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October, 2012

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Atypical Astrocytes Found in Brains of ASD Patients

By Mark N. Ziats on October 26, 2012
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Background:

The brain is the main organ responsible for controlling the complex processes that govern human behavior. The brain contains both neurons—the cells responsible for transmitting chemical and electrical signals throughout the brain—and glia—a population of cells that provide various supporting roles in the brain. Until recently, very few studies focused on the role of glia in Autism Spectrum Disorder (ASD).

 

What’s new:

In a recent study published 21 September 2012 in the  Journal of Neuroinflammation, researchers found abnormalities in glial cells known as astrocytes in brains from autistic children. Using post-mortem brain tissue from six autistic patients and six age-matched controls, the researchers discovered that astrocytes from autistic brains were abnormal in size, shape, and number. Additionally, brains from a common mouse model of autism showed similar astrocyte defects. Upon further investigation, the researchers found that a molecular pathway thought to be involved in astrocyte development (called the Wnt/Β-catenin pathway) was decreased in the brain samples of autistic patients.

 

Why it’s important:

Both neurons and glia play an important role in the functioning brain.  By understanding how each cell type links to the core behaviors seen in autism and knowing which molecular pathways may be aberrant in those cells, researchers can better target effective therapies.  Both human and animal studies will play an important role towards this goal.


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Researchers Examine Newborn Immune System in ASD Risk

By Stacy W. Kish on October 26, 2012
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Background: Humans receive protection from their mothers (passive immunity) to resist infectious organisms before and shortly after birth. This protection, however, only protects the infant for several weeks. The baby’s immune system quickly activates after birth to begin defending the body from pathogens and resist infections. Previous work revealed that children and adults diagnosed with Autism Spectrum Disorder (ASD) had abnormal levels of immune molecules in their blood.

 

What’s new: A recent study published in the Journal of Neuroimmunology examined the blood samples of more than 300 newborns later diagnosed with autism and more than 700 control patients. The researchers measured the level of 16 cell signaling molecules, called cytokines, that contribute to the immune system. Their work showed that nine of the molecules were lower (in particular T helper 1 and T helper 2) in the autistic patients as newborns and adults compared to the controls. The samples were collected between 1982 and 2000 in Denmark.

 

Why it’s important: Previous work has shown that autistic patients have increased levels of certain circulating immune molecules known as cytokines. This study, however, is the first to show a decreased level of select cytokines. The discrepancy may be due to study complications, such as diagnostic inconsistencies or sample degradation. A mechanism that depresses immune function specifically in the newborn remains unclear.


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Amygdala Size, Repetitive Behaviors Linked to Immune Cells

By Shana R. Spindler, Ph.D. on October 24, 2012

 

Background: Previous research has shown that Autism Spectrum Disorder (ASD) correlates with abnormal activation and function of the innate immune system, a population of cells that provides an initial defense against foreign organisms. How innate immune system regulation is linked to ASD is an active area of investigation.

 

What’s New: Researchers at the MIND Institute (University of California, Davis) reported in the 17 October online edition of Brain, Behavior, and Immunity that dendritic cells—an important cell population within the innate immune system—are significantly increased in children with ASD. The researchers examined 57 children, ages 2-3 years, and 29 age-matched controls. For both groups, the researchers found a positive correlation between circulating dendritic cell number and size—as measured by MRI—of the amygdala, a brain structure involved in processing emotional events and memory. Additionally, the researchers report that children with ASD who have increased circulating dendritic cells also have more pronounced repetitive behaviors, according to ADOS assessment. For children with a regressive form of ASD, the researchers found a positive association with a specific sub-population of dendritic cells.

 

Why It’s Important: This is the first study to show a correlation between innate immune system regulation, structural changes in a brain region called the amygdala, and behavioral severity. Little is known about the mechanisms that link the immune system to ASD pathogenesis. This study supports the hypothesis that innate immune system dysfunction may affect the development and/or maintenance of brain structures that control behaviors associated with ASD.


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Computational Method May Aid Autism Diagnosis

By Chelsea E. Toledo, M.A. on October 23, 2012
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Background: Recent technological advances have the potential to improve how Autism Spectrum Disorders (ASD) are classified and diagnosed. Brain cells use energy when they communicate with each other, which results in increased blood flow to their local area to replenish their energy. Scientists use a technique called functional magnetic resonance imaging (fMRI) to measure these changes in blood flow, allowing them to infer which areas of the brain are active.. Computational approaches are then used to help find patterns of activated brain regions, allowing ASD patient brain activity patterns to be compared to those of neurotypical patients.

