Neurobiology of autism

The autism-associated loss of δ-catenin functions disrupts social behaviors

δ-catenin is expressed in excitatory synapses and functions as an anchor for the glutamatergic AMPA receptor (AMPAR) GluA2 subunit in the postsynaptic density. The glycine 34 to serine (G34S) mutation in the δ-catenin gene is found in autism spectrum disorder (ASD) patients and induces loss of δ-catenin functions at excitatory synapses, which is presumed to underlie ASD pathogenesis in humans. However, how the G34S mutation causes loss of δ-catenin functions to induce ASD remains unclear. Here, using neuroblastoma cells, we discover that the G34S mutation generates an additional phosphorylation site for glycogen synthase kinase 3β (GSK3β). This promotes δ-catenin degradation and causes the reduction of δ-catenin levels, which likely contributes to the loss of δ-catenin functions. Synaptic δ-catenin and GluA2 levels in the cortex are significantly decreased in mice harboring the δ-catenin G34S mutation. The G34S mutation increases glutamatergic activity in cortical excitatory neurons while it is decreased in inhibitory interneurons, indicating changes in cellular excitation and inhibition. δ-catenin G34S mutant mice also exhibit social dysfunction, a common feature of ASD. Most importantly, inhibition of GSK3β activity reverses the G34S-induced loss of δ-catenin function effects in cells and mice. Finally, using δ-catenin knockout mice, we confirm that δ-catenin is required for GSK3β inhibition-induced restoration of normal social behaviors in δ-catenin G34S mutant animals. Taken together, we reveal that the loss of δ-catenin functions arising from the ASD-associated G34S mutation induces social dysfunction via alterations in glutamatergic activity and that GSK3β inhibition can reverse δ-catenin G34S-induced synaptic and behavioral deficits.

Significance Statement

δ-catenin is important for the localization and function of glutamatergic AMPA receptors at synapses in many brain regions. The glycine 34 to serine (G34S) mutation in the δ-catenin gene is found in autism patients and results in the loss of δ-catenin functions. δ-catenin expression is also closely linked to other autism-risk genes involved in synaptic structure and function, further implying that it is important for the autism pathophysiology. Importantly, social dysfunction is a key characteristic of autism. Nonetheless, the links between δ-catenin functions and social behaviors are largely unknown. The significance of the current research is thus predicated on filling this gap by discovering the molecular, cellular, and synaptic underpinnings of the role of δ-catenin in social behaviors.

A family study of symbolic learning and synaptic plasticity in autism spectrum disorder

The current study presents a male with autism spectrum disorder (ASD) and a 3q29 deletion, and three healthy first-degree relatives. Our magnetic resonance imaging (MRI) dataset included a healthy control subset. We describe a comprehensive multimodal approach, including equivalence class formation, neurocognitive testing, MRI, and electroencephalography (EEG)-based cortical plasticity, which can provide new insights into socio-communicative and learning impairments and neural underpinnings in ASD. On neurocognitive testing, the proband showed reduced processing speed, attending behavior, and executive function. He required more training trials in equivalence class training compared with family members and exhibited impaired priming of words compared with priming with images. The proband had smaller intracranial volume and surface area and a larger visual evoked potential (VEP) C1 amplitude than family members and intact long-term potentiation (LTP)-like visual cortex plasticity. Together, these results suggest that 3q29 deletion-related ASD is associated with impaired problem-solving strategies in complex socio-communicative and learning tasks, smaller intracranial and surface area, altered VEP amplitude, and normal LTP-like visual cortex plasticity. Further studies are needed to clarify whether this multimodal approach can be used to identify ASD subgroups with distinct neurobiological alterations and to uncover mechanisms underlying socio-communicative and learning impairments. Lay Summary: We studied learning, brain activity, and brain structure in a person with autism and a genetic aberration, and his close relatives. Compared with relatives, the person with autism required more training for learning, and visual learning was better than verbal learning. This person had some changes in the activity of the visual cortex, and the size and the surface area of the brain were reduced. Knowledge about learning and brain mechanisms is valuable for the development of training programs for individuals with autism.

Changes of Cerebellar Cortex in a Valproic Acid-Induced Rat Model of Autism

In this study, 32 male Sprague-Dawley rats (8 for each group) were used in total to examine the effects of valproic acid on rat cerebellum. It was determined that the experimental group received valproic acid (600mg/kg) on embryonic day 15 and postnatal day 11, whereas the control group was treated with saline on the same days. Moreover, on the postnatal 30^th day, the cerebellums of all pups were removed and prepared for light and electron microscopy. The numerical density of granule cells in the cerebellum of experimental groups of rats increased whereas the numerical density of Purkinje cells decreased. Furthermore, the granule cells had a smaller mean nuclear diameter in one of the experimental groups while the Purkinje cells had in both experimental groups than those in the comparison group. Thus, the numerical density of synaptic discs and their mean diameter in the cerebellar granular layer of experimental groups were significantly decreased compared to the corresponding controls; also, the synapse-to-neurons ratio, a parameter indicating interneural connectivity, was the same. Consequently, it was seen that valproic acid administration to pups in prenatal or early postnatal days causes changes in number of neurons and synapses in the cerebellum of rats.

Neuronal morphology alterations in autism and possible role of oxytocin

Current understanding of the neuroanatomical abnormalities in autism includes gross anatomical changes in several brain areas and microstructural alterations in neuronal cells as well. There are many controversies in the interpretation of the imaging data, evaluation of volume and size of particular brain areas, and their functional translation into a broad autism phenotype. Critical questions of neuronal pathology in autism include the concept of the reversible plasticity of morphological changes, volume alterations of brain areas, and both short- and long-term consequences of adverse events present during the brain development. At the cellular level, remodeling of the actin cytoskeleton is considered as one of the critical factors associated with the autism spectrum disorders. Alterations in the composition of the neuronal cytoskeleton, in particular abnormalities in the polymerization of actin filaments and their associated proteins underlie the functional consequences in behavior resulting in symptoms and clinical correlates of autism spectrum disorder. In the present review, a special attention is devoted to the role of oxytocin in experimental models of neurodevelopmental disorders manifesting alterations in neuronal morphology.

