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Researchers Probe Environmental Risk Factors for Autism

By Chelsea E. Toledo, M.A. on April 19, 2017

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Background: Environmental risk factors comprise exposures and other biological features unrelated to DNA that are associated with an increased likelihood of developing a certain condition. In the case of Autism Spectrum Disorder (ASD), chemical exposures, birth complications, parental age and other factors encountered before or after birth have been identified as environmental risk factors.

 

What’s New: On March 17, 2017, the journal Molecular Autism published an evidence-based review of more than 100 potential environmental risk factors for ASD, ranking the strength of their association with ASD. The researchers looked at the evidence from 32 previously published meta-analyses and systemic reviews, each of those analyzing up to 25 studies on a single risk factor. From that extensive pool of data, they were able to conclude that:

 

  • Advanced parental age and birth complications that cause trauma or oxygen deprivation are strongly related to a person’s risk of developing ASD. In addition, vitamin D deficiency appears to be common in children with ASD.
  • Cesarean births, as well as obesity and diabetes during pregnancy, have a slight association with ASD in the resulting offspring.
  • Vaccination, smoking during pregnancy, thimerosal exposure, and assisted reproductive technology most likely do not influence a person’s risk of developing ASD.
  • Some heavy metals, such as mercury and lead, may have an association with ASD, and merit further investigation.

 

Why it’s important: This study helps to define which environmental factors for ASD merit a closer look from the research community. Future studies could further investigate those relationships to determine whether they do indeed influence the likelihood of ASD.


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New Brain-Imaging Study Identifies Autism in Infants

By Chelsea E. Toledo, M.A. on March 7, 2017
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Background: Early diagnosis of Autism Spectrum Disorder (ASD) is a topic of great interest to parents and researchers alike. Studies have repeatedly shown that the earlier a child received intervention for ASD, the more benefits that child will gain related to the behavioral, communicative, and social symptoms of the disorder. However, in the United States – where one in 68 children receives an ASD diagnosis – the average age of diagnosis is 4 years old. Furthermore, standard practices aren’t yet in place for clinicians to diagnose ASD before 2 years old, when a great deal of the development of language and social skills has already taken place.

 

What’s new: On February 16, 2017, the journal Nature published a study outlining a potential measure for predicting ASD diagnosis before symptoms are apparent in young children. The researchers performed brain imaging at three different points in time on a total of 148 infants – 42 of whom defined as low-risk and 106 of whom were defined as high-risk, based on whether or not the infants had older siblings with ASD. Measuring the growth of the brain’s surface area at 6, 12, and 24 months, the researchers noted a trend in accelerated growth (especially in the brain’s cortex, which processes information from the environment) in the infants who were ultimately diagnosed with ASD. The researchers used this information to develop an algorithm that accurately predicted 80 percent of ASD cases in a separate group of infants.

 

Why it’s important: This is the first study to follow the same children from infancy to toddlerhood, tracing risk factors for diagnosis to actual clinical outcomes. Future studies could combine the researchers’ algorithm with other useful predictors (such as genetics and behavior) to improve its accuracy, with the aim of developing an early diagnostic technique.


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Exercise’s Therapeutic Affects Vary in People with ASD

By Chelsea E. Toledo, M.A. on February 15, 2017
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Background: While no “one-size-fits-all” treatment exists for people with autism spectrum disorder (ASD), a variety of therapies are available to ease the social, behavioral and communicative symptoms for those who might need help. Research has shown that exercise can improve cognitive function in people with learning difficulties, but exercise has not been widely studied as a potential therapy for ASD.

 

What’s New: On July 13, 2016, the Journal of Autism and Developmental Disorders published a meta-analysis – or an umbrella study combining the results from previous research on a single topic – on the cognitive effects of exercise in individuals with ASD. The researchers reviewed data from 22 studies, with a total of 579 participants between the ages of 3 and 29. They found that exercise had a modest effect on cognitive function overall, but that the effect wasn’t consistent for all cognitive symptoms. For instance, the study suggested that exercise could improve individuals’ performance on tasks such as assigning value to coins, but was less effective at improving executive function tasks such as repeating a series of digits that appeared previously on a screen.

 

Why it’s important: This study supports exercise as an inexpensive intervention for people with ASD to aid in some cognitive functions alongside other therapies. Future studies could pinpoint what types of exercise are most helpful for people on various parts of the spectrum.


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New Genetics Study Finds Autism-Innate Immunity Link

By Shana R. Spindler, Ph.D. on January 18, 2017
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Background: Have you ever used one object in two ways? For example, you can use a spatula to flip an egg or swat a fly. The cells in our bodies do this all the time with the genes in our DNA. If something goes wrong with a gene, several problems in the body can occur. Think about the spatula. If the spatula factory accidentally shapes the flat surface like a spoon, you’ll have a hard time flipping eggs or smashing a fly. These are different activities, but the misshapen spatula affects both.

 

To learn more about the genetics behind autism spectrum disorder (ASD), researchers are looking at co-occurring symptoms that happen more frequently with autism than in the general population, such as seizures, infections, gastro-intestinal disorders, heart problems, and psychiatric disorders. The researchers hypothesize that these activities in the body may share a common gene or set of genes that, when disrupted, increase risk for ASD core symptoms and co-occurring symptoms at once.

