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by Angie Voyles Askham / Brain connectivity patterns in people with autism and other neuropsychiatric conditions are more closely related to genetics than to phenotypic traits, according to two new studies. The findings highlight why a single brain biomarker for autism has remained elusive, the researchers say. The condition’s genetic heterogeneity has hampered the search for a shared brain signature: More than 100 genes have been identified as strongly linked to autism, and multiple copy number variations (CNVs) — deleted or duplicated stretches of genetic code — can increase a person’s likelihood of the condition. Autism also often overlaps with other conditions, such as schizophrenia and attention-deficit/hyperactivity disorder (ADHD), making autism-specific markers difficult to disentangle. Common variants tied to autism overlap strongly with those linked to schizophrenia and high IQ, for example, whereas rare autism-linked variants track with low IQ. According to the new papers, however, autism’s genetic heterogeneity corresponds to similarly disparate maps of ‘functional connectivity’ — a measure of which brain areas activate in sync while the brain is at rest. “What we’re seeing is that these groups of variants have specific functional connectivity signatures,” says lead investigator Sébastien Jacquemont, associate professor of pediatrics at the University of Montreal in Canada. The findings need to be replicated, says Aaron Alexander-Bloch, assistant professor of psychiatry at the University of Pennsylvania and the Children’s Hospital of Philadelphia, who was not involved in the work, but they point to the importance of subgrouping study participants based on their underlying genetics. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28490 - Posted: 09.28.2022

by Charles Q. Choi Infection during pregnancy may be associated with having an autistic child simply because mothers of autistic children are prone to infections, a new study finds. The results suggest that “common infections during pregnancy do not seem increase their children’s risk of autism,” says study investigator Martin Brynge, a psychiatrist and doctoral student of global public health at the Karolinska Institutet in Stockholm, Sweden. “Prevention of maternal infections would likely not affect the prevalence of autism in the population.” A great deal of previous research has linked maternal infection during pregnancy with autism and intellectual disability in children. Whether the former causes the latter, however, has remained uncertain. For instance, both autism and intellectual disability are linked with gene variants that may influence the immune system, so mothers of children with either condition may also just be more vulnerable to serious infections. The new study analyzed data from 549,967 children, including 267,995 girls, living in Stockholm County who were born between 1987 and 2010; about 34,000 of the children had been exposed to a maternal infection requiring specialized health care, according to data from Sweden’s National Patient Register and National Medical Birth Register. Of the exposed children, 3.3 percent have autism, compared with 2.5 percent of unexposed children — a 16 percent increase in the chance of autism. But maternal infection in the year before pregnancy was also linked with a 25 percent greater chance of autism. “Mothers who had an infection during pregnancy may not be comparable to those mothers without infections,” Brynge says. “There may be systematic differences at the group level.” © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 11: Emotions, Aggression, and Stress
Link ID: 28488 - Posted: 09.24.2022

by Nora Bradford A well-studied brain response to sound, called the M100, appears earlier in life in autistic children than in their non-autistic peers, according to a new longitudinal study. The finding suggests that the auditory cortex in children with autism matures unusually quickly, a growth pattern seen previously in other brain regions. “It’s a demonstration that when we look for autism markers in the brain, they can be very age-specific,” says lead investigator J. Christopher Edgar, associate professor of radiology at the Children’s Hospital of Philadelphia in Pennsylvania. For that reason, longitudinal studies such as this one — in which Edgar and his colleagues assessed children at up to three different ages — are essential, he adds. “If the two populations being studied have different rates of brain maturation, then the pattern of findings changes across time.” At the time of the first magnetoencephalography (MEG) scan, when the children were 6 to 9 years old, those with autism were more likely to have an M100 response to a barely audible tone in the right hemisphere than non-autistic children were. But this difference disappeared in the next two visits, presumably because the M100 response typically appears during early adolescence. By contrast, the M50 response, which occurs throughout life, beginning in utero, showed no significant difference between the two groups at any visit. The team also evaluated ‘phase locking,’ a measure of how similar a participant’s neural activity is from scan to scan within a certain frequency band. Autistic participants demonstrated more mature phase-locking patterns at the first visit, which then diminished at the later two visits. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 28478 - Posted: 09.17.2022