Alterations in volumes and MRI features of amygdala in Chinese autistic preschoolers associated with social and behavioral deficits

To examine the amygdala volume in 2–5-year-old preschool children with autism and explore the relationship between amygdala volumes based on MRI findings and clinical features. A total of 39 cases with clinically diagnosed autism were collected. The oblique coronal T1 weighted image (T1WI) sequence was used to measure the volume of amygdala and the MRI signals were measured and analyzed. The data were compared to that of 24 age-matched healthy children and correlated to the clinical manifestations. The autism and the control groups were subject to brain scanning in 1 week after Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) review. The 39 cases, diagnosed with autism, were associated with social and behavioral deficits through clinical observation, physical and neurological examination, and assessments according to DSM IV, and the range of ABC scores in the autism group was 47–124, with an average score of 84.7 ± 24.1. Abnormal MRI signals were found in 19/78 (24.4%) amygdala in the autism group, the amygdala lesions showed punctuate or flaky low signal, slightly low signal, low to iso-signal, slightly high signal, or iso to high-signal intensity on T1 weighted three-dimendional fast low angle shot(T1FL3D) images. The right amygdala volume average was 1.088 ± 0.38 cm³, while that of the left amygdala was 1.04 ± 0.41 cm³, without any statistically significant difference (t = 0.533, p = 0.596) in the autism group. Among the 24 cases in the control group, the right amygdala volume average was 0.754 ± 0.194 cm³, while that of the left amygdala was 0.666 ± 0.252 cm³; the autism group had a significantly larger right and left amygdala volumes as compared to the age-matched typically developing group with a significant positive correlation between age and right amygdala volume (r = 0.406, p = 0.01). The preschool children with autism had significantly larger bilateral amygdala volumes as compared to age-matched typically developing children, the amygdala lesions may show abnormal signal. A relationship between age and right amygdala volume in the preschool children with autism was established.

Evaluation of the effectiveness of MNRI therapy in children with autism based on the ATEC test – a preliminary report

Autism (ASD) is a multiform disorder of unexplored etiology. Therapeutic treatment is therefore symptomatic0 and due to the complexity and variety of symptoms, it must be individualized. Therapists reach for various methods and forms of work with an autistic patient. In this situation, there is also a need to evaluate the therapeutic procedure and the choice of methods that will help assess the effectiveness of therapy. One of the proposed activities is therapeutic modality MNRI (Masgutova Neurosensorimotor Reflex Integration), while the standard ATEC test is used to assess the effectiveness of therapy. The MNRI method deals with the functioning of basic reflexes, the movement system and its impact on the developmental and learning processes. The MNRI method is aimed at restoring normal neurosensoric development and integration of reflex patterns, motor coordination systems and skills enabling movement functioning, behavioural regulation, emotional and cognitive functions. Therapy consists in activating reflex patterns to stimulate the natural resources of the brain, the body, strengthening memory and neurosensotimotive as well as motor integration. The aim of the study was to evaluate the effectiveness of MNRI therapy in children with autism based on the ATEC test. The study involved 60 children diagnosed with autism (F84.0) according to ICD-10 criteria. The average age of patients was 10.7 years. Each participant of the project took an active part in the 11-day rehabilitation process according to the MNRI programme. The standardized ATEC test was used to assess the effectiveness of therapy. Analysis of the results of the ATEC test before and after the 11-day rehabilitation in autistic patients showed positive effects of MNRI therapy among 43.5% of the subjects. These effects included, for part I - in terms of communication, an increase was noted by 9.2%; for part II – socialization0 58.3%; part III - sensory feeling, cognitive awareness, 47.2% and in part IV - physical health, emotions, behaviour, 57.9%. MNRI therapy positively influenced the examined group of autistic patients. Particularly noticeable improvement was expressed in the reduction of self-inflicted harm (65%), reduced hypersensitivity and improvement in sound tolerance (80%), improvement of awareness of one’s own body's (60%); greater calmness, self-control (80%). The therapy is safe, painless, has no negative effects. This article is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. null

Brief Report: Flanker Visual Filtering Ability in Older Adolescents with Autism Spectrum Disorder

Recent research has documented impaired ability to resist interference from visual distractors in individuals with autism spectrum disorder (ASD) and suggests that this phenomenon may be more pronounced in young versus older children (Christ et al., Neuropsychology 25(6):690-701, 2011). The present study extends previous findings by examining visual filtering inhibitory ability within an older adolescent population. A flanker visual filtering task was administered to 36 adolescents with ASD and 44 adolescents without ASD (age: 11-20 years). Analysis revealed no evidence of group differences in visual filtering performance. Taken together with previous research, these results suggest that during early adolescence the previously observed impairment may resolve or compensatory strategies develop, allowing individuals with ASD to perform as well as their neurotypical peers.

Common Ribs of Inhibitory Synaptic Dysfunction in the Umbrella of Neurodevelopmental Disorders

The term neurodevelopmental disorder (NDD) is an umbrella term used to group together a heterogeneous class of disorders characterized by disruption in cognition, emotion, and behavior, early in the developmental timescale. These disorders are heterogeneous, yet they share common behavioral symptomatology as well as overlapping genetic contributors, including proteins involved in the formation, specialization, and function of synaptic connections. Advances may arise from bridging the current knowledge on synapse related factors indicated from both human studies in NDD populations, and in animal models. Mounting evidence has shown a link to inhibitory synapse formation, specialization, and function among Autism, Angelman, Rett and Dravet syndromes. Inhibitory signaling is diverse, with numerous subtypes of inhibitory interneurons, phasic and tonic modes of inhibition, and the molecular and subcellular diversity of GABA_A receptors. We discuss common ribs of inhibitory synapse dysfunction in the umbrella of NDD, highlighting alterations in the developmental switch to inhibitory GABA, dysregulation of neuronal activity patterns by parvalbumin-positive interneurons, and impaired tonic inhibition. Increasing our basic understanding of inhibitory synapses, and their role in NDDs is likely to produce significant therapeutic advances in behavioral symptom alleviation for interrelated NDDs.

Digital gene atlas of neonate common marmoset brain

Interest in the common marmoset (Callithrix jacchus) as a primate model animal has grown recently, in part due to the successful demonstration of transgenic marmosets. However, there is some debate as to the suitability of marmosets, compared to more widely used animal models, such as the macaque monkey and mouse. Especially, the usage of marmoset for animal models of human cognition and mental disorders, is still yet to be fully explored. To examine the prospects of the marmoset model for neuroscience research, the Marmoset Gene Atlas (https://gene-atlas.bminds.brain.riken.jp/) provides a whole brain gene expression atlas in the common marmoset. We employ in situ hybridization (ISH) to systematically analyze gene expression in neonate marmoset brains, which allows us to compare expression with other model animals such as mouse. We anticipate that these data will provide sufficient information to develop tools that enable us to reveal marmoset brain structure, function, cellular and molecular organization for primate brain research.

