Data Processing And Analysis
All statistical analyses were performed using SPSS 6.1.1 software . Independent sample t-tests were used to compare structure sizes between the autistic and control subjects as well as for post hoc analysis. Either separate or pooled variance analyses were used, as indicated by Levene’s test for equality of variances. One-tailed tests were used in the initial between-group comparisons based on the hypothesis that frontal lobe tissue volume would be larger in autistic patients, while lobule VIVII area would be smaller. Linear regression analysis was used to test for possible relationships between the size of lobules VIVII and the volume of the frontal lobe cortex in each subject group. Since autism, and perhaps even normal development, may involve some significant degree of biological heterogeneity, these analyses did not include statistically identified outliers. In order to identify such subjects, linear regression analyses were performed first, with all subjects from the group included. The standardized residuals were then used to identify outliers and the analyses were repeated with outliers removed on an analysis-by-analysis basis. That is, for any given comparison any subject with a standardized residual more than 2 standard deviations from the mean on the initial comparison was removed and the analysis was repeated. Three autistic patients and one normal control were identified and excluded by this process.
What Does Autism Do To The Brain
Much like a computer, the brain relies on intricate wiring to process and transmit information. Scientists have discovered that, in people with autism, there is a misfiring in communication between brain cells.
So what does autism do to the brain, exactly?In the brain, nerve cells transmit important messages that regulate body functionseverything from social behavior to movement. Imaging studies have revealed that autistic children have too many nerve fibers, but that theyre not working well enough to facilitate communication between the various parts of the brain.
Scientists think that all of this extra circuitry may affect brain size. Although autistic children are born with normal or smaller-than-normal brains, they undergo a period of rapid growth between ages 6 and 14 months, so that by about age four, their brains tends to be unusually large for their age. Genetic defects in brain growth factors may lead to this abnormal brain development.
Scientists also have discovered irregularities in the brain structures themselves, such as in the corpus callosum , amygdala , and cerebellum . They believe these abnormalities occur during prenatal development.
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Big Brains: An Autism Subtype
In the first study, published in Biological Psychiatry, the researchers used magnetic resonance imaging to track brain size in 294 children with autism and 135 children without autism between the ages of 3 and 12. In children with autism, they found evidence of larger brain size relative to height – or disproportionate megalencephaly – a subtype that has been linked to higher rates of intellectual disability and poorer overall prognosis.
Previous cross-sectional research had found that children with autism have larger brains at early ages, but no evidence of larger brains in later childhood. The widely accepted theory is that these brains normalized or shrank as the children grew up.
The MIND Institute study found that wasnt the case. The children who had bigger brains at age 3 still had bigger brains at age 12. Why? Unlike most research, which studies different individuals at different time points, this research studied the same children longitudinally, or over time.
Also, unlike most other studies, this one includes children with significant intellectual disabilities. These were the children who tended to have the big brain form of autism.
David Amaral, co-senior author on both studies, suggested that the difference between this and previous research was that children with intellectual disability were left out of previous cross-sectional studies focused on older children.
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Autism In The Brain Region By Region
If the brain were a house with many rooms, you wouldnt find autism in just one of them. Autism has many causes and many forms. But no matter which form it takes, it seems to touch the entire brain. It permeates and perturbs the beams, foundation, wiring and piping of the house, rather than just, say, the kitchen.
Still, autism does have local effects: Different regions of the brain contribute uniquely to autisms impact on cognition, emotion and behavior.
In this special report, we detail the regional consequences of autism, one brain area at a time. Studies of the hippocampus, for example, may help explain the uneven effects of autism on memory. Investigations of the superior temporal sulcus may provide a window into the impact of autism on social perception.
The report is ongoing. Over time, our reporters will step into the various rooms of the brain to probe autisms effect on those regions.
Diagnostic Models Based On Imaging Genetics
Imaging genetics in ASD has proven useful, and pathways that include common genetic variation in TD individuals at risk of developing ASD have been characterized. Prenatal transcription regulation and synapse formation in the developing brain is impacted by the genes associated with ASD . Alteration in frontal WM connectivity and structure and disturbance in the frontal, temporal, and occipital circuits involved in visual and language processing was found to be associated with NRXN superfamily genes. Neuropeptide signaling and emotional functioning was found to be influenced by the oxytocin and arginine vasopressin receptor genes via structural and functional modification in the amygdalahypothalamus circuitry. One study showed a relationship between frontal lobe connectivity and common genetic variants in CNTNAP2 using a functional neuroimaging study and the study found that ASD and TD individuals who were nonrisk allele carriers showed more reduction in the activation of mPFC during an fMRI task as compared to risk allele carriers. Another study showed decreased functional connectivity in the prefrontal cortex, cortical spinal tract, corpus callosum, and decreased integrity of WM in children and adolescents carrying MET rs1858830, C risk allele. Such studies suggest that the genes affect the brain regions that are involved in social and emotional processing.
