Research reveals brain differences at 6 months in infants who develop autism

February 23, 2012

An ongoing study that could lead to an imaging biomarker for autism as early as 6 months, before the onset of observable behavioral symptoms, may also eventually provide practitioners an avenue for earlier intervention in autism spectrum disorders

Autism does not appear suddenly in young children but develops over time in the first year of life, suggests a study that found significant differences starting at 6 months in white matter fiber tract development-pathways that connect brain regions-between high-risk infants who later developed autism spectrum disorders (ASDs) and those who did not.

The investigators said finding a possible imaging biomarker for ASDs during a child’s first half-year, before the onset of symptoms, is an important step toward diagnosing autism earlier than currently possible just through behavioral observations and could lead to earlier intervention. They noted that to date these are the earliest brain differences related to later autism symptoms.

Researchers tracked 92 high-risk infant siblings from an ongoing imaging study of autism, applying diffusion tensor imaging at 6 months and behavioral assessments at 24 months. The imaging showed that fractional anisotropy trajectories for 12 of 15 white matter fiber tracts reported to be associated with ASDs or related behaviors differed significantly in the 28 infants who developed autism.

The researchers also cited recent British findings that high-risk infants later diagnosed with autism showed different brain responses, both from low-risk babies and from high-risk babies who did not develop the condition, saying the 2 findings strengthen one another. This study analyzed dynamic eye gaze shifts of 104 babies aged 6 to 10 months and then again at 3 years and found that those who went on to develop autism had unusual patterns of brain activity in response to eye contact with another person.

An earlier study that analyzed resting state electroencephalographic data collected from 79 infants had 80% accuracy in distinguishing 9-month-old, high-risk infants from controls by detecting abnormal activity in the front left side of the brain, which is involved in language and social development. The researchers noted that at 9 months, babies undergo important changes in their brain functions that are critical for the emergence of higher-level social and communication skills, which often are impaired in ASDs.

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