Summary: A new neuroimaging study reveals preschool aged children with ASD have significant differences in the basal ganglia network and paralimbic-limbic network in the brain compared to their peers who were not diagnosed with autism.
Preschoolers with autism spectrum disorder, or ASD, have abnormal connections between certain networks of their brains that can be seen using a special MRI technique, according to a study published online in the journal Radiology. Researchers said the findings may one day help guide treatments for ASD.
ASD refers to a group of developmental disorders characterized by communication difficulties, repetitive behaviors and limited interests or activities. Young children with ASD can usually be diagnosed within the first few years of life. Early diagnosis and intervention are important because younger patients typically benefit most from treatments and services to improve their symptoms and ability to function.
While developments in brain imaging have enabled the discovery of abnormal brain connectivity in younger children with ASD, the phenomenon has not yet been fully investigated at the brain network level. Brain networks are areas of the brain connected by white matter tracts that interact to perform different functions.
For the new study, researchers looked for differences in brain connectivity in children with ASD using an MRI technique called diffusion tensor imaging (DTI). The technique provides important information on the state of the brain’s white matter.
Researchers compared DTI results between 21 preschool boys and girls with ASD (mean age of 4-and-a-half years old) with those of 21 similarly aged children with typical development. They applied graph theory to the DTI results to understand more about the level of connectivity between brain networks. By applying graph analysis to the DTI results, researchers can measure the relationships among highly connected and complex data like the network of connections that forms the human brain.
Compared with the typically developed group, children with ASD demonstrated significant differences in components of the basal ganglia network, a brain system that plays a crucial role in behavior. Differences were also found in the paralimbic-limbic network, another important system in regulating behavior.
“Altered brain connectivity may be a key pathophysiological feature of ASD,” said study co-author Lin Ma, M.D., from the Department of Radiology at Chinese PLA General Hospital in Beijing. “This altered connectivity is visualized in our findings, thus providing a further step in understanding ASD.”
The results suggest that these altered patterns may underlie the abnormal brain development in preschool children with ASD and contribute to the brain and nervous system mechanisms involved in the disorder. In addition, the identification of altered structural connectivity in these networks may point toward potential imaging biomarkers for preschool children with ASD.
“The imaging finding of those ‘targets’ may be a clue for future diagnosis and even for therapeutic intervention in preschool children with ASD,” Dr. Ma said.
For instance, Dr. Ma said, in the future this type of brain imaging might aid in the delivery of ASD therapies for children like repetitive transcranial magnetic stimulation, or TMS, and transcranial direct current stimulation, or tDCS. TMS involves using a magnet to target and stimulate certain areas of the brain, while tDCS relies on electrical currents to deliver therapy. Both are being investigated as possible treatments for ASD.
Funding: The study was funded by Beijing Nova Program, National Natural Science Foundation of China, Translational Medicine Project of PLA General Hospital 2016, Natural Science Foundation of Beijing Municipality.
Source: Linda Brooks – RNSA
Publisher: Organized by NeuroscienceNews.com.
Image Source: NeuroscienceNews.com image is credited to the researchers.
Original Research: Open access research for “Alterations of White Matter Connectivity in Preschool Children with Autism Spectrum Disorder” by Shi-Jun Li, Yi Wang, Long Qian, Gang Liu, Shuang-Feng Liu, Li-Ping Zou, Ji-Shui Zhang, Nan Hu, Xiao-Qiao Chen, Sheng-Yuan Yu, Sheng-Li Guo, Ke Li, Mian-Wang He, Hai-Tao Wu, Jiang-Xia Qiu, Lei Zhang, Yu-Lin Wang, Xin Lou, and Lin Ma in Radiology. Published online March 27 2018.
Alterations of White Matter Connectivity in Preschool Children with Autism Spectrum Disorder
Although the underlying pathophysiology and neurologic basis of autism spectrum disorder (ASD) in patients remain unclear, especially in children with ASD, altered brain connectivity is a key feature of ASD pathophysiology. Recent neuroimaging findings indicate that ASD is associated with atypical brain connectivity, but the specific neuropathologic aberrations in ASD are yet to be determined. Multiple studies of functional connectivity identified patterns of both functional hypo- and hyperconnectivity in adults and children with ASD. Diffusion-tensor imaging (DTI) studies of white matter integrity revealed similar atypical connectivity patterns in children and adolescents with ASD. A recent theory that attempts to reconcile the conflicting results in the literature suggests that hyperconnectivity of brain networks may be more characteristic in young children with ASD, whereas hypoconnectivity is more prevalent in adolescents and adults with the disorder compared with individuals with typical development (TD). However, this atypical brain connectivity in ASD has only been observed at regional levels. Brain connectivity at the network level has not yet been fully investigated, particularly in preschool children with ASD.
The topologic properties of brain networks have been characterized by using graph theory analysis. This is typically achieved through magnetic resonance (MR) imaging and neurophysiologic data, and from both functional and structural perspectives. With this framework, DTI has been used to assess white matter connectivity in the brains of individuals with ASD. This approach has also been used to identify how the topologic organization of the brain network is affected by other psychiatric disorders, such as Alzheimer disease, multiple sclerosis, and epilepsy.
On the basis of these recent findings, we hypothesized that abnormalities in preschool children with ASD are mainly associated with white matter hyperconnectivity, specifically in networks involving the basal ganglia and the paralimbic-limbic system because alterations in these networks are closely related to repetitive and stereotyped behaviors, as well as learning and memory impairment. In our study, we attempted to characterize the whole-brain connectivity in children with ASD and in children with TD by using DTI.