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Learning Social Issues May Reflect Neuronal Miscommunication
- Washington University School of Medicine
- Mutations in a gene linked to autism in people causes neurons to form too many connections in rodents, according to a new study. The findings suggest that malfunctions in communication between brain cells could be at the root of autism.
A defective gene linked to autism influences how neurons connect and communicate with each other in the brain, according to a study from Washington University School of Medicine in St. Louis. Rodents that lack the gene form too many connections between brain neurons and have difficulty learning.
The findings, published Nov. 2 in Nature Communications, suggest that some of the diverse symptoms of autism may stem from a malfunction in communication among cells in the brain.
“This study raises the possibility that there may be too many synapses in the brains of patients with autism,” said senior author Azad Bonni, MD, PhD, the Edison Professor of Neuroscience and head of the Department of Neuroscience at Washington University School of Medicine in St. Louis. “You might think that having more synapses would make the brain work better, but that doesn’t seem to be the case. An increased number of synapses creates miscommunication among neurons in the developing brain that correlates with impairments in learning, although we don’t know how.”
Autism is a neurodevelopmental disorder affecting about one out of every 68 children. It is characterized by social and communication challenges.
How Does Autism Affect The Brain
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Autism is a brain disorder that affects how people interact with others. It occupies a spectrum, with severe autism at one end and high-functioning autism at the other. People with severe autism usually have intellectual impairments and little spoken language. Those with high-functioning autism have average or above average IQ, but struggle with more subtle aspects of communication, such as body language. As well as social difficulties, many individuals with autism show repetitive behaviors and have narrow interests.
The brains of people with autism process information differently to those of people without autism. The brain as a whole shows less coordinated activity in autism, for example. But whether individual brain regions themselves also work differently in autism is unclear. Watanabe et al. set out to answer this question by using a brain scanner to compare the resting brain activity of high-functioning people with autism to that of people without autism.
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Analysis Of Medication Use
Data on medication use was available for 832 individuals with ASD, of which 214 were categorized as medication users. For each AI that showed a significant effect of diagnosis in the primary analysis, a linear mixed model analysis was performed within-cases only, AI=medication+age+sex+random . Medication was coded as a binary variable .
Autistic People May Act In A Different Way To Other People
Autistic people may:
- find it hard to communicate and interact with other people
- find it hard to understand how other people think or feel
- find things like bright lights or loud noises overwhelming, stressful or uncomfortable
- get anxious or upset about unfamiliar situations and social events
- take longer to understand information
- do or think the same things over and over
If you think you or your child may be autistic, get advice about the signs of autism.
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The Brain Of Children With Autism Spectrum Disorder
24 August, 2020
If the brain of a child with autism spectrum disorder was a house, every room would be filled with noise, itd have complex wiring all over it, and its walls would be very sensitive to almost any stimulus. This excess of synapses or neural connections produces particular alterations in every child.
Scientific advances dont really matter. Its useless to continue learning about these neurological development disorders that affect a significant part of our population. The lack of awareness, stereotypes, and the misconceptions that we have about those who suffer from these disorders keep us from appreciating them as they are.
Undoubtedly, the problematic behavior of children and teenagers with ASD can put our patience to the test. They may have a privileged mind or serious intellectual deficits. However, despite their ever-so-enigmatic world, they surprise us with their strengths, sensibilities, needs, and affection.
Their families are commendable. They promote ceaseless and energetic love that not only has to deal with stereotypes, but also tries to create alliances with other social agents: doctors, specialists, teachers, psychologists, and everyone else whos devoted to these children.
Therefore, we can help them by trying to better understand their internal reality. Lets delve deeper into this.
by Angie Voyles Askham / 15 October 2020
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Measurement Of Cerebellar Vermis Area
In a separate process, the cross-sectional area of cerebellar vermis lobules VIVII was measured on the sagittal images . A straight line from the anterior limit of the primary fissure to the apex of the fourth ventricle formed the boundary between lobules IV and VIVII. The border between lobules VIVII and lobule VIII was defined by a straight line from the anterior limit of the prepyramidal fissure to the apex of the fourth ventricle. This cross-sectional area was used because: the area of lobules VIVII was found to be reduced in large studies of autism hypoplasia of the cerebellar vermis is highly correlated with hypoplasia of the cerebellar hemispheres in patients with autism a variable degree of Purkinje cell reduction or abnormality was demonstrated in the vermis in 13 of 19 post-mortem cases in autism patients, vermis hypoplasia is associated with deficits in shifting of attention, automatic orienting of attention and exploratory behaviour and this cross-sectional area can be measured quickly and accurately, making it a convenient index of cerebellar hypoplasia.
