MRI detects brain differences in Down syndrome patients

Using ultrahigh-field magnetic resonance imaging (MRI) to map the brains of people with Down syndrome (DS), US researchers have detected subtle differences in the structure and function of the hippocampus — a region of the brain tied to memory and learning.

Such detailed mapping, made possible by the high-powered MRI, is significant because it allowed the research team to better understand how each subregion of the hippocampus in people with DS is functionally connected to other parts of the brain. Their study results have since been published in the journal Brain Communications.

“The ultimate goal of this approach is to have an objective technique to complement neuropsychological assessments to measure the functional skills of those with DS,” said senior author Professor Alberto Costa, from Case Western Reserve University.

Down syndrome is a genetic condition typically caused by having an extra copy of chromosome 21. The extra chromosome changes how a baby’s body and brain develop, which can cause mental and physical challenges throughout the person’s life.

Although abilities can range widely among people with DS, different types of cognitive skills are usually affected in a similar way in the same person. However, for a given person with DS, cognitive abilities that are heavily dependent on the hippocampus are especially affected.

“That’s why we focused on this structure deep inside the brain that is responsible for functions such as forming memories of episodes in one’s life and spatial memory,” Prof Costa said.

MRI scanners at ultrahigh magnetic field strengths are increasingly available for human research, allowing neuroscientists to map the brain at higher resolution without losing image clarity. Taking advantage of the increased resolution afforded by high-powered MRI, the researchers performed what is claimed to be the first in vivo comparison of volumes of different anatomical segments of the hippocampus between people with DS and ‘control’ individuals of the same age and sex without DS.

“The gains in sensitivity and image resolution achievable with ultrahigh-field MRI provide levels of detail and accuracy that have not previously been attainable in studies of live, non-sedated individuals with Down syndrome,” said first author Assistant Professor Katherine Koenig, also from Case Western Reserve University.

“We also found significant relationships between the size of subregions of the hippocampus and cognitive measures,” Prof Costa said. “Although more work will be necessary to validate some of our findings, these results support the investigation of specific MRI measures as potential markers to study drug efficacy for possibly enhancing cognitive function in persons with Down syndrome.”

Image caption: A 3D reconstruction of ultrahigh-field MRI images of the brain of an adult with Down syndrome, overlaid with a colour map of the subfields of the hippocampus.

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