Insulin-Like Growth Factors in the Pathogenesis of Neurological Diseases in Children

Insulin-like growth factors play a key role for neuronal growth, differentiation, the survival of neurons and synaptic formation. The action of IGF-1 is most pronounced in the developing brain. In this paper we will try to give an answer to the following questions: Why are studies in children important? What clinical studies in neonatal asphyxia, infantile spasms, progressive encephalopathy-hypsarrhythmia-optical atrophy (PEHO) syndrome, infantile ceroid lipofuscinosis (INCL), autistic spectrum disorders (ASD) and subacute sclerosing encephalopathy (SSPE) have been carried out? What are IGF-based therapeutic strategies? What are the therapeutic approaches? We conclude that there are now great hopes for the therapeutic use of IGF-1 for some neurological disorders (particularly ASD).

Neural activity in the prelimbic and infralimbic cortices of freely moving rats during social interaction: Effect of isolation rearing

Sociability promotes a sound daily life for individuals. Reduced sociability is a central symptom of various neuropsychiatric disorders, and yet the neural mechanisms underlying reduced sociability remain unclear. The prelimbic cortex (PL) and infralimbic cortex (IL) have been suggested to play an important role in the neural mechanisms underlying sociability because isolation rearing in rats results in impairment of social behavior and structural changes in the PL and IL. One possible mechanism underlying reduced sociability involves dysfunction of the PL and IL. We made a wireless telemetry system to record multiunit activity in the PL and IL of pairs of freely moving rats during social interaction and examined the influence of isolation rearing on this activity. In group-reared rats, PL neurons increased firing when the rat showed approaching behavior and also contact behavior, especially when the rat attacked the partner. Conversely, IL neurons increased firing when the rat exhibited leaving behavior, especially when the partner left on its own accord. In social interaction, the PL may be involved in active actions toward others, whereas the IL may be involved in passive relief from cautionary subjects. Isolation rearing altered social behavior and neural activity. Isolation-reared rats showed an increased frequency and decreased duration of contact behavior. The increased firing of PL neurons during approaching and contact behavior, observed in group-reared rats, was preserved in isolation-reared rats, whereas the increased firing of IL neurons during leaving behavior, observed in group-reared rats, was suppressed in isolation-reared rats. This result indicates that isolation rearing differentially alters neural activity in the PL and IL during social behavior. The differential influence of isolation rearing on neural activity in the PL and IL may be one of the neural bases of isolation rearing-induced behavior.

Associated Medical Disorders and Disabilities in Children with Autistic Disorder

A population-based survey was conducted among 152,732 Finnish children and adolescents aged under 16 years and living in northern Finland. Diagnoses and associated medical conditions were derived from the hospital and institutional records of this area. One hundred and eighty-seven children with DSM-IV autistic disorder were identified. Associated medical disorders or associated disorders of known or suspected genetic origin were found in 12.3 percent, including tuberous sclerosis, Down syndrome, fragile X syndrome, Klinefelter syndrome, XYY syndrome, chromosome 17 deletion, chromosome 46, XX, dup(8)(p) and mitochondriopathy. Other associated medical disorders identified were epilepsy, hydrocephalus, foetal alcohol syndrome and cerebral palsy. Hearing impairments were found in 8.6 percent and severe impairment of vision in 3.7 percent of the individuals with autistic disorder. Medical disorders seem to have a special impact on the genesis of autistic disorder and need to be thoroughly examined in each child with autistic disorder.

The Neurodevelopmental Impact of Prenatal Infections at Different Times of Pregnancy: The Earlier the Worse?

Environmental insults taking place in early brain development may have long-lasting consequences for adult brain functioning. There is a large body of epidemiological data linking maternal infections during pregnancy to a higher incidence of psychiatric disorders with a presumed neurodevelopmental origin in the offspring, including schizophrenia and autism. Although specific gestational windows may be associated with a differing vulnerability to infection-mediated disturbances in normal brain development, it still remains debatable whether and/or why certain gestation periods may confer maximal risk for neurodevelopmental disturbances following the prenatal exposure to infectious events. In this review, the authors integrate both epidemiological and experimental findings supporting the hypothesis that infection-associated immunological events in early fetal life may have a stronger neurodevelopmental impact compared to late pregnancy infections. This is because infections in early gestation may not only interfere with fundamental neurodevelopmental events such as cell proliferation and differentiation, but it may also predispose the developing nervous system to additional failures in subsequent cell migration, target selection, and synapse maturation, eventually leading to multiple brain and behavioral abnormalities in the adult offspring. The temporal dependency of the epidemiological link between maternal infections during pregnancy and a higher risk for brain disorders in the offspring may thus be explained by specific spatiotemporal events in the course of fetal brain development. NEUROSCIENTIST 13(3):241—256, 2007.

Neuromotor Assessment and Autistic Disorder

Autistic disorder presents in early childhood with marked deviations in social interactions and communication and with a restricted and peculiar range of interests and activities. Although probably a heterogeneous condition, autistic disorder includes a class of individuals who also have subtle neurological impediments manifested as disturbances of movement, balance, posture and gait. We review neuromotor and neurobehavioral assessments for persons with autistic disorder and related conditions to improve the classification of the impairments and to facilitate the utilization of therapies specific for each class.

Is Autism Partly a Consolidation Disorder?

Computational modeling has been useful for understanding processes of encoding and consolidation in cortical structures. In particular, this work suggests a role of neuromodulators in setting dynamics for consolidation processes during different stages of waking and sleep. Because autistic individuals show symptoms of a cognitive nature coupled with a high prevalence of comorbid conditions such as epileptiform discharge during sleep and sleep disorders, it is possible that autism could involve a breakdown in consolidation processes, which are essential to build effective cognitive representations of the environment on the basis of individual experiences. In this article, theories of consolidation during different stages of waking and sleep and the role of different neuromodulators in these consolidation processes are reviewed in conjunction with different features of autism, which may be understood in the context of these theories.

A Short Review on the Current Understanding of Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a set of neurodevelopmental disorders characterized by a deficit in social behaviors and nonverbal interactions such as reduced eye contact, facial expression, and body gestures in the first 3 years of life. It is not a single disorder, and it is broadly considered to be a multi-factorial disorder resulting from genetic and non-genetic risk factors and their interaction. Genetic studies of ASD have identified mutations that interfere with typical neurodevelopment in utero through childhood. These complexes of genes have been involved in synaptogenesis and axon motility. Recent developments in neuroimaging studies have provided many important insights into the pathological changes that occur in the brain of patients with ASD in vivo. Especially, the role of amygdala, a major component of the limbic system and the affective loop of the cortico-striatothalamo-cortical circuit, in cognition and ASD has been proved in numerous neuropathological and neuroimaging studies. Besides the amygdala, the nucleus accumbens is also considered as the key structure which is related with the social reward response in ASD. Although educational and behavioral treatments have been the mainstay of the management of ASD, pharmacological and interventional treatments have also shown some benefit in subjects with ASD. Also, there have been reports about few patients who experienced improvement after deep brain stimulation, one of the interventional treatments. The key architecture of ASD development which could be a target for treatment is still an uncharted territory. Further work is needed to broaden the horizons on the understanding of ASD.