by Charles Q. Choi Children with autism show atypical development of brain regions connected to the amygdala, an almond-size brain structure involved in processing fear and other emotions, a new study finds. The brain regions most affected vary between autistic boys and girls, the study also shows, adding to the growing body of evidence for sex differences in autism, researchers say. “Better understanding of amygdala development and its connectivity can aid in the development of novel biomarkers to study brain and social health,” says Emma Duerden, assistant professor of applied psychology at Western University in London, Canada, who was not involved in the study. The amygdala is a central hub for brain circuits involved in social function. Previous studies have found it to be enlarged in some autistic children compared with non-autistic children, a difference that may be linked with anxiety and depression. In the new study, researchers used structural magnetic resonance imaging to track the growth of 32 brain regions with direct connections to the amygdala. The study participants included 282 autistic children, 93 of whom are female, and 128 non-autistic children, 61 of whom are female. The researchers scanned each child up to four times — when the children were 39, 52, 64 and 137 months old, on average. They also measured the children’s autism traits and social difficulties using a questionnaire filled out by parents, called the Social Responsiveness Scale-2. Autistic children had larger amygdala-connected brain regions than non-autistic children at all ages. The differences grew over time and were most apparent among the autistic children with prominent social difficulties. The researchers found no differences in the size of brain areas not directly connected to the amygdala between children with and without autism. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 11: Emotions, Aggression, and Stress
Link ID: 28398 - Posted: 07.14.2022

by Charles Q. Choi The primordial cells that give rise to most other brain cells do not proliferate in a typical way in autistic people — and that could explain how common traits emerge from a range of genetic origins, according to a new study. The idea that autism disrupts the proliferation of neural precursor cells isn’t new, but until now, few studies had investigated how that difference arises. In the new study, scientists fashioned neural precursor cells out of cord blood cells from five autistic boys ages 4 to 14 and, to serve as controls, either their non-autistic brothers or unrelated non-autistic people. Three of the autistic children have idiopathic cases, in which there is no known genetic cause for their autism; the other two have deletions in 16p11.2, a chromosomal region linked to autism and other neuropsychiatric conditions. Three of the autistic children have macrocephaly, or a large head. Neural precursors from the autistic boys all proliferated in atypical ways, the scientists found. Among children with macrocephaly, this growth was accelerated, leading to 28 to 55 percent more cells than in the non-autistic controls after six days. In contrast, cells from the other two boys, both with idiopathic autism, grew more slowly and more of those cells died, yielding 40 to 65 percent fewer cells than in controls after six days. “Despite the fact that these individuals are genetically distinct, especially the idiopathic individuals, it is amazing they have a common developmental process dysfunction — control of proliferation,” says study co-lead investigator Emanuel DiCicco-Bloom, professor of neuroscience, cell biology and pediatrics at Rutgers University in Piscataway, New Jersey. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28363 - Posted: 06.11.2022

by Laura Dattaro Two new studies untangle how various classes of genetic variants underpin the vast differences in traits seen among people diagnosed with autism. The studies were published yesterday in Nature Genetics. “The fundamental question behind this is heterogeneity in autism,” says Varun Warrier, a postdoctoral researcher in Simon Baron-Cohen’s lab at the University of Cambridge in the United Kingdom and an investigator on one of the studies. The presence and intensity of core autism traits and co-occurring conditions vary widely among autistic people. The new studies, from largely independent teams, sought to unravel how different categories of genetic variants — rare, common, inherited and spontaneous — contribute to this heterogeneity. Though the two sets of findings conflict in some ways — potentially because of methodological differences — the papers add to the evidence that common and rare variants contribute to autism’s genetic architecture differently, says Yufeng Shen, associate professor of systems biology at Columbia University, who was not involved in either study. “When we say different, it’s not black and white,” Shen says. “They overlap, but it seems like, qualitatively, they have different contributions.” Warrier and his colleagues analyzed genetic and behavioral data from 12,893 autistic people. The data came from the Autism Genetic Resource Exchange, the Longitudinal European Autism Project, the Simons Simplex Collection and SPARK. (The Simons Simplex Collection and SPARK are funded by the Simons Foundation, Spectrum’s parent organization.) © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28356 - Posted: 06.07.2022

