasone (Dex) at 0.05, 0.2, or 0.8 mg/kg, doses below or spanning the range in clinical use, testing the effects of administration during three different stages: gestational days 17-19, postnatal days 1-3 or postnatal days 7-9. In adulthood, we assessed the impact on synaptic biomarkers for serotonin (5-hydroxytryptamine (5HT)) systems. Across all three regimens, Dex administration evoked upregulation of cerebrocortical 5HT1A and 5HT2 receptors and the presynaptic 5HT transporter, greatest for 5HT1A receptors. The effects were fully evident even at the lowest dose. In contrast, 5HT levels in the cerebral cortex and hippocampus showed disparate patterns of temporal sensitivity, with no change after gestational treatment, an increase with the early postnatal regimen, and a decrease with the later postnatal exposure. None of the changes in 5HT concentrations were offset by adaptive changes in the fractional 5HT turnover rate. Furthermore, the critical period of sensitivity seen for 5HT levels differed from that of dopamine even within the same brain region. These findings suggest that developmental exposure to Dex during the critical neurodevelopmental period corresponding to its use in preterm infants, elicits selective changes in 5HT and dopaminergic synaptic function over and above its effects on general aspects of neural cell development, below the threshold for somatic growth impairment, and even at doses below those used clinically. Accordingly, adverse neurobehavioral consequences may be inescapable in glucocorticoid therapy of preterm infants.

3,4-Dihydroxyphenylacetic Acid↗

PubMedDate not supplied

Reduced levels of mercury in first baby haircuts of autistic children.

Reported rates of autism have increased sharply in the United States and the United Kingdom. One possible factor underlying these increases is increased exposure to mercury through thimerosal-containing vaccines, but vaccine exposures need to be evaluated in the context of cumulative exposures during gestation and early infancy. Differential rates of postnatal mercury elimination may explain why similar gestational and infant exposures produce variable neurological effects. First baby haircut samples were obtained from 94 children diagnosed with autism using Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM IV) criteria and 45 age- and gender-matched controls. Information on diet, dental amalgam fillings, vaccine history, Rho D immunoglobulin administration, and autism symptom severity was collected through a maternal survey questionnaire and clinical observation. Hair mercury levels in the autistic group were 0.47 ppm versus 3.63 ppm in controls, a significant difference. The mothers in the autistic group had significantly higher levels of mercury exposure through Rho D immunoglobulin injections and amalgam fillings than control mothers. Within the autistic group, hair mercury levels varied significantly across mildly, moderately, and severely autistic children, with mean group levels of 0.79, 0.46, and 0.21 ppm, respectively. Hair mercury levels among controls were significantly correlated with the number of the mothers' amalgam fillings and their fish consumption as well as exposure to mercury through childhood vaccines, correlations that were absent in the autistic group. Hair excretion patterns among autistic infants were significantly reduced relative to control. These data cast doubt on the efficacy of traditional hair analysis as a measure of total mercury exposure in a subset of the population. In light of the biological plausibility of mercury's role in neurodevelopmental disorders, the present study provides further insight into one possible mechanism by which early mercury exposures could increase the risk of autism.

Adolescent↗

PubMed2005

Behavioral alterations in rats prenatally exposed to valproic acid: animal model of autism.