Assessment of a Long-Term Developmental Relationship-Based Approach in Children with Autism Spectrum Disorder

90 Italian children (72 boys, 18 girls) with a diagnosis of infantile autism (age range = 2.5–16.5 yr.) were assessed with a non-verbal intelligence test (Leiter–R). The test was repeated 3 times in four years. The measures used were IQ and Fluid Reasoning (FR), as evaluation of inductive and deductive reasoning, and the Autism Diagnostic Observation Schedule (ADOS), indicative of the severity of autistic symptoms at the beginning and at the end of therapy. The increase in the average IQ and FR scores at retests demonstrates the effectiveness of a treatment that emphasizes the centrality of the relationship-based approach. Moreover, the FR score at intake was predictive of a significant decrease of ADOS scores after four years of treatment, and of the increase in IQ observed in later evaluations. The data support the hypothesis that a relationship-based intervention allows cognitive improvement regardless of the autism severity expressed in the ADOS score.

Autism and EMF? Plausibility of a pathophysiological link - Part I

Although autism spectrum conditions (ASCs) are defined behaviorally, they also involve multileveled disturbances of underlying biology that find striking parallels in the physiological impacts of electromagnetic frequency and radiofrequency exposures (EMF/RFR). Part I of this paper will review the critical contributions pathophysiology may make to the etiology, pathogenesis and ongoing generation of core features of ASCs. We will review pathophysiological damage to core cellular processes that are associated both with ASCs and with biological effects of EMF/RFR exposures that contribute to chronically disrupted homeostasis. Many studies of people with ASCs have identified oxidative stress and evidence of free radical damage, cellular stress proteins, and deficiencies of antioxidants such as glutathione. Elevated intracellular calcium in ASCs may be due to genetics or may be downstream of inflammation or environmental exposures. Cell membrane lipids may be peroxidized, mitochondria may be dysfunctional, and various kinds of immune system disturbances are common. Brain oxidative stress and inflammation as well as measures consistent with blood-brain barrier and brain perfusion compromise have been documented. Part II of this paper will review how behaviors in ASCs may emerge from alterations of electrophysiological oscillatory synchronization, how EMF/RFR could contribute to these by de-tuning the organism, and policy implications of these vulnerabilities. Changes in brain and autonomic nervous system electrophysiological function and sensory processing predominate, seizures are common, and sleep disruption is close to universal. All of these phenomena also occur with EMF/RFR exposure that can add to system overload ('allostatic load') in ASCs by increasing risk, and worsening challenging biological problems and symptoms; conversely, reducing exposure might ameliorate symptoms of ASCs by reducing obstruction of physiological repair. Various vital but vulnerable mechanisms such as calcium channels may be disrupted by environmental agents, various genes associated with autism or the interaction of both. With dramatic increases in reported ASCs that are coincident in time with the deployment of wireless technologies, we need aggressive investigation of potential ASC - EMF/RFR links. The evidence is sufficient to warrant new public exposure standards benchmarked to low-intensity (non-thermal) exposure levels now known to be biologically disruptive, and strong, interim precautionary practices are advocated.

Clinical characteristics of children with autism spectrum disorder and co-occurring epilepsy

Objectives

To estimate the prevalence of epilepsy in children with Autism Spectrum Disorder (ASD) and to determine the demographic and clinical characteristics of children with ASD and epilepsy in a large patient population.

Methods

Cross-sectional study using four samples of children with ASD for a total of 5,815 participants with ASD. The prevalence of epilepsy was estimated from a population-based sample. Children with and without epilepsy were compared on demographic and clinical characteristics. Multivariate logistic regression was used to examine the association between demographic and clinical characteristics and epilepsy.

Results

The average prevalence of epilepsy in children with ASD 2–17 years was 12.5%; among children aged 13 years and older, 26% had epilepsy. Epilepsy was associated with older age, lower cognitive ability, poorer adaptive and language functioning, a history of developmental regression and more severe ASD symptoms. The association between epilepsy and the majority of these characteristics appears to be driven by the lower IQ of participants with epilepsy. In a multivariate regression model, only age and cognitive ability were independently associated with epilepsy. Children age 10 or older had 2.35 times the odds of being diagnosed with epilepsy (p<.001) and for a one standard deviation increase in IQ, the odds of having epilepsy decreased by 47% (p<.001).

Conclusion

This is among the largest studies to date of patients with ASD and co-occurring epilepsy. Based on a representative sample of children with ASD, the average prevalence of epilepsy is approximately 12% and reaches 26% by adolescence. Independent associations were found between epilepsy and older age and lower cognitive ability. Other risk factors, such as poor language and developmental regression, are not associated with epilepsy after controlling for IQ. These findings can help guide prognosis and alert clinicians to patients with ASD who are at increased risk for epilepsy.

Circuit level defects in the developing neocortex of Fragile X mice

Subtle alterations in how cortical network dynamics are modulated by different behavioral states could disrupt normal brain function and underlie symptoms of neuropsychiatric disorders, including Fragile X syndrome (FXS). Using two-photon calcium imaging and electrophysiology, we recorded spontaneous neuronal ensemble activity in mouse somatosensory cortex. Unanesthetized Fmr1(-/-) mice exhibited abnormally high synchrony of neocortical network activity, especially during the first two postnatal weeks. Neuronal firing rates were threefold higher in Fmr1(-/-) mice than in wild-type mice during whole-cell recordings manifesting Up/Down states (slow-wave sleep, quiet wakefulness), probably as a result of a higher firing probability during Up states. Combined electroencephalography and calcium imaging experiments confirmed that neurons in mutant mice had abnormally high firing and synchrony during sleep. We conclude that cortical networks in FXS are hyperexcitable in a brain state-dependent manner during a critical period for experience-dependent plasticity. These state-dependent network defects could explain the intellectual, sleep and sensory integration dysfunctions associated with FXS.