 

What’s new: In a study published in the October 2012 edition of the online journal PLoS ONE, researchers detail an emerging computational approach for analyzing fMRI data from 58 people—half of whom had an ASD diagnosis. They monitored the activity of 106 brain regions and found their method could distinguish ASD patients in >80% of the cases. Additionally, the researchers found that an ASD diagnosis could better be predicted at a fine scale rather than at a coarse scale (involving long-range connections between different brain regions) that researchers typically look at.

 

Why it’s important: Many scientists believe that ASD is associated with the way regions of the brain interact with one another, but few have been able to demonstrate concretely how those problems manifest. Better ways of analyzing brain images could lead to a better understanding of how ASD works—and how it can be remedied.


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Research Supports Additive Model of ASD Risk

By Stacy W. Kish on October 18, 2012
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Background: Autism Spectrum Disorder (ASD) is defined by impaired social interaction and communication, as well as repetitive behaviors. With new technologies developed during the past decade, scientists began looking for genetic variations to explain ASD.

 

What’s new: This study examined the genomes of 2,700 families with one (simplex) or several (multiplex) autistic children. The researchers used statistical models to determine the risk of autism resulting from the contribution of both common and rare genetic variations known as single nucleotide polymorphisms (SNPs). The results suggest that a delicate interplay occurs between the additive effect of many common variants and the risk of autism, dubbed the Additive model of ASD risk. For currently unknown reasons, simplex families follow the additive model more closely than multiplex families.

 

Why it’s important: This work contributes to the long-standing question in the scientific community on the extent of genetic contribution to ASD.  Future studies may further define the involvement of common and rare genetic variations in the risk of autism. In addition, this work may contribute to the development of diagnostic tests in the future to assess an individual’s risk of developing autism.


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New Autism Guidelines Catch Most Cases

By Chelsea E. Toledo, M.A. on October 17, 2012

 

Background: The Diagnostic and Statistical Manual of Mental Disorders (DSM), published by the American Psychiatric Association, provides criteria for identifying mental and behavioral syndromes. The current edition, DSM-IV, contains a three-domain model for diagnosing Autism Spectrum Disorder (ASD), based on criteria for social interaction, communication and behaviors. The newly proposed criteria for ASD, to be published in DSM-V, have two domains for diagnosis—social interaction and behavior, with communicative criteria now considered part of social interaction.

 

What’s New: Studies evaluating the new ASD criteria have been limited in discerning their sensitivity—how accurately they diagnose people with ASD—as well as their specificity—how well they distinguish between people with ASD and those with other disorders. In a report published in the American Journal of Psychiatry, researchers describe a new study of over 5,000 children evaluated by way of observations and interviews with their parents. The study reports that the DSM-V criteria for ASD were as sensitive and more specific than those in DSM-IV—resulting in correct diagnoses 91 percent of the time.

 

Why it’s important: Previous studies have suggested that the proposed criteria for ASD could exclude many people with Asperger syndrome or pervasive developmental disorder-not otherwise specified (PDD-NOS). Without diagnoses, people with ASD could lose access to care. However, the new guidelines catch most cases of both syndromes.


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AutRR Features New Conference Updates Page

By Shana R. Spindler, Ph.D. on October 16, 2012

 

AutRR News Brief: Scientists have gathered from around the world in New Orleans, LA to attend Neuroscience 2012, the 42nd annual meeting hosted by the Society for Neuroscience. The conference began on Saturday, 13 October and will continue through Wednesday, 17 October.

 

Researchers at the meeting will discuss new—sometimes unpublished—data on topics ranging from the details of neural excitability to broader concepts of cognition and behavior. Autism Reading Room will contain short conference updates about Autism Spectrum Disorder (ASD) research presented at the meeting.

 

A few highlights so far include information about ASD brain connectivity, differences in autonomic processing, and compromised energy production in ASD brain cells. To learn about these topics and more, please visit our Conference Updates page!


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Evidence for Impaired Social Learning in Autism

By Wayne Pereanu on October 12, 2012
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Background:

People learn how to behave in situations by associating their behaviors with rewards they receive when they are successful. Rewards can be external, like money or food, but can also be a pleasurable sensation produced by the brain. It is thought that humans learn to socially interact by being “rewarded” with pleasure during positive social encounters. A long-held theory suggests that ASD may be caused by impairments that reduce this pleasurable reward, leading to difficulty in acquiring social skills. It is currently unclear whether the reward processing deficiency is specifically impaired during only social situations.

 

What's new:

Researchers looked at the brain activity of 21 ASD patients using a technique known as fMRI. They asked ASD and control patients to perform tasks in which they could earn either monetary rewards (images of a coin) or social rewards (images of a happy face). They found that the ASD group had a significantly reduced response when given a social reward compared to the control group. However, no difference was found when monetary rewards were provided.

 

Why it's important:

The study provides direct evidence for a brain-based impairment in the “reward” system specific to social situations. Because social reward processing occurs in a distinct area of the brain, these results suggest potential areas of the brain where future work may focus.


