What Do We Know About Autism and the Brain?
Over the past decade, foundational work searching for a single brain region responsible for ASD, and then for a single brain network, has provided a deeper understanding of how the brain works- but has raised as many questions as it has provided answers. We learned that the brain’s role in ASD is not as simple as pinpointing a single aspect of brain development or function. Early study findings showed that the brain works much like an orchestra, where individual sections of instruments have their own specific sheets of music- but they cannot create a symphony without incorporating all the instrument sections that make up the orchestra. “The current emphasis in ASD research,” says CAR child psychologist and assistant professor of Psychology in Psychiatry at the Children's Hospital of Philadelphia, Benjamin Yerys, PhD, “is to understand how the brain is connected. How is the structure of the connections within brain networks similar or different in autism? And how is the activity of brain regions that make up one network (or multiple networks) synchronized?” John Herrington, PhD, assistant professor in the Department of Child Psychiatry and Behavioral Science at the Perelman School of Medicine and associate director of CAR’s Developmental Neuroimaging Program, adds “To understand how the brain processes social information, you have to look at how brain networks involved in processing social information interact with the environment as well as with the other brain networks activated- but not directly involved- during social cognition.”
Imaging technology, whether magnetic resonance imaging (MRI) or magneto-encephalography (MEG), has unlocked many of the brain processing mysteries contributing to ASD. Previous research using MEG imaging, spearheaded by Timothy Roberts, PhD, vice-chair of research for the Department of Radiology and the Oberkircher Family Endowed Chair in Pediatric Radiology at CHOP, lead to the discovery of split second delays in sound processing in children with ASD, causing communication challenges. Building off this finding, Dr. Roberts and his team are using MEG imaging to determine if the delay in sound processing correlates with increased timing lags in both non- and minimally verbal children with ASD. “Including the entire spectrum of autism ability and disability in research is important so that tailored treatments are developed for all individuals with ASD,” says Dr. Roberts. His goal is to create unique behavioral plans for each child and collaborate with researchers around the world to share strategies.
Over the last decade, one of the richest sources of data on brain development in autism is the NIH-funded Infant Brain Imaging Study (IBIS), in which CAR has been a network site for the last decade. Juhi Pandey, PhD, is a pediatric neuropsychologist who leads the study at CAR. Initial findings from IBIS pinpointed differences in brain development in infant siblings of children with ASD who went on to be diagnosed with ASD by the age of two, when compared to the younger siblings who were not later diagnosed with ASD. The IBIS study is now moving into its third phase, following up with the initial study participants- now entering middle school- to examine the effects of the developmental differences seen in the initial brain scans. “It’s very exciting to reconnect with the families we met when IBIS began,” says Dr. Pandey. “We’re hoping this follow-up study will allow us to connect the dots between the brain differences we saw 10 years ago with the MRI scan and the behaviors we see today, giving us a more complete picture of the developmental trajectory of ASD”. Understanding this trajectory will help physicians and therapists make more informed treatment decisions, and will help families in planning for the future.
Dr. Pandey isn’t the only scientist at CAR hoping to expand the field’s understanding of brain development and function in ASD. Both Drs. Herrington and Yerys are currently examining the relationships between anxiety, ADHD, and ASD. “Co-occurring disorders like anxiety and ADHD are very common in autism and show some similarities in the brain. ADHD and anxiety, in particular, account for much of the variation in behaviors and functioning seen in individuals with ASD. If we fail to look at and tease apart the roles of each in a child’s brain function and behavior, we will leave gaps in our understanding of ASD”, Dr. Herrington says.
Perhaps one of CAR's greatest strengths is that each study is also designed with a bigger picture in mind. While each study at CAR can stand on its own as an individual and complete study, all of the Center's brain imaging studies are designed in a way that allows the imaging data from one study to be combined into a larger pool of data, with the goal of capturing the variations seen in ASD. “When we combine the imaging data with other genetic and behavioral data, and apply the appropriate statistical analysis, we’re able to see sub-groups of children with more homogeneous biological and behavioral patterns,” says Dr. Birkan Tunç, a computational scientist at CAR and a Research Assistant Professor in the Department of Psychiatry at University of Pennsylvania. Eventually, the scientists hope to be able to map intricate links between symptoms and underlying brain and genetic mechanisms, so that treatments can be designed to target these mechanisms.
Dr. Tunç and his colleagues at CAR are looking to not only provide insight on the wide spectrum of ASD symptoms, but also to standardize the measures and methods used in ASD research, which can benefit and advance the field as a whole. CAR researchers have painstakingly pooled together hundreds of structural MRI images from multiple studies in order to map how the brain is physically set up. This imaging data represents one of the largest brain imaging datasets from one MRI scanner existing in autism research. Using this dataset, PhD candidate Lisa Yankowitz, MA, and others found that the brains of children and young adults with ASD were larger than their typically developing peers. Additionally, their findings honed in on anatomical features that differ between these groups, suggesting that differences in the volume of particular regions are more prominent than differences in tissue density. Another research team at CAR, led by PhD candidate Caitlin Clements, MA, applied a new method of data analysis to synthesize the findings from more than a dozen previous fMRI studies, lending conclusive support for the social motivation hypothesis , which proposes that social difficulties in ASD are partially due to reduced activity in the brain’s reward system when responding to social rewards like smiling faces and non-social rewards like money.
Thanks to the strong foundation of CAR’s brain imaging research, we are now beginning to push the bounds of our understanding of the brain and ASD, setting up future possibility of personalized treatment options for individuals diagnosed with autism.