The neuropathology of autism

Autism is a behaviorally defined neurodevelopmental disorder that affects over 1% of new births in the United States and about 2% of boys. The etiologies are unknown and they are genetically complex. There may be epigenetic effects, environmental influences, and other factors that contribute to the mechanisms and affected neural pathway(s). The underlying neuropathology of the disorder has been evolving in the literature to include specific brain areas in the cerebellum, limbic system, and cortex. Part(s) of structures appear to be affected most rather than the entire structure, for example, select nuclei of the amygdala, the fusiform face area, and so forth. Altered cortical organization characterized by more frequent and narrower minicolumns and early overgrowth of the frontal portion of the brain, affects connectivity. Abnormalities include cytoarchitectonic laminar differences, excess white matter neurons, decreased numbers of GABAergic cerebellar Purkinje cells, and other events that can be traced developmentally and cause anomalies in circuitry. Problems with neurotransmission are evident by recent receptor and binding site studies especially in the inhibitory GABA system likely contributing to an imbalance of excitatory/inhibitory transmission. As postmortem findings are related to core behavior symptoms, and technology improves, researchers are gaining a much better perspective of contributing factors to the disorder.

A potential pathogenic role of oxalate in autism

BACKGROUND

Although autistic spectrum disorders (ASD) are a strongly genetic condition certain metabolic disturbances may contribute to clinical features. Metabolism of oxalate in children with ASD has not yet been studied.

AIM

The objective was to determine oxalate levels in plasma and urine in autistic children in relation to other urinary parameters.

METHOD

In this cross-sectional study, plasma oxalate (using enzymatic method with oxalate oxidase) and spontaneous urinary calcium oxalate (CaOx) crystallization (based on the Bonn-Risk-Index, BRI) were determined in 36 children and adolescents with ASD (26 boys, 10 girls) aged 2-18 years and compared with 60 healthy non-autistic children matched by age, gender and anthropometric traits.

RESULTS

Children with ASD demonstrated 3-fold greater plasma oxalate levels [5.60 (5th-95th percentile: 3.47-7.51)] compared with reference [(1.84 (5th-95th percentile: 0.50-4.70) μmol/L (p < 0.05)] and 2.5-fold greater urinary oxalate concentrations (p < 0.05). No differences between the two groups were found in urinary pH, citraturia, calciuria or adjusted CaOx crystallization rates based on BRI. Despite significant hyperoxaluria no evidence of kidney stone disease or lithogenic risk was observed in these individuals.

CONCLUSIONS

Hyperoxalemia and hyperoxaluria may be involved in the pathogenesis of ASD in children. Whether this is a result of impaired renal excretion or an extensive intestinal absorption, or both, or whether Ox may cross the blood brain barrier and disturb CNS function in the autistic children remains unclear. This appears to be the first report of plasma and urinary oxalate in childhood autism.

Noradrenergic moderation of working memory impairments in adults with autism spectrum disorder

In addition to having difficulties with social communications, individuals with an autism spectrum disorder (ASD) often also experience impairment in higher-order, executive skills. The present study examined the effects of pharmacological modulation of the norepinephrine system on the severity of such impairments. A sample of 14 high-functioning adults with ASD and a demographically-matched comparison group of 13 typically developing individuals participated. An AX continuous performance test (AX-CPT) was used to evaluate working memory and inhibitory control. AX-CPT performance was assessed following administration of a single dose of propranolol (a beta adrenergic antagonist) and following placebo (sugar pill) administration. Individuals with ASD performed more poorly than non-ASD individuals in the working memory condition (BX trials). Importantly, administration of propranolol attenuated this impairment, with the ASD group performing significantly better in the propranolol condition than the placebo condition. Working memory performance of the non-ASD group was unaffected by propranolol/placebo administration. No group or medication effects were observed for the inhibition condition (AY trials). The present findings suggest that norepinephrine may play a role in some, but not necessarily all, cognitive impairments associated with ASD. Additional research is needed to fully understand whether this role is primarily causal or compensatory in nature.

Plasma antioxidant capacity is reduced in Asperger syndrome

Recent evidence suggests that children with autism have impaired detoxification capacity and may suffer from chronic oxidative stress. To our knowledge, there has been no study focusing on oxidative metabolism specifically in Asperger syndrome (a milder form of autism) or comparing this metabolism with other psychiatric disorders. In this study, total antioxidant status (TAOS), non-enzymatic (glutathione and homocysteine) and enzymatic (catalase, superoxide dismutase, and glutathione peroxidase) antioxidants, and lipid peroxidation were measured in plasma or erythrocyte lysates in a group of adolescent patients with Asperger syndrome, a group of adolescents with a first episode of psychosis, and a group of healthy controls at baseline and at 8-12 weeks. TAOS was also analyzed at 1 year. TAOS was reduced in Asperger individuals compared with healthy controls and psychosis patients, after covarying by age and antipsychotic treatment. This reduced antioxidant capacity did not depend on any of the individual antioxidant variables measured. Psychosis patients had increased homocysteine levels in plasma and decreased copper and ceruloplasmin at baseline. In conclusion, Asperger patients seem to have chronic low detoxifying capacity. No impaired detoxifying capacity was found in the first-episode psychosis group in the first year of illness.

Auditory temporal-envelope processing in high-functioning children with Autism Spectrum Disorder

Individuals with Autism Spectrum Disorder (ASD) perform worse than controls when listening to speech in a temporally modulated noise (Alcántara, Weisblatt, Moore, & Bolton, 2004; Groen et al., 2009). The current study examined whether this is due to poor auditory temporal-envelope processing. Temporal modulation transfer functions were measured in 6 high-functioning children with ASD and 6 control listeners, using sinusoidal amplitude modulation of a broadband noise. Modulation-depth thresholds at low modulation rates were significantly higher for the ASD group than for the Control group, and generally higher at all modulation rates tested. Low-pass filter model estimates of temporal-envelope resolution and temporal-processing efficiency showed significant differences between the groups for modulation-depth threshold values at low modulation rates. Intensity increment-detection thresholds, measured on a subset of individuals in the ASD and Control groups, were not significantly different. The results are consistent with ASD individuals having reduced processing efficiency of temporal modulations. Possible neural mechanisms that might underlie these findings are discussed.

Autism in Early Childhood: An Unusual Developmental Course—Three Case Reports

Autistic spectrum disorder (ASD) is typically characterized by either an emerging and gradual course or developmental regression in early childhood. The versatile clinical course is progressively acknowledged in recent years. Children with developmental disorders in general are referred to the Child Development Center for a multidisciplinary assessment, investigation, treatment and followup. We report three infants with an initial diagnosis of developmental delays, recovery of normal development following intervention in a multidisciplinary center, and subsequent regression into classic autism following their discharge from the program. An extensive medical workup was noncontributory. This unusual presentation, to our knowledge not reported previously, should be recognized by professionals involved in child development and psychiatry.

