New brain scan shows siblings-with-autism link


Siblings have a 1-in-5 chance of developing autism.

In a one-of-a-kind study, University of North Carolina researchers used a special kind of MRI called diffusion tensor imaging. It follows the movement of water through brain tissue. This allows scientists to look at 15 different brain connections in babies who had a sibling with autism. They found significant differences in 12 of the 15 connections in those who developed autism.

Kids without the disorder have stronger connections. Kids with autism are more likely to have a weaker connection.

"The children who went on to have autism, we can see differences as early as six months, and that over time, their brains changed less," said Dr. Jason Wolff, author of the study at University of North Carolina School of Medicine.

Currently it's almost impossible to diagnose autism at six months. These scans could offer a way to catch it much earlier.

"This is before we can really pick up any differences behaviorally," said Wolff. "If we could go earlier and earlier with our interventions, we could prevent autism from fully manifesting."

Wolff says the imaging could one day be used with behavioral exams to better diagnose autism. A recent study found when children as young as 18 months underwent therapy for autism, their IQ improved 14 points compared to other kids with autism.


BACKGROUND: Autism is a general term for a group of complex disorders of brain development. These disorders are characterized by difficulties in social interaction, verbal and nonverbal communication, and repetitive behaviors.

Autism can be associated with intellectual disability, difficulties in motor coordination, and attention and physical health issues such as sleep and gastrointestinal disturbances.

Some with certain types of autism excel in visual skills, music, math and art.

According to the U.S. Centers for Disease Control and Prevention, about 1 in 88 children in the United States has autism. This is a 10-fold increase in prevalence in 40 years.

Studies also show that autism is three- to four-times more common in boys. About 1 out of 54 boys and about 1 out of 252 girls are diagnosed with autism in the United States. This is more children than are affected by diabetes, AIDS, cancer, cerebral palsy, cystic fibrosis, muscular dystrophy or Downs syndrome combined. Government statistics suggest that prevalence rates have increased 10 to 17 percent annually in recent years.

DIAGNOSING AUTISM: Research now suggests that children as young as 1 year of age can show signs of autism. It's important to diagnose autism as soon as possible because early intervention may be a child's best hope. Some red flags that may suggest a child should be screened include:

  • No big smiles or joyful expressions by 6 months or thereafter
  • No back-and-forth sharing of sounds, smiles, or other facial expressions by 9 months or thereafter
  • No babbling by 12 months
  • No back-and-forth gestures such as pointing, showing, reaching or waving by 12 months
  • No words by 16 months
  • No two-word meaningful phrases by 24 months
  • Any loss of speech or babbling or social skills at any age

IMAGING STUDY: A new study, led by researchers from the University of North Carolina at Chapel Hill, found significant differences in brain development starting at 6 months of age in high-risk infants who later develop autism. The study suggests that autism does not appear suddenly in young children, but instead, develops over time during infancy.

Researchers studied 92 infants who had older siblings with autism and were therefore considered to be at high-risk themselves.

All participants had diffusion tensor imaging -- which is a type of MRI -- at 6 months and behavioral assessments at 24 months. Most also had additional brain imaging scans at either or both 12 and 24 months. At 24 months, 30 percent of the infants met the criteria for autism spectrum disorders while 70 percent did not.

The two groups differed in white matter fiber tract development -- pathways that connect brain regions -- as measured by fractional anisotropy. This measures white matter organization and development based on the movement of water molecules through brain tissue.

The researchers studied 15 separate fiber tracts. They found significant differences in FA trajectories in 12 out of the 15 tracts between infants who did develop autism versus those who did not. Infants who later developed autism had elevated fractional anisotropy at 6 months but then experienced slower change over time. By 24 months, infants with autism had lower FA values than those without autism.

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