[Medscape] Decreased brain connections tied to autism


According to the researchers, signs of loss of communication between brain hemispheres have been linked to autism spectrum disorder (ASD) in adolescents and adults.

According to Clara Weber, a graduate student at Yale University, Newhaven, Connecticut, disruption in the white matter of the corpus callosum increases with age. This is a finding that could improve diagnosis and deepen understanding of the cause of the disease.

She also answered the sheet Medscape Medical News “We found that autism had progressive changes in both language and behaviour.” She gave a presentation on MRI analysis at the Radiological Society of North America (RSNA) 2021 annual meeting.

Previous studies have found differences in the microstructure of white matter between children with and without ASD. But the sample is so small that it is difficult to obtain significant statistical results.

To address this challenge, Weber and colleagues analyzed data on 583 patients from four groups based on a national autism database from previous studies. The 4 groups include:

  • 34 autistic infants and 121 children in treatment, of which 65.8% are male, the average age is 7 months old.
  • 57 autistic toddlers, 45 children in treatment, of which 73.5% are male, the mean age is 32 months old.
  • 106 autistic adolescents, 124 people in treatment, of which 50.8% are male, average age is 158 months.
  • 67 adults with autism, 29 people in treatment, of which 99% are male, average age is 230 months old.

They scanned the brain with strain-diffusion magnetic resonance imaging, an MRI technique that measures connectivity in the brain by looking at how fluid moves between regions of the white matter.

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And they used machines to look for correlations between anisotropy fractions, diffusivity, and radial diffusivity for radius, age, and sex. The anisotropy fraction measures the extent to which translational diffusion is confined to one side. If this value is 0, it means that the diffusion is not limited. A value of 1 means only one-way diffusion occurs, which is a good sign.

Mean diffusion refers to the mobility of molecules in the fluid, reflecting the density of cells. Radial radial diffusivity is the extent of diffusion shift perpendicular to the white matter band.

“When the cells become loose, the fluid diffuses in many directions, so the diffusivity is high,” says Weber.

The researchers found statistically significant reductions in the fraction of anisotropy in the anterior and mid-capsular range in adolescents and adults with autism, compared with controls. There is also a correlation between the autism diagnosis and the diffusivity and circularity values ​​in adults.

The researchers also showed that the change in the anisotropy fraction was related to age. Anisotropy fractions are lower in women, even after treatment after a definitive diagnosis.

They used a calculator to look at these correlations and found that the sample was about 75% correct (area under the curve, 0.75) in identifying patients with autism regardless of gender, age, and characteristics. structure.

“It would be a mistake for doctors to rely solely on MRI to diagnose a patient with autism,” Weber said. It is necessary to talk, evaluate, and know the patient’s abilities and behavior before a definitive diagnosis is made. So basically, we can use this to aid in diagnosis and even in treatment.”

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Dennis Dimond, who studied white matter in autistic people at the University of Calgary in Alberta, Canada but was not involved in this study, told the journal Medscape Medical News: “Discovering the difference between the corpus callosum between people with and without autism is not new. But I think testing on such a large sample reinforces the validity of that finding, which goes against the myths about flukes or anything else.”

According to him, the finding that differences in brain morphology are not present in infants but only in adults: “This further reinforces that this is a neurodevelopmental disorder that occurs occurs during brain development that contribute to personality in autism.”

Tests like these are needed, he said, because scientists still have a long way to go to understand the underlying mechanism behind the condition.

Translated by: Dieu Huong

Link to original post: https://www.medscape.com/viewarticle/964070?src=

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