Detecting abnormalities of corpus callosum connectivity in autism using magnetic resonance imaging and diffusion tensor tractography

The corpus callosum (CC) has emerged as one of the primary targets of autism research. To detect aberrant CC interhemispheric connectivity in autism, we performed T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI)-based tractography in 18 children with high functioning autism (HFA) and 16 well-matched typically developing (TD) children. We compared global and regional T1 measures (CC volume, and CC density), and the DTI measures [fractional anisotropy (FA), apparent diffusion coefficient (ADC), average fiber length (AFL), and fiber number (FN)] of transcallosal fibers, between the two groups. We also evaluated the relationships between scores on the Childhood Autism Rating Scale (CARS) and CC T1 or DTI measurements. Significantly less white matter density in the anterior third of the CC, and higher ADC and lower FN values of the anterior third transcallosal fiber tracts were found in HFA patients compared to TD children. These results suggested that the anterior third CC density and transcallosal fiber connectivity were affected in HFA children.

Do aluminum vaccine adjuvants contribute to the rising prevalence of autism?

Autism spectrum disorders (ASD) are serious multisystem developmental disorders and an urgent global public health concern. Dysfunctional immunity and impaired brain function are core deficits in ASD. Aluminum (Al), the most commonly used vaccine adjuvant, is a demonstrated neurotoxin and a strong immune stimulator. Hence, adjuvant Al has the potential to induce neuroimmune disorders. When assessing adjuvant toxicity in children, two key points ought to be considered: (i) children should not be viewed as "small adults" as their unique physiology makes them much more vulnerable to toxic insults; and (ii) if exposure to Al from only few vaccines can lead to cognitive impairment and autoimmunity in adults, is it unreasonable to question whether the current pediatric schedules, often containing 18 Al adjuvanted vaccines, are safe for children? By applying Hill's criteria for establishing causality between exposure and outcome we investigated whether exposure to Al from vaccines could be contributing to the rise in ASD prevalence in the Western world. Our results show that: (i) children from countries with the highest ASD prevalence appear to have the highest exposure to Al from vaccines; (ii) the increase in exposure to Al adjuvants significantly correlates with the increase in ASD prevalence in the United States observed over the last two decades (Pearson r=0.92, p<0.0001); and (iii) a significant correlation exists between the amounts of Al administered to preschool children and the current prevalence of ASD in seven Western countries, particularly at 3-4 months of age (Pearson r=0.89-0.94, p=0.0018-0.0248). The application of the Hill's criteria to these data indicates that the correlation between Al in vaccines and ASD may be causal. Because children represent a fraction of the population most at risk for complications following exposure to Al, a more rigorous evaluation of Al adjuvant safety seems warranted.

Sleep and autism spectrum disorders

Sleep disorders are common in children with autism spectrum disorders and have a significant effect on daytime function and parental stress. The cornerstone of treatment is to establish the cause of the sleep concern, which is often multifactorial. Identifying and treating sleep disorders may result not only in more consolidated sleep, more rapid time to fall asleep, and avoidance of night waking but also favorably affect daytime behavior and parental stress. Targeting effective treatment strategies is dependent on understanding the underlying causes of sleep problems in children with Autism spectrum disorders, therefore further research is paramount.

Functional connectivity networks in the autistic and healthy brain assessed using Granger causality

In this study, we analyze brain connectivity based on Granger causality computed from magnetoencephalographic (MEG) activity obtained at the resting state in eight autistic and eight normal subjects along with measures of network connectivity derived from graph theory in an attempt to understand how communication in a human brain network is affected by autism. A connectivity matrix was computed for each subject individually and then group templates were estimated by averaging all matrices in each group. Furthermore, we performed classification of the subjects using support vector machines and Fisher's criterion to rank the features and identify the best subset for maximum separation of the groups. Our results show that a combined model based on connectivity matrices and graph theory measures can provide 87.5% accuracy in separating the two groups. These findings suggest that analysis of functional connectivity patterns may provide a valuable method for the early detection of autism.

Somatosensory and sensorimotor consequences associated with the heterozygous disruption of the autism candidate gene, Gabrb3

Autism spectrum disorder (ASD) is diagnosed based on three core features: impaired social interactions, deficits in communication and repetitive or restricted behavioral patterns. Against this backdrop, abnormal sensory processing receives little attention despite its prevalence and the impact it exerts on the core diagnostic features. Understanding the source of these sensory abnormalities is paramount to developing intervention strategies aimed at maximizing the coping ability of those with ASD. Consequently, we chose to examine whether sensory abnormalities were present in mice heterozygous for the Gabrb3 gene, a gene strongly associated with ASD. Mice were assessed for tactile and heat sensitivity, sensorimotor competence (accelerating rotarod task) and sensorimotor gating by prepulse inhibition of the acoustic startle reflex (PPI). All heterozygotes exhibited an increase in seizure susceptibility and similar reductions in Gabrb3 expression in the dorsal root ganglia, spinal cord, whole brain and amygdala. Interestingly, significant differences were noted between heterozygous variants in regards to tactile sensitivity, heat sensitivity, sensorimotor competence and PPI along with differences in Gabrb3 expression in the reticular thalamic nucleus and the bed nucleus of stria terminalis. These differences were influenced by the heterozygotes' gender and whether the Gabrb3 gene was of paternal or maternal origin. These results are not adequately explained by simple haploinsufficiency of Gabrb3, therefore, additional mechanisms are likely to be involved. In addition, this is the first report of the occurrence of tactile and heat hypersensitivity in an ASD mouse model, two features often associated with ASD.

Sleep behaviors and sleep quality in children with autism spectrum disorders

STUDY OBJECTIVES

(1) Compare sleep behaviors of children with autism spectrum disorders (ASD) with sleep behaviors of typically developing (TD) children using the Children's Sleep Habits Questionnaire (CSHQ); (2) compare sleep quality--defined as mean activity, sleep latency, number of awakenings, sleep efficiency and total sleep time--of the cohort of children with ASD and TD, as measured by 10 nights of actigraphy; and (3) estimate the prevalence of sleep disturbances in the ASD and TD cohorts.

DESIGN

Descriptive cross-sectional study.

SETTING

The Children's Hospital of Philadelphia.