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Specific Genetic Variations May Help Predict ASD

By Shana R. Spindler, Ph.D. and Mark Ziats on October 12, 2012
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Background: The diagnosis of Autism Spectrum Disorder (ASD) is currently based on clinical interviews. Doctors lack laboratory tests or other biomarkers to help support a diagnosis. Autism has a strong genetic component, but knowing which genetic variations contribute to or protect against autism is a major challenge for diagnosis.

 

What’s new: Scientists have developed a diagnostic test by mapping genetic variations into cellular pathways that might be affected in autism. A specific combination of 237 common genetic variations, called single nucleotide polymorphisms (SNPs), can predict an ASD diagnosis with at least 71 to 85 percent accuracy, according to a new study published 11 September in Molecular Psychiatry. The predictive accuracy, however, is only strong in those genetically similar to Central Europeans. The same SNPs predicted ASD with only 57 percent accuracy in a genetically dissimilar Chinese population. According to the authors, at least some of the genes harboring autism-linked SNPs are expressed in various brain regions implicated in ASD, and those genes are also important for cellular processes required for proper neuron functioning.

 

Why it’s important: An SNP profile may eventually become an important biomarker in the diagnosis of ASD. SNP testing during early infancy could allow detection of ASD before symptoms manifest, allowing for earlier therapeutic intervention, which may increase the success rate of therapy.

 


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Wandering is Common and Dangerous in Autistic Children

By Mark N. Ziats on October 11, 2012
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Background:  Anecdotal reports from parents with autistic children have suggested that wandering away from caregivers is a serious and potentially dangerous problem. However, no study has systematically assessed this issue in a large number of patients.

 

What’s new:  Using an online questionnaire of more than 1200 families with an autistic child, researchers discovered that almost half of autistic children had wandered away from home, and of those who wandered, half were gone for a long enough period to cause serious concern. This was significantly higher than their siblings without autism. Moreover, the autistic children were often in serious danger of drowning or traffic injury when they wandered off. Greater severity of autism was associated with a higher chance of wandering behavior.

 

Why it’s important:  This study provides the first rigorous assessment of this problem, allowing further studies to focus on effective means of preventing, intervening, and helping parents to cope with wandering behavior. It also serves to highlight the importance of this problem for childcare professionals, teachers, and others who may be involved with autistic children.


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Drug Corrects Brain Circuitry in Rett Syndrome Mice

By Ishita Das on October 10, 2012

 

Background: Rett syndrome (RTT) is characterized by severe cardiac and respiratory impairments, together with autistic symptoms. It is believed that the brainstem and spinal cord functions controlling heart rate and breathing are compromised partly by an underactive set of brain structures, known as the limbic system, which are responsible for maintaining an appropriate emotional state. An increased understanding of the neural circuitry that governs behavioral and emotional states is therefore needed.

 

What’s new: Treating an adult mouse model of RTT with the FDA approved drug ketamine can reverse sensorimotor functions typical of RTT as well as remedy an altered gene expression pattern in the mutant mice, according to a breakthrough study appearing online, 3 October 2012, in the Journal of Neuroscience.  Ketamine is a known inhibitor of NMDA receptors, which reduce excitation of neural circuits. Treatment with ketamine likely restores function by balancing neurotransmission.

 

Why it’s important: RTT occurs with an incidence of 1 in 10,000 females, in which 26% of deaths are sudden and of unknown cause. Cardiac arrhythmias and respiratory failure are considered to be at least partially responsible in some of these fatalities. Ketamine emerges as a strong candidate drug to improve physiological and neural functioning in RTT with important treatment implications for autism, which is rooted in imbalanced neurotransmission.

 


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Researchers Study Eye Tracking in Natural Environment

By Stacy W. Kish on October 9, 2012
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Background: One characteristic of Autism Spectrum Disorder (ASD) is the avoidance of making or maintaining eye contact. Instead, autistic children tend to focus on they eyebrows, mouth, or other facial features. Scientists hypothesize that avoiding eye contact narrows the development of the social brain network.

 

What’s new: Unlike previous studies set in a clinical setting, this study examined the gaze of autistic and typically developing children in a natural environment. Each child wore a device to monitor their gaze as s/he responded to and engaged in normal forms of play. During these interactions, the researchers measured the direction of gaze and the child’s field of vision. The autistic children in the study avoided the face of the experimenter more than children in the control group did. The autistic children also used their lateral field of view and looked downward more than the control group.