by Rachel Zamzow Inflammation may inflate or thin out brain regions tied to autism and schizophrenia, researchers report in a new study. The findings add nuance to the long-held hypothesis that immune activation elevates the risk for neurodevelopmental conditions. Autism, for example, is associated with prenatal exposure to infection, previous studies show. Taking a different approach, the new work focuses on how a genetic predisposition to inflammation affects brain development in the general population, says John Williams, research fellow at the University of Birmingham in the United Kingdom, who conducted the work with lead researcher Rachel Upthegrove, professor of psychiatry and youth mental health at the university. By pinpointing where inflammation leaves its mark in the brain, the findings serve as a guidepost for future studies of people with neuropsychiatric conditions, he says. “We think that it points to something that’s fairly transdiagnostic.” For their analyses, the team drew on brain imaging and genetic data from 10,828 women and 9,860 men in the general population who participated in the UK Biobank. They explored how 1,436 possible structural changes in the brain track with having single-nucleotide variants previously shown to increase circulating levels of five inflammatory molecules — interleukin 1 (IL-1), IL-2, IL-6, C-reactive protein and brain-derived neurotrophic factor. Three variants thought to boost IL-6 were associated with 33 structural changes, most notably increased volume in the middle temporal gyrus and fusiform gyrus, and decreased cortical thickness in the superior frontal gyrus — all brain areas implicated in autism. Variants associated with other inflammatory molecules did not track with brain changes, the researchers found. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28317 - Posted: 05.07.2022

Rachel Zamzow Andrew Whitehouse never expected his work as an autism researcher to put him in danger. But that’s exactly what happened soon after he and his colleagues reported in 2020 that few autism interventions used in the clinic are backed by solid evidence. Within weeks, a range of clinicians, therapy providers and professional organizations had threatened to sue Whitehouse or had issued complaints about him to his employer. Some harassed his family, too, putting their safety at risk, he says. For Whitehouse, professor of autism research at the Telethon Kids Institute and the University of Western Australia in Perth, the experience came as a shock. “It’s so absurd that just a true and faithful reading of science leads to this,” he says. “It’s an untold story.” In fact, Whitehouse’s findings were not outliers. Another 2020 study—the Autism Intervention Meta-Analysis, or Project AIM for short—plus a string of reviews over the past decade also highlight the lack of evidence for most forms of autism therapy. Yet clinical guidelines and funding organizations have continued to emphasize the efficacy of practices such as applied behavior analysis (ABA). And early intervention remains a near-universal recommendation for autistic children at diagnosis. The field urgently needs to reassess those claims and guidelines, says Kristen Bottema-Beutel, associate professor of special education at Boston College in Massachusetts, who worked on Project AIM. “We need to understand that our threshold of evidence for declaring something evidence-based is rock-bottom low,” she says. “It is very unlikely that those practices actually produce the changes that we’re telling people they do.” © 1986–2022 The Scientist.

