Study Discovers Link Between Increased White Matter in the Brain and Poor Motor Skills in Children With Autism

Research Conducted at the Kennedy Krieger Institute Examines How Motor

Skill Deficits Can Provide Insight Into the Brain Basis of Autism

Jul 30, 2007, 01:00 ET from Kennedy Krieger Institute

    BALTIMORE, July 30 /PRNewswire-USNewswire/ -- A study published in the
 August issue of the journal Brain demonstrates, for the first time, an
 association between increased white matter volume and functional impairment
 in children with autism. Findings from researchers at the Kennedy Krieger
 Institute in Baltimore, Md., reveal that in children with autism, increased
 white matter volume in the motor region of the brain predicts poorer motor
 skills. Conversely, in typically developing children, increased white
 matter volume predicts improved motor skills, with a similar association
 observed in children with attention deficit/hyperactivity disorder (ADHD).
 The relationship between increased white matter volume and functional
 impairment, which appears to be specific to autism, may be representative
 of global patterns of brain abnormality in autism that not only contribute
 to motor dysfunction, but also to deficits in socialization and
 communication that define the disorder.
     Children with autism are typically motorically clumsy and awkward,
 similar to how they are socially clumsy and awkward. They often experience
 difficulties with basic motor control and with learning more complex motor
 skills, such as riding a tricycle, pumping their legs on a swing or
 buttoning, zipping and tying shoe laces. Additionally, high-functioning
 children with autism often excel in academic areas, such as math, as
 opposed to athletic activities, such as baseball. Because measures of motor
 function are highly quantifiable and reproducible, they are much easier to
 study than measures of social and communication behavior. Motor signs can
 serve as markers for deficits in parallel brain systems important for
 control of socialization and communication.
     Researchers utilized anatomic magnetic resonance imaging (aMRI)
 measures to study 76 children ages 8-12 years, including: 20
 high-functioning children with autism; a control group of 36 typically
 developing (TD) children; and a clinical control group of 20 children with
 ADHD, a developmental disorder which, like autism, has been found to be
 associated with impairments in motor execution and control. Findings show a
 robust association between increased white matter volume and basic motor
 skill impairment in children with autism, which suggests that it may be a
 defining biological feature of the disorder. Results demonstrate that the
 association of increasing white matter volume and poor motor function
 appears to be specific to autism, as this association was not observed in
 the TD or ADHD groups.
     "Carefully examining systems responsible for controlling simple aspects
 of behavior, such as basic motor control, can provide a window into
 understanding the systems that are responsible for control of more complex
 social and communicative behavior," said Dr. Stewart H. Mostofsky, lead
 study author and a pediatric neurologist in the Department of Developmental
 Cognitive Neurology at the Kennedy Krieger Institute. "This finding is an
 important step forward and will guide future research into the
 abnormalities associated with socialization and communication that define
 the disorder."
     Motor impairments, such as those seen in autism, offer valuable insight
 into the neurologic basis of developmental disorders. This is especially
 critical for autism and other disorders where the neurologic basis is not
 well understood. The most consistent neuroimaging finding in children with
 autism is increased brain volume, which has been primarily attributed to an
 increased volume of white matter (white matter consists of the connections
 between brain regions). To address the current lack of evidence showing
 that increases in white matter volume are associated with functional
 impairment in children with autism, researchers in this study examined
 associations between motor skills and white matter volume.
     Researchers assessed participants' basic motor skills using a
 standardized motor examination for children, the Physical and Neurologic
 Examination of Subtle Signs (PANESS), which has been used in past studies
 to demonstrate basic motor skill impairments in children with autism and
 ADHD. With the PANESS, higher scores indicate poorer performance.
 Consistent with previous findings, children with autism had significantly
 poorer motor performance (higher PANESS scores) than TD controls.
 Researchers identified a strong positive correlation between total PANESS
 score and white matter volume, revealing that increased white matter volume
 predicted poorer motor skills in these children.
     In contrast to the children with autism, TD children showed a
 significant correlation in the opposite direction, with increased white
 matter volume predicting better motor skills (lower PANESS scores). The
 correlation in children with ADHD was considerably different from the
 children with autism and similar to the TD group.
     In the future, Dr. Mostofsky and his colleagues hope to examine
 correlations of brain structure with motor performance using imaging
 techniques, such as diffusion tensor imaging (DTI), which can provide
 additional information about white matter connections. Upcoming studies may
 also extend this research to younger children and investigate, from a
 developmental perspective, what contributes to impaired acquisition and
 learning of motor skills in children with autism. Additionally, the brain
 systems involved in motor skill learning appear to be important for
 learning aspects of socialization and communication, including language.
 Future research that examines how these learning systems are affected in
 children with autism could therefore provide crucial information about the
 brain basis of the disorder and prove very valuable in guiding, and
 ultimately improving, therapy.
     About Autism
     Autism spectrum disorders (ASD) is the nation's fastest growing
 developmental disorder, with current incidence rates estimated at 1 in 150
 children. This year more children will be diagnosed with autism than AIDS,
 diabetes and cancer combined, yet profound gaps remain in our understanding
 of both the causes and cures of the disorder. Continued research and
 education about developmental disruptions in individuals with ASD is
 crucial, as early detection and intervention can lead to improved outcomes
 in individuals with ASD.
     About the Kennedy Krieger Institute
     Internationally recognized for improving the lives of children and
 adolescents with disorders and injuries of the brain and spinal cord, the
 Kennedy Krieger Institute in Baltimore, Md., serves more than 13,000
 individuals each year through inpatient and outpatient clinics, home and
 community services and school-based programs. Kennedy Krieger provides a
 wide range of services for children with developmental concerns mild to
 severe, and is home to a team of investigators who are contributing to the
 understanding of how disorders develop while pioneering new interventions
 and earlier diagnosis. For more information on Kennedy Krieger Institute,

SOURCE Kennedy Krieger Institute