 

Why it’s important: Researchers study the gaze of autistic children to understand how the disorder affects child development. Studies in a natural setting are rare, and this work provides a unique perspective in this area of research.  Future work could build on these findings by studying how head motion and focus on non-social stimuli could lead to development of novel diagnostic tools

 


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NIH Grant Establishes Atlanta Autism Center of Excellence

By Stacy W. Kish on October 5, 2012

 

Background: Autism affects an estimated 1 in 88 children nationwide. The disorder is characterized by impaired social and communication skills. Currently, scientists can diagnose autism in children as young as two years of age. Although scientists do not have a firm grasp of what causes autism, they have linked the disorder to variations in brain biology.

 

What’s new: The National Institutes of Health awarded scientific grants to research institutes in Atlanta, Los Angeles, and Boston. In Atlanta, the funds will be used to develop the Autism Center of Excellence. The Atlanta Center will coordinate local research institutes and hospital resources in this effort.

 

Why it’s important: This funding will allow scientists to explore new tools to diagnose and treat the disorder. In Atlanta, scientists will apply the federal grant money to four projects focused on social and vocal engagement, early treatment, and brain functioning. The results of this work will develop routine processes to help pediatricians around the country diagnose autism in children at an earlier age.


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Rett Syndrome-Linked Gene Needed for Synapse Stability

By Shana R. Spindler, Ph.D. on October 4, 2012
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Background: Rett syndrome (RTT) is a genetic disorder marked by developmental regression after 6 to 18 months of age. RTT, which is almost exclusively seen in girls, is currently classified as an Autism Spectrum Disorder (ASD). Most RTT cases are caused by mutations in the MECP2 gene. Some atypical forms of RTT do exist, including those caused by variations in the CDKL5 gene. Both MECP2 and CDKL5 contribute to neuron maturation, but exactly how CDKL5 is linked to RTT symptoms is unclear.

 

What’s New: Researchers have uncovered a series of events that indicate an important role for CDKL5 in the stability of synapses, sites where two neurons meet to transmit electric or chemical signals. According to a new study published in the September 2012 issue of Nature Cell Biology, CDKL5 is important for the density and shape of dendritic spines, small protrusions on a neuron that harbor a synapse and receive neural signals.

 

Why it’s important: Studies like this help piece together how variations in different genes can lead to the same syndrome. As doctors and researchers work to develop targeted therapies for disorders within the autism spectrum, it will be important to understand how each individual’s genetic variations affect the development and function of his or her brain.


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The Additive Effects of CNVs on ASD Outcome

By Eric C. Larsen, Ph.D. on October 3, 2012

 

Background:  The gains or losses of large chunks of DNA, collectively known as copy number variants (CNVs), have in recent years come under increased scrutiny as potential causative factors in human disease.  While a number of CNVs at particular locations in the human genome are strongly associated with neurodevelopmental disorders such as Autism Spectrum Disorder (ASD), affected individuals who carry these CNVs display differences both in the type of disease that they have and in the severity of disease, a phenomenon known as phenotypic heterogeneity.  Understanding the basis of such phenotypic heterogeneity is critical in being able to correctly interpret the results of genetic screening.

 

What’s new:  In a recent report in the New England Journal of Medicine, researchers screened 2312 children known to carry a CNV associated with neurodevelopmental disorders and congenital anomalies for additional CNVs.  The researchers determined that, in addition to the primary CNV, approximately 10% of affected children carried a second large CNV.  Not only were affected children more likely to carry multiple CNVs than controls, affected children with more than one CNV tended to display more severe symptoms.

 

Why it’s important:  These findings lend further credence to what the authors of the report refer to as the “two-hit” or second-site model, which suggests that the phenotypic heterogeneity observed in patients with ASD and other neurodevelopmental disorders results from the additive effects of multiple rare genetics variants, such as CNVs.


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New Autism Study Recruiting Newborns

By Chelsea Toledo, M.A. on October 2, 2012

 

Background: Autism Spectrum Disorder (ASD) is typically diagnosed in early childhood. The rates of diagnosis have increased in recent years—from 2006 to 2008 its prevalence increased by 23 percent, with 1 in 88 children being diagnosed in the United States. Studies have shown that ASD is more commonly diagnosed in boys, and that 20 percent of children with ASD will have a sibling with the disorder.

 

What’s New: The National Institutes of Health have awarded a 5 year, $2.2 million grant to The Center for Autism Research at the Children's Hospital of Philadelphia (CHOP) for a study on children starting at 3 months old. The researchers are currently recruiting expecting parents and parents of newborns with or without a family history of ASD. Using magnetic resonance imaging (MRI), they aim to pinpoint early signs of ASD by observing changes in the children's brains from infancy to 5 years of age.

 

Why it’s important: Earlier research at CHOP demonstrated that autistic children's brains develop differently than those of children without the disorder. These internal differences emerge before the disorder becomes externally apparent. Children who receive timely interventions for autism have better life outcomes, so understanding the early changes in the brain could lead to quicker diagnosis and more effective therapy.


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