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28291 - Posted: 04.20.2022

by Peter Hess Two separate sets of neurons govern the social difficulties and repetitive behaviors associated with mutations in TSHZ3, a top autism candidate gene, according to a new mouse study. The results could help advance a circuit-level understanding of autism, says co-lead investigator Laurent Fasano, senior researcher at the French National Center for Scientific Research and Aix-Marseille University in Marseille, France. “Although we know that the results obtained with animal models will not necessarily be transposable to humans, we hope that our results will stimulate additional studies that will benefit autistic people.” In the new work, Fasano and his colleagues homed in on cortical projection neurons, which connect the cerebral cortex to other brain regions, and striatal cholinergic interneurons, which produce the chemical messenger acetylcholine in the striatum. Together, these cell types form part of the corticostriatal circuit, the dysfunction of which has been implicated in autism. “Whereas many studies have linked defective development and function of the corticostriatal pathway to autism, there is little evidence for an implication of striatal cholinergic interneurons,” says co-lead investigator Lydia Kerkerian-Le Goff, senior researcher at the French National Center for Scientific Research and Aix-Marseille University. Picking out specific cell types in the corticostriatal circuit and linking them to distinct autism-related behaviors is important, says Michael Ragozzino, professor of behavioral neuroscience at the University of Illinois Chicago, who was not involved in the study. The study’s results suggest that repetitive behaviors and social deficits, autism’s core traits, have different neurobiological roots, he says. “This may also suggest that different therapeutics may need to be developed to effectively treat both symptom domains.” © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28284 - Posted: 04.16.2022

by Laura Dattaro Some genomic areas that help determine cerebellar size are associated with autism, schizophrenia and bipolar disorder, according to a new study. But heritable genetic variants across the genome that also influence cerebellar size are not. The cerebellum sits at the base of the skull, below and behind the much larger cerebrum. It coordinates movement and may also play roles in social cognition and autism, according to previous research. The new work analyzed genetic information and structural brain scans from more than 33,000 people in the UK Biobank, a biomedical and genetic database of adults aged 40 to 69 living in the United Kingdom. A total of 33 genetic sequence variants, known as single nucleotide polymorphisms (SNPs), were associated with differences in cerebellar volume. Only one SNP overlapped with those linked to autism, but the association should be explored further in other cohorts, says lead investigator Richard Anney, senior lecturer in bioinformatics at Cardiff University in Wales. “There’s lots of caveats to say why it might be worth following up on,” Anney says. “But from this data alone, it’s not telling us there’s a major link between [autism] and cerebellar volume.” So far, cognitive neuroscientists have largely ignored the cerebellum, says Jesse Gomez, assistant professor of neuroscience at Princeton University, who was not involved in the work. The new study represents a first step in better understanding genetic influences on the brain region and its role in neurodevelopmental conditions, he says. “It’s a fun paper,” Gomez says. “It’s the beginning of what’s an exciting revolution in the field.” Of the 33 inherited variants Anney’s team found, 5 had not previously been significantly associated with cerebellar volume. They estimated that the 33 variants account for about 50 percent of the differences in cerebellar volume seen across participants. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 5: The Sensorimotor System
Link ID: 28215 - Posted: 02.23.2022

by Holly Barker New software uses machine-learning to automatically detect and quantify gait and posture from videos of mice moving around their cage. The tool could accelerate research on how autism-linked mutations or drug treatments affect motor skills, says lead researcher Vivek Kumar, associate professor of mammalian genetics at The Jackson Laboratory in Bar Harbor, Maine. Most efforts to analyze motor behavior involve placing a mouse on a treadmill or training it to walk through a maze. These assays are a simple way of testing speed, but they restrict the animals’ movement and force mice to walk in an unnatural way. The algorithm processes footage from an overhead camera and tracks 12 key points on a mouse’s body as it freely explores its surroundings. As the animal wanders, the software detects the position of its limbs and other body parts, automatically generating data on its gait and posture. The researchers described their method in January in Cell Reports. Kumar’s group trained the software by feeding it about 8,000 video frames that had been manually annotated to tag key points on the animal’s body, such as the nose, ears and tip of the tail. They repeated the process with a variety of different strains to teach the algorithm to recognize mice of all shapes and sizes. The trained software learned to read the rodent’s pose, which was further analyzed to extract more detailed information, such as the speed and length of each stride and the width of the mouse’s stance. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 5: The Sensorimotor System
Link ID: 28186 - Posted: 02.05.2022