PARTICIPANTS

Randomly selected children from the Regional Autism Center. The ASD cohort of 59 children, aged 4 to 10 years, (26 with autism, 21 with pervasive developmental disorder-not otherwise specified [PDD-NOS], and 12 with Asperger disorder) were compared with 40 TD control subjects.

MEASUREMENTS AND RESULTS

The CSHQ, sleep diaries, and 10 nights of actigraphy using the Sadeh algorithm of children with ASD and TD control subjects were compared. CSHQ showed 66.1% of parents of children with ASD (62.5% autism, 76.2% PDD-NOS, 58.3% Asperger disorder) and 45% of parents of the control subjects reported that their children had sleep problems. Actigraphic data showed that 66.7% of children with ASD (75% autism, 52.4% PDD-NOS, 75% Asperger disorder) and 45.9% of the control subjects had disturbed sleep.

CONCLUSIONS

The prevalence estimate of 45% for mild sleep disturbances in the TD cohort highlights pediatric sleep debt as a public health problem of concern. The prevalence estimate of 66% for moderate sleep disturbances in the ASD cohort underscores the significant sleep problems that the families of these children face. The predominant sleep disorders in the ASD cohort were behavioral insomnia sleep-onset type and insomnia due to PDD.

Corpus callosum volume in children with autism

The corpus callosum (CC) is the main commissure connecting the cerebral hemispheres. Previous evidence suggests the involvement of the CC in the pathophysiology of autism. However, most studies examined the mid-sagittal area and investigations applying novel methods are warranted. The goal of this investigation is to apply a volumetric method to examine the size of the CC in autism and to identify any association with clinical features. An MRI-based morphometric study of the total CC volume and its seven subdivisions was conducted and involved 22 children with autism (age range 8.1-12.7 years) and 23 healthy, age-matched controls. Reductions in the total volume of the CC and several of its subdivisions were found in the autism sample. Associations were observed between CC structures and clinical features including social deficits, repetitive behaviors, and sensory abnormalities. Volumetric alterations of the CC observed in this investigation are consistent with midsagittal area tracings of decreased CC size in autism. These findings support the aberrant connectivity hypothesis with possible decrease in interhemispheric communications.

Autism: research into causes and intervention

Autism spectrum conditions are neuro-developmental syndromes with strong heritability. Cognitive theories have had some success in explaining why the cluster of features should co-occur. Empathizing deficits have the potential to make sense of one triad of impairments (social difficulties, communication difficulties and imagining others' minds), and may have a brain basis in the amygdala and left medial frontal cortex. A strong systemizing drive may account for a distinct triad of strengths (good attention to detail, deep, narrow interests and islets of ability). The brain basis of systemizing is yet to be understood. Family genetics studies suggest that these same cognitive dimensions (reduced empathizing alongside a strong drive to systemize) may also characterize the 'broader phenotype' among first-degree relatives. Molecular genetic studies are underway and any candidate genes for autism will ultimately need to be tested in relation to the observed differences in the brain, cognition and behaviour. The ethics of genetic screening or gene therapy should be thought about well ahead of these becoming available, since there is by no means any consensus that these would be desirable given the wide range of phenotypic traits, not all of which are disabling. Future research will need to focus on evaluating the extent to which any form of intervention reduces the triad of impairments whilst supporting the triad of strengths.

Enhanced long-term microcircuit plasticity in the valproic Acid animal model of autism

A single intra-peritoneal injection of valproic acid (VPA) on embryonic day (ED) 11.5 to pregnant rats has been shown to produce severe autistic-like symptoms in the offspring. Previous studies showed that the microcircuitry is hyperreactive due to hyperconnectivity of glutamatergic synapses and hyperplastic due to over-expression of NMDA receptors. These changes were restricted to the dimensions of a minicolumn (<50 μm). In the present study, we explored whether Long Term Microcircuit Plasticity (LTMP) was altered in this animal model. We performed multi-neuron patch-clamp recordings on clusters of layer 5 pyramidal cells in somatosensory cortex brain slices (PN 12-15), mapped the connectivity and characterized the synaptic properties for connected neurons. Pipettes were then withdrawn and the slice was perfused with 100 μM sodium glutamate in artificial cerebrospinal fluid in the recording chamber for 12 h. When we re-patched the same cluster of neurons, we found enhanced LTMP only at inter-somatic distances beyond minicolumnar dimensions. These data suggest that hyperconnectivity is already near its peak within the dimensions of the minicolumn in the treated animals and that LTMP, which is normally restricted to within a minicolumn, spills over to drive hyperconnectivity across the dimensions of a minicolumn. This study provides further evidence to support the notion that the neocortex is highly plastic in response to new experiences in this animal model of autism.

The usefulness of the Revised Psychoeducational Profile for the assessment of preschool children with pervasive developmental disorders

Data from the Psychoeducational Profile—Revised (PEP—R) were analysed in a sample of 46 children, aged from 1.7 to 5.11 years, of whom 21 had autistic disorder (AD) and 25 had pervasive developmental disorder not otherwise specified (PDD-NOS). Analysis with a t-test for independent samples revealed a significant difference ( p < 0.05) between children with AD and those with PDD-NOS on both developmental and behavioural PEP—R scales, supporting the utility of the PEP—R in discriminating between two diagnostic groups. This study emphasizes the effectiveness of the PEP—R as a tool for the early assessment of children with pervasive developmental disorders.

Aberrant functional connectivity in autism: evidence from low-frequency BOLD signal fluctuations

A number of recent studies have examined functional connectivity in individuals with Autism Spectrum Disorders (ASD), generally converging on the finding of reduced interregional coordination, or underconnectivity. Underconnectivity has been reported between many brain regions and across a range of cognitive tasks, and has been proposed to underlie behavioral and cognitive impairments associated with ASD. The current study employed functional connectivity MRI (fcMRI) to examine interregional correlations of low-frequency BOLD signal fluctuations in 10 high-functioning participants with ASD and 10 typically developing control participants. Whole-brain connectivity with three seed regions of interest (left middle frontal, left superior parietal, and left middle occipital cortex) was evaluated using fMRI datasets acquired during performance of a source recognition task. While fcMRI patterns were found to be largely similar across the two groups, including many common areas, effects for the ASD group were generally more extensive. These findings, although inconsistent with generalized underconnectivity in ASD, are compatible with a model of aberrant connectivity in which the nature of connectivity disturbance (i.e., increased or reduced) may vary by region. Taking into consideration methodological factors that might influence measured fcMRI effects, we suggest that ASD is associated with an inefficiency in optimizing network connections to achieve task performance.