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Vaccines Dont Cause Autism
No link has been found between vaccines and autism, despite many scientific studies. Researchers have scrutinized the measles, mumps, and rubella vaccine since a 1998 British report raised concerns. That report has been retracted by the Lancet medical journal for poor science and fraud. Thimerosol, a form of mercury, was removed from childhood vaccines in 2001 as a precaution â though no good evidence ever linked it to autism.
White And Grey Matter Changes
Abnormal brain growth in autistic children primarily stems from cerebral white and grey matter. However, Herbert and colleagues asserted that this growth originates from the disproportionate increase of white matter, not grey matter . Abnormalities in white matter volume can be linked to differences in axonal density and organization, myelination abnormalities or the abnormal proliferation of glial cells . In two different studies with autistic children has been shown to significantly increase white matter rather than grey matter . However, it is not clear whether this increase in older children and adolescents is permanent or not . Even though the growth rate of grey matter has been shown to be smaller than that of white matter in early life, it is reported to be persistent in adulthood .
A reduction in fractional anisotropy alongside an increase in white matter volume may reflect abnormal connections in the form of increased non-myelinated white matter connectivity. Extremism in the weak links due to the activity of immature myelination may adversely affect information processing. A decrease in white matter integrity reduces the brain’s functional integration, a factor that has served as a basis of current theories about abnormal connections .
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Changes In Autism Severity Over Time
The white matter research builds on a previous MIND Institute study, which found that while many children experience fairly stable levels of autism symptoms throughout childhood, a significant portion can be expected to increase or decrease in their symptom severity over time.
This new analysis provides an important clue about the brain mechanism that may be involved in some of these changes, said Amaral.
Overly Persistent Brain Connections
First, the researchers conducted functional MRI scans on 90 male participants, of which 52 had a diagnosis of autism and 38 did not. The participants with autism were aged between 19 and 34, while the rest of the volunteers who acted as the control group had ages ranging between 20 and 34.
Then, to confirm the initial findings, the specialists compared their data with that collected from a further 1,402 people who participated in the Autism Brain Imaging Data Exchange study. Of these, 579 participants had autism. The remaining 823 participants did not have autism and acted as the control group.
Dr. Anderson and team used a novel fMRI method to explore brain activity in the participants on the current study. More specifically, they looked at the duration of connections established across brain regions.
We dont have good methods for looking at the brain on these timescales. Its been a blind spot because it falls in between typical MRI and studies, explains Dr. Anderson.
Thanks to the fMRI scans, the researchers were able to confirm that in the brains of people with autism, connections persist for more extended periods than they do in the brains of neurotypical individuals. In other words, in autism, the brain finds it harder to switch between processes.
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Different Types Of Autism
Changes in epigenetic marks in three brain regions from patients with ASD-revealed shared molecular and cellular pathways. Graphic: Courtesy of Drs. Daniel Geschwind and Shyam Prabhakar
UCLA scientists and their colleagues have found evidence that an abnormal pattern of brain cells is common in people with different types of autism-spectrum disorders. The abnormal pattern discovered in the study concerns a certain type of epigenetic mark, a chemical modification that occurs frequently on chromosomes and helps regulate the activity of nearby genes.
The findings suggest that although autism-spectrum disorders have multiple causes, they mostly involve problems in a common set of biological pathways, which are actions among certain molecules within a cell that lead to specific changes such as turning genes on or off or assembling new molecules. The findings may lead to a better understanding of how autism-spectrum disorders arise and perhaps one day to the development of drugs that target some of these irregular pathways.
The uniformity of this abnormal pattern in the autism samples was surprising, given that these samples were from people whose autism was known to have different causes, says Daniel Geschwind, MD , PhD, Gordon and Virginia MacDonald Distinguished Chair in Human Genetics. It suggests the possibility that different factors can cause autism-spectrum disorders through a set of common pathways.
Hyperconnectivity In The Brain Of Children With Autism Spectrum Disorder
In 2014, a group of researchers carried out a revealing study at Columbia University. The data of this study was published in Neuron magazine and it explained two very important things:
- The already-mentioned particularity of the brain of children with autism spectrum disorder: the excess of synapses or connections between neurons.
- An experimental treatment that could regulate hyperconnectivity .
Also, we must keep in mind that in addition to this synaptic singularity, there are other associated problems. For example, communication problems between different brain areas.
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