by Lauren Schenkman Autism is thought to arise during prenatal development, when the brain is spinning its web of excitatory and inhibitory neurons, the main signal-generating cell types in the cerebral cortex. Though this wiring process remains mysterious, one thing seemed certain after two decades of studies in mice: Although both neuron types arise from radial glia, excitatory neurons crop up in the developing cortex, whereas inhibitory neurons, also known as interneurons, originate outside of the cortex and then later migrate into it. Not so in the human brain, according to a study published in December in Nature. A team of researchers led by Tomasz Nowakowski, assistant professor of anatomy at the University of California, San Francisco, used a new viral barcoding method to trace the descendants of radial glial cells from the developing human cortex and found that these progenitor cells can give rise to both excitatory neurons and interneurons. “This is really a paradigm-shifting finding,” Nowakowski says. “It sets up a new framework for studying, understanding and interpreting experimental models of autism mutations.” Nowakowski spoke with Spectrum about the discovery’s implications for studying the origins of autism in the developing brain. Spectrum: Why did you investigate this topic? Tomasz Nowakowski: My lab and I are interested in understanding the early neurodevelopmental events that give rise to the incredible complexity of the human cerebral cortex. We know especially little about the early stages of human development, primarily because a lot of our knowledge comes from mouse models. As we’ve begun to realize over the past decade, the processes that underlie development of the brain in humans and mice can be quite different. © 2022 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28165 - Posted: 01.22.2022

by Anna Goshua A variety of traits, including developmental delay and intellectual disability, characterize people with mutations in the autism-linked gene MYT1L, according to a new study. The gene encodes a transcription factor important for cells that make myelin, which insulates nerve cells and is deficient in some forms of autism. The work, published 8 November in Human Genetics, represents the most detailed study of the traits associated with MYT1L mutations to date. “We wanted to gather more cases to bring a clearer clinical and molecular picture of the condition for lab scientists, clinicians and also for patients and families,” says study investigator Juliette Coursimault, a physician-researcher in the genetics department at Rouen University Hospital in France. She and her co-researchers described 62 people, whereas previous literature included only 12 cases. The new characterization will “benefit clinicians’ diagnosis and treatment strategies when a patient with MYT1L mutation arrives in their clinic,” says Brady Maher, a lead investigator at the Lieber Institute for Brain Development at Johns Hopkins University in Baltimore, Maryland, who was not part of the study. The researchers identified and reviewed data for 22 people with MYT1L mutations who had been described in the academic literature, and collected clinical and molecular data from an additional 40 people, aged 1 to 34 years old, with likely or confirmed pathogenic variants of MYT1L. They recruited the participants through Rouen University Hospital and data-sharing networks such as GeneMatcher, which connects clinicians and researchers. © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28122 - Posted: 12.22.2021

by Anna Goshua Researchers have identified hundreds of genes that may contribute to autism, but these genes can’t fully account for the condition’s traits. Studies from the past decade implicate an additional layer of ‘epigenetic’ complexity: chemical tags called methyl groups laid on top of a person’s genetic code. Enzymes that are mutated in some people with autism or related conditions attach the chemical tags to DNA. And that pattern of methyl marks across the genome can influence which genes are active or inactive at any given time. Much remains to be understood about this process, called DNA methylation. Here we describe how and when methylation happens and what researchers know about its relationship to autism. What is methylation? Methylation is the process by which enzymes called methyltransferases deposit methyl chemical groups onto DNA. The presence of these tags usually turns off nearby genes. The complete set of such modifications to the genome over a person’s lifetime is known as the methylome. Most methyl tags are deposited onto the DNA nucleotide called cytosine (C) whenever it occurs next to the nucleotide guanine (G). This CpG methylation begins during gestation and can change across the lifespan. Tags are also sometimes added to cytosines followed by other nucleotides, however. High levels of non-CpG methylation in the brain may be critical for neuron development. 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28115 - Posted: 12.15.2021