Secondary medical diagnosis in fragile X syndrome with and without autism spectrum disorder

This study examined whether secondary medical diagnoses that affect CNS function (i.e., seizures, malformations, or genetic disorders), are more likely to occur in individuals with fragile X syndrome (FXS) and autism spectrum disorder (FXS + ASD) or FXS alone. Ninety males (3-25 years) with FXS or FXS + ASD were evaluated for secondary medical diagnoses by medical history and examination. A significant difference in the incidence of medical problems was found between patients with FXS + ASD (38.6%) and FXS alone (18.2%, P < 0.05). Medical problems that affect the CNS are more likely to occur in those with FXS + ASD and it is probable that additional brain dysfunction associated with these medical problems enhance the risk of autism in those with FXS.

An investigation of sleep characteristics, EEG abnormalities and epilepsy in developmentally regressed and non-regressed children with autism

This study investigated sleep of children with autism and developmental regression and the possible relationship with epilepsy and epileptiform abnormalities. Participants were 104 children with autism (70 non-regressed, 34 regressed) and 162 typically developing children (TD). Results suggested that the regressed group had higher incidence of circadian rhythm disorders than non-regressed children. The regressed group showed higher Children's Sleep Habits Questionnaire Bedtime Resistance, Sleep Onset Delay, Sleep Duration and Night-Wakings scores. Epilepsy and frequent epileptiform EEG abnormalities were more frequent in regressed children. Past sleep disorders and a history of developmental regression were significantly associated with sleep disorders. This study is an initial step in better understanding sleep problems in regressed children with autism, further studies are necessary to better investigate these aspects.

Associative learning of pictures and words by low-functioning children with autism

This research investigates whether children with autism learn picture, word and object relations as associative pairs or whether they understand such relations as referential. In Experiment 1, children were taught a new word (e.g. `whisk') repeatedly paired with a novel picture. When given the picture and a previously unseen real whisk and asked to indicate a whisk, children with autism, unlike typically developing peers matched on receptive language, associated the word with the picture rather than the object. Subsequent experiments respectively confirmed that neither a bias for selecting pictures nor perseverative responding accounted for these results. Taken together, these results suggest that children with autism with cognitive difficulties are learning picture—word and picture—object relations via an associative mechanism and have difficulty understanding the symbolic nature of pictures.

Technetium-99m HMPAO brain SPECT in autistic children and their families

The purpose of the study was to investigate perfusion patterns in autistic children (AC) and their families. Ten AC (9 boys, 1 girl; mean age: 6.9+/-1.7 years) with autistic disorder defined by DSM-III-R criteria, five age-matched children (3 boys, 2 girls) as a control group, and the immediate family members of eight AC (8 mothers, 8 fathers, 7 siblings; mean ages: 39+/-4 years, 36+/-5 years and 13+/-5 years, respectively) were included in the study. Age- and sex-matched control groups for both the parents and the siblings were also included in the study. Brain perfusion images were obtained 1 h after the intravenous injection of an adjusted dose of Tc-99m HMPAO to children and the adults. Visual and semiquantitative evaluations were performed. Hypoperfusion was seen in the right posterior parietal cortex in three AC, in bilateral parietal cortex in one AC, bilateral frontal cortex in two AC, left parietal and temporal cortex in one AC, and right parietal and temporal cortex in one AC. Asymmetric perfusion was observed in the caudate nucleus in four AC. In semiquantitative analyses, statistically significant hypoperfusion was found in the right inferior and superior frontal, left superior frontal, right parietal, right mesial temporal and right caudate nucleus. In parents of AC, significant hypoperfusion was noted in the right parietal and bilateral inferior frontal cortex. In siblings of AC, perfusion in the right frontal cortex, right nucleus caudate and left parietal cortex was significantly decreased. This preliminary study suggests the existence of regional brain perfusion alterations in frontal, temporal, and parietal cortex and in caudate nucleus in AC and in their first-degree family members.

Growth-related neural reorganization and the autism phenotype: a test of the hypothesis that altered brain growth leads to altered connectivity

Theoretical considerations, and findings from computational modeling, comparative neuroanatomy and developmental neuroscience, motivate the hypothesis that a deviant brain growth trajectory will lead to deviant patterns of change in cortico-cortical connectivity. Differences in brain size during development will alter the relative cost and effectiveness of short- and long-distance connections, and should thus impact the growth and retention of connections. Reduced brain size should favor long-distance connectivity; brain overgrowth should favor short-distance connectivity; and inconsistent deviations from the normal growth trajectory - as occurs in autism - should result in potentially disruptive changes to established patterns of functional and physical connectivity during development. To explore this hypothesis, neural networks which modeled inter-hemispheric interaction were grown at the rate of either typically developing children or children with autism. The influence of the length of the inter-hemispheric connections was analyzed at multiple developmental time-points. The networks that modeled autistic growth were less affected by removal of the inter-hemispheric connections than those that modeled normal growth - indicating a reduced reliance on long-distance connections - for short response times, and this difference increased substantially at approximately 24 simulated months of age. The performance of the networks showed a corresponding decline during development. And direct analysis of the connection weights showed a parallel reduction in connectivity. These modeling results support the hypothesis that the deviant growth trajectory in autism spectrum disorders may lead to a disruption of established patterns of functional connectivity during development, with potentially negative behavioral consequences, and a subsequent reduction in physical connectivity. The results are discussed in relation to the growing body of evidence of reduced functional and structural connectivity in autism, and in relation to the behavioral phenotype, particularly the developmental aspects.

Autism spectrum disorders: concurrent clinical disorders

Individuals with autism spectrum disorder are heterogeneous in clinical presentation, concurrent disorders, and developmental outcomes. This study characterized the clinical co-occurrences and potential subgroups in 160 children with autism spectrum disorders who presented to The Autism Center between 1999 and 2003. Medical and psychiatric co-occurrences included sleep disorders, epilepsy, food intolerance, gastrointestinal dysfunction, mood disorder, and aggressive and self-injurious behaviors. Sleep disorders were associated with gastrointestinal dysfunction (P < .05) and mood disorders (P < .01). Food intolerance was associated with gastrointestinal dysfunction (P = .001). Subjects with mood disorder tended to develop aggressive or self-injurious behaviors (P < .05). Developmental regression was not associated with increased co-occurrence of medical or psychiatric disorders. Medical co-occurrence did not present as a risk factor for psychiatric co-occurrence, and vice versa. These results showed a high prevalence of multiple medical and psychiatric co-occurrences. There may be common pathophysiologic mechanisms resulting in clinical subgroups of autism spectrum disorders. Recognition of the co-occurrence of concurrent disorders may provide insight into the therapeutic strategy.