Has a certain smell ever triggered a memory from your childhood? The hippocampus plays a part in that connection as it plays a critical role in the formation, organization, and storage of new memories as well as connecting certain sensations and emotions to these memories. Previous studies have found that memory impairment in Down syndrome (DS) is linked to inhibition in the hippocampus. Now a new study by researchers from Case Western Reserve University, Cleveland Clinic, University Hospitals, and collaborators detected subtle differences in the structure and function of the hippocampus.
Using ultra-high field magnetic resonance imaging (MRI) the researchers were able to map the brains of people with DS. Their findings are published in the journal Brain Communications in a paper titled, “High resolution structural and functional MRI of the hippocampus in young adults with Down syndrome.”
“Down syndrome is the phenotypic consequence of trisomy 21, with clinical presentation including both neurodevelopmental and neurodegenerative components,” wrote the researchers. “Although the intellectual disability typically displayed by individuals with Down syndrome is generally global, it also involves disproportionate deficits in hippocampally-mediated cognitive processes. Hippocampal dysfunction may also relate to Alzheimer’s disease-type pathology, which can appear as early as the first decade of life and becomes universal by age 40. Using 7-tesla MRI of the brain, we present an assessment of the structure and function of the hippocampus in 34 individuals with Down syndrome (mean age 24.5 years ± 6.5) and 27 age- and sex-matched typically developing healthy controls.”
“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,” explained Alberto Costa, MD, PhD, professor of pediatrics and psychiatry at the Case Western Reserve University School of Medicine and the study’s senior author.
In the group with DS, bilateral hippocampi showed widespread reductions in the strength of functional connectivity, predominately to frontal regions (p < 0.02). Age was not related to hippocampal volumes or functional connectivity measures in either group, but both groups showed similar relationships of age to whole-brain volume measures (p < 0.05).
“The gains in sensitivity and image resolution achievable with ultra-high field MRI provide levels of detail and accuracy that have not previously been attainable in studies of live, non-sedated individuals with Down syndrome,” added Katherine Koenig, an assistant professor of radiology at the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University and the study’s first author.
More work will be needed to validate some of the findings, but this work provides a first demonstration of the usefulness of high-field MRI to detect subtle differences in structure and function of the hippocampus in individuals with Down syndrome.