by Anna Goshua Mice that lack one copy of TBX1, a gene in the autism-linked 22q11.2 chromosomal region, produce too little myelin — the fatty insulation that surrounds neurons — and perform poorly on tasks that measure cognitive speed, according to a new study. The work, published 5 November in Molecular Psychiatry, may offer insight into the mechanisms that underlie impaired cognitive function in some people with a 22q11.2 deletion, and possibly other copy number variants (CNVs). “The myelin changes could potentially emerge as a common neuronal deficit that mediates cognitive changes among many CNV cases,” says lead investigator Noboru Hiroi, professor of pharmacology at the University of Texas Health Science Center at San Antonio. Neuronal axons — the projections that conduct nerve impulses — are coated with myelin, which serves to speed up electrical transmission. The brains of autistic people and several mouse models of autism have disruptions in myelin, previous research has shown. These connecting fibers are the “highways of the brain,” says Valerie Bolivar, research scientist at the New York State Department of Health’s Wadsworth Center in Albany. “If the highway doesn’t work, you can’t get your goods from one place to another as fast.” TBX1 encodes a protein that regulates the expression of other genes during brain development. Deleting one copy of TBX1 leads to social and communication deficits in mice, according to previous studies by Hiroi’s team. © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28103 - Posted: 12.08.2021

by Charles Q. Choi One injection of a potential new gene therapy for Angelman syndrome forestalls many of the neurodevelopmental condition’s key traits, according to early tests in mice. “While additional pharmacology and safety studies are needed, our viral vector can potentially provide transformative therapeutic relief with a single dose,” says lead investigator Benjamin Philpot, professor of neuroscience at the University of North Carolina at Chapel Hill. Angelman syndrome, which affects about one in 20,000 children, is associated with significant developmental delays and, often, autism. It arises from mutations or deletions in the maternal copy of the UBE3A gene, which encodes a protein that helps regulate the levels of other important proteins. There are no treatments specifically for Angelman syndrome, but several gene therapies are under development. One in clinical trials requires repeat injections in the spine and has shown serious side effects at high doses. These therapies all aim to restore UBE3A function in neurons. One challenge, though, is that neurons produce several variants, or ‘isoforms,’ of the UBE3A protein that vary slightly in length; in mice, for example, neurons make two isoforms in a ratio of about four short forms for every long one. In contrast to other gene therapies, the new one generates short and long forms of the UBE3A protein at nearly the same ratio as is seen in mouse neurons. Such proportions “may be important for therapeutic efficacy,” says Eric Levine, professor of neuroscience at the University of Connecticut in Farmington, who was not involved in this study. © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 13: Memory and Learning
Link ID: 28093 - Posted: 12.01.2021

by Niko McCarty Growing numbers of autistic children are diagnosed with the condition before age 3, in the United States, and those diagnoses tend to precede the start of any interventions or developmental services, according to a new study based on parent surveys. Children traversing autism’s ‘diagnostic odyssey’ a decade ago were typically diagnosed years later, and only after they had begun receiving services. The analysis included data from 2,303 autistic children aged 2 to 17 years from the National Survey of Children’s Health, which asks parents questions about the children in their household. The selected participants, split into three groups based on their age, either had a plan for early intervention or had received special services to meet developmental needs. The oldest children, aged 12 to 17 at the time of the survey, had been diagnosed at about age 5 and a half years, on average. Their first intervention or developmental service occurred at around age 5. By contrast, the youngest cohort, aged 2 to 5, had been diagnosed at about age 2 and a half years and started their first intervention or developmental services at roughly the same age. The results are based on parent responses to a question — “How old was your child when a doctor or other health care provider first said they had autism?” — so the findings likely skew toward younger ages than if the researchers had used clinical diagnoses. Also, the study omitted children who did not already have a diagnosis, which might have pushed the average age older. Still, the findings suggest that the time between getting a diagnosis and accessing services is shrinking. © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28084 - Posted: 11.20.2021