 

What’s new: Researchers from Harvard Medical School and the Massachusetts Institute of Technology made an important link between ASD and the immune system by combining genetic data collected during other studies. Using a series of statistics calculations, the researchers found that genes involved in innate immunity were most likely to have problems across co-occurring conditions with ASD.

 

Innate immunity is your first line of defense to foreign invaders, like harmful bacteria. The researchers narrowed in on two parts of innate immunity that appear to be most significant. One is a group of proteins, called toll-like receptors, which help the body recognize microbes. The second includes chemokines, small signaling molecules that help attract nearby immune system cells.

 

Why it’s important: These results suggest a path forward to look at the genetic and environmental interactions behind some cases of autism. A common mechanism causing distinct symptoms may also aid in the development of targeted ASD therapies.


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Maternal Vitamin D Deficiency Linked to ASD-Traits in Kids

By Chelsea E. Toledo, M.A. on December 26, 2016
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Background: Vitamin D is an important nutrient that not only aids the development and maintenance of the bones but also brain function. While most people in the developed world get sufficient vitamin D from regular sun exposure, deficiencies can arise in areas with long, cold winters or when people avoid the sun altogether. Studies have demonstrated that vitamin D deficiencies during pregnancy are associated with an increased risk of cognitive impairment and motor development in the resulting offspring.

 

What’s New: On November 29, 2016, Molecular Psychiatry published a study examining the relationship between vitamin D deficiencies in expecting mothers and the presence of behavior traits associated with Autism Spectrum Disorder, or ASD, among their children. The researchers assessed vitamin D levels in preserved blood samples taken from 4,229 mothers mid-way through their pregnancies, as well as from cord blood samples taken at birth. They then screened the resulting children (who, at the time of the study, averaged six years of age) for ASD traits using the Social Responsiveness Scale, or SRS. They found that children whose mothers were deficient in vitamin D both mid-way through pregnancy and at birth had higher average SRS scores – indicating the presence of ASD traits – than those whose mothers either had no deficiency or were only deficient at one point in time.

 

Why it’s important: This is the first study to identify a possible link between the level of vitamin D in a mother’s blood mid-way through her pregnancy and autism-related behaviors in the resulting child. Future studies could evaluate whether routine, inexpensive vitamin D supplementation during pregnancy could reduce the incidence of ASD in children.


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Infection During Pregnancy Increases Baby’s Autism Risk

By Chelsea E. Toledo, M.A. on December 13, 2016
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Background: While no singular cause has been identified for Autism Spectrum Disorder (ASD), research points to several risk factors. These include patterns in genetics as well as in external environmental conditions. One question under debate by researchers is whether infections during pregnancy could increase the risk of ASD in the resulting offspring. Multiple studies have investigated this theory, with conflicting results. To better understand a larger trend in smaller studies, researchers will sometimes conduct a meta-analysis – combining the results of the studies to create a bigger picture of the study effect in action. This statistical approach is especially useful when individual reports disagree in their conclusions.

 

What’s New: On June 6, 2016, Brain, Behavior, and Immunity published a meta-analysis of 15 studies examining the link between maternal infections and ASD risk. In total, the researchers evaluated data from more than 40,000 ASD cases studied between 2004 and 2015. Within the larger group, individual studies focused on viral, bacterial and fungal infections impacting women during all three trimesters of pregnancy. In combining all these data, the researchers observed a 12 percent increase in the risk of an ASD diagnosis in the offspring of mothers who experienced an infection during pregnancy. The effect was most pronounced among expectant mothers who were in their second trimester of pregnancy, whose infections led to hospitalization, and among those with bacterial infections of the skin or urinary tract. Viral infections during pregnancy and infections during the first trimester, however, were not associated with increased ASD risk.

 

Why it’s important: Following conflicting evidence in previous studies, this study suggests that babies born to mothers who experienced certain types of infections during pregnancy may in fact have a higher risk of being diagnosed with ASD. Of note, risk severity depended on the time of infection exposure (first, second or third semester) and the site of infection. With large enough sample sizes, future studies could more definitively prove or disprove that link – focusing especially on bacterial infections leading to hospitalization.


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Therapy Using Parent Training Linked to Improved ASD Symptoms

By Chelsea E. Toledo, M.A. on November 28, 2016
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Background: The typical symptoms of autism spectrum disorder (ASD) – which include differences in behavior, communication, and social interaction – usually appear in early childhood. Multiple longitudinal studies have suggested that children who are exposed to early interventions for ASD experience improved outcomes as they develop.

 

What’s New: On October 25, 2016, The Lancet published a study evaluating the long-term effectiveness of a therapy based on communication training for parents of young children with ASD. This work is a follow up of an earlier study of the Preschool Autism Communication Trial (PACT). Between 2008 and 2009, the researchers administered PACT training to parents of 77 children between the ages of 2 and 4 who had ASD. The recent follow-up study showed that the children whose parents had undergone 12 sessions of the training experienced a greater reduction in scores related to symptom severity than the 75 children whose parents did not undergo the training. The training allowed parents to watch videotaped interactions of themselves with their children alongside a therapist, who provided tailored support.

 

Why it’s important: This is the first follow-up to a randomized and controlled study that shows an early intervention, in this case PACT, can decrease ASD symptom severity over the long term. Future evaluations could determine whether a parent-centered training like PACT should be considered a standard intervention for children with ASD – and especially for those with severe symptoms.


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