Autism is a severe behavioral disorder characterized by pervasive impairments in social interactions, deficits in verbal and nonverbal communication, and stereotyped, repetitive patterns of behaviors and interests. Recently, a new rodent model of autism was created by exposure of rat fetuses to valproic acid (VPA) on the 12.5th day of gestation (VPA rats). The model has striking anatomical, pathological, and etiological similarities to human data; however, it has not been characterized behaviorally. In order to determine if VPA rats present behavioral aberrations observed in autism, their behavior was extensively evaluated in a battery of tests. The results of the present experiments demonstrate that VPA rats exhibit: (1) lower sensitivity to pain and higher sensitivity to nonpainful stimuli, (2) diminished acoustic prepulse inhibition, (3) locomotor and repetitive/stereotypic-like hyperactivity combined with lower exploratory activity, and (4) decreased number of social behaviors and increased latency to social behaviors. In addition, VPA rats showed delayed maturation, lower body weight, delayed motor development, and attenuated integration of a coordinated series of reflexes, delayed nest-seeking response mediated by olfactory system, and normal negative geotaxis. Interestingly, all behavioral aberrations described in this paper appear before puberty, which could distinguish the VPA rat model of autism from other animal models of neurodevelopmental disorders, especially rodent models of schizophrenia. Our results bring further support to validity of the proposed VPA animal model of autism, suggesting similarities between the observed pattern of behavioral alterations in VPA rats and features of disturbed behavior in autistic patients.

Acoustic Stimulation↗

PubMed2005

Abnormal infant neurodevelopment predicts schizophrenia spectrum disorders.

OBJECTIVE: The aim of this study was to detect infants who carry a schizophrenic genotype and study the development of schizophrenia spectrum disorders (SZSD) from birth. INTRODUCTION: In the 1940s, Bender described uneven maturation in childhood schizophrenics and in 1952 found this in the infant histories of 6 schizophrenic children. METHODS: We tested a possible index for defective neural integration in infants termed "pandysmaturation" (PDM). This required retarded cranial growth plus retarded and erratic gross motor development on a single exam. Twelve offspring of hospitalized schizophrenic mothers and 12 infants in a "Well Baby Clinic," were examined 10 times between birth and 2 years of age. Psychiatric interviews and psychological testing were done at 10, 15, and 22 years of age, plus follow-up at 27-35 years of age. RESULTS: Six infants had PDM at 2, 6, or 13 months of age. Five individuals have been blindly diagnosed (by KSK) as having lifetime SZSD; all 5 had PDM before 8 months. Chi-square one-tailed tests confirmed the predictions: (1) PDM was related to subsequent SZSD (chi(2) = 11.43; p < 0.0005); (2) schizophrenic mothers had more infants with PDM than nonschizophrenic mothers (chi(2) = 3.28; p < 0.05); and (3) schizophrenic mothers had more SZSD offspring than nonschizophrenic mothers (chi(2) = 6.39; p < 0.0125). DISCUSSION: These first behavioral observations of aberrant neurodevelopment in pre- SZSD infants support the evidence of early neurodevelopmental disorder seen in studies of brain pathology in SZSD adults.

Adolescent↗

PubMed2002

Diversity of neuromuscular pathology in lethal multiple pterygium syndrome.

Lethal multiple pterygium syndrome (LMPS) is an uncommon fetal-onset disorder of unknown etiology. The pathogenesis of LMPS has been suggested to be early-onset fetal akinesia, fragile collagen, or generalized edema. Information on the neuromuscular pathology of LMPS in the literature is generally scanty. We present the findings from a review of 14 fetuses with features of LMPS from the archives of the Hammersmith Hospital Perinatal Pathology Department. Autopsy reports, photographs, fetograms, and histological sections were examined, and additional special stains and immunostaining were performed on muscle sections. In five cases, there was evidence of autosomal recessive inheritance. One case was later shown to be due to glycogen storage disease type IV. The skeletal muscle bulk was reduced in all fetuses and the remaining muscle showed a range of histological appearances including vacuolar degeneration, dystrophy, a generalized or patchy myotubular appearance, and generalized hypotrophy. In one, the histological appearance was essentially normal. Two cases had abnormalities in the brain. Large motor neurons were present in the anterior spinal horns of all fetuses in whom the spinal cord could be examined. There was no evidence of cartilaginous joint fusion. We conclude that LMPS is the phenotype resulting from fetal akinesia commencing in the first or early second trimester. In the majority of cases, the precise underlying cause will not be identified, however, occasionally a metabolic or neurodevelopmental disorder or a specific primary myopathy may be demonstrated, providing adequate autopsy investigations are undertaken.

Abnormalities, Multiple↗