by Angie Voyles Askham Two new unpublished studies presented virtually at the 2021 Society for Neuroscience annual meeting offer insights into synapse development: One maps the trajectories of synapse formation across nine species, and the other characterizes the earliest synapses to arise in the human brain. The findings could help researchers better understand how developmental changes may alter synaptic function and contribute to autism. “In order to understand whether something is deviated from neurotypical, you actually have to know what neurotypical is,” says Sam Wang, professor of neuroscience at Princeton University and principal investigator on one of the new studies. Across species, early brain development is defined by a period of exuberant synapse formation, followed by one in which any unnecessary connections are pruned. Disruption to either process may explain some of the atypical development seen in autism, but much about synaptic development remains unknown. For example, when Wang and his colleagues began sifting through the literature to figure out when in development cortical synapses are most abundant and whether that timing shows shared patterns across species, they couldn’t find any studies that had charted the full developmental trajectory from birth to adulthood, says Henk-Jan Boele, a postdoctoral researcher in Wang’s lab who presented the work. So they decided to plot that course themselves, for as many species of mammals as they could find data for. © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28074 - Posted: 11.13.2021

by Angie Voyles Askham The gut microbiome is having a moment. An explosion of research over the past decade has delved into a possible connection between the microbiome and brain conditions, including autism. Once-fringe microbial treatments for autism, such as fecal transplants and probiotic pills, are receiving serious scientific attention and funding. It’s still an open question, however, whether the microbiome has a direct effect on autism traits. The most promising data supporting this idea involve altering a mouse’s gut flora, but it is not clear exactly what the mechanism is or if this work translates to people. And the evidence from human studies linking microbes to autism is thin, if a 2021 review of the literature is any guide. Adding to the uncertainty, new unpublished data from one of the largest human studies yet suggests that the link between an atypical gut microbiome and autism is driven solely by a difference in diet. At least four small firms are spearheading early-stage trials of ‘bug as drug’ treatments for autism-associated traits. But until those trials play out, the role of the microbiome in autism is far from clear, says Gaspar Taroncher-Oldenburg, a consultant on microbiome research for the Simons Foundation, Spectrum’s parent organization. “There’s no denying that the microbiome is part of the [autism] conversation,” Taroncher-Oldenburg says. “But it’s a very complex conversation, and we’re only starting to scratch the surface.” A potential connection between the gut microbiome and autism first surfaced in the 1990s, after parents reported changes in their autistic children’s behavior when the children took antibiotics, which kill some gut bacteria. A 2000 study following up on this idea showed that 8 of 10 autistic children taking an antibiotic had temporary improvements in their speech and sociability. Later work associated an atypical gut microbiome with unusual social behaviors in mice. © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 28043 - Posted: 10.20.2021

by Angie Voyles Askham An intranasal form of the hormone oxytocin is no more effective than placebo at increasing social behaviors in autistic children, according to what may be the largest clinical trial of the treatment to date. The results were published today in The New England Journal of Medicine. Because of oxytocin’s role in strengthening social bonds, researchers have considered it as a candidate treatment for autism for more than a decade. Small trials hinted that the hormone could improve social skills in some autistic people, such as those with low blood levels of oxytocin or infants with Prader-Willi syndrome, an autism-related condition. But the new results, based on 250 autistic children, suggest that “oxytocin, at least in its current form, is probably not helpful for the majority of kids with autism,” says Evdokia Anagnostou, professor of pediatrics at University of Toronto in Canada, who was not involved in the new work. The null results “change things,” says lead researcher Linmarie Sikich, associate professor of psychiatry and behavioral sciences at the Duke Center for Autism and Brain Development in Durham, North Carolina. “Most people still felt like there was a good chance that this would be treatment for many people with autism.” This type of research is prone to publication bias, in which non-significant results are less likely to be published than significant ones, says Daniel Quintana, senior researcher in biological psychiatry at the University of Oslo in Norway, who was not involved in the study. For that reason, the new work is “an important contribution to the field,” he says, but “it does not alone put to rest the idea of using intranasal oxytocin as an autism treatment.” © 2021 Simons Foundation

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 8: Hormones and Sex
Link ID: 28036 - Posted: 10.16.2021