Brainstem connections to the cortex weaken with aging
High-resolution brain scans comparing older to younger adults showed that long-range connections between 58 brainstem nuclei and the cortex weakened with age.
Limit: Compares different groups at a single time point rather than tracking changes over time
Edited by Boris Djordjevic · AgingResearch.News
Researchers in an observational study reported in a preprint mapped brain connections in young adults, older adults, and people with isolated REM sleep behavior disorder, an early stage of a protein-linked brain disease. The abstract does not report participant counts or ages. Using high-resolution 7-Tesla functional magnetic resonance imaging (fMRI), a scan measuring blood flow, the authors mapped connectivity between 58 brainstem nuclei—clusters of nerve cells—and the cortex, the brain's outer layer.
Long-range brainstem-to-cortex connectivity weakened with aging and further in the sleep disorder. However, the two conditions affected distinct systems. Aging involved arousal- and cognition-related nuclei and association cortex, regions that integrate information. The sleep disorder involved sleep- and autonomic-related nuclei and extended to sensory-motor cortex, which processes sensations and movement. These changes were associated with distinct metabolic profiles, neurotransmitter chemical messengers, and gene activity signatures. Independent 3-Tesla brain scans reproduced the broader patterns.
Why it matters
Mapping brainstem pathways in older adults helps clarify how healthy aging differs from the earliest stages of neurodegenerative disease. The findings may help researchers distinguish normal age-related changes in cognition from early disease processes.
Caveats
The observational, cross-sectional design compares different groups at a single time point rather than tracking changes in the same individuals over time. In addition, the abstract does not report participant numbers or characteristics, and the findings are reported in a preprint that has not yet been peer-reviewed.
The paper
Charting vulnerability of brainstem functional pathways in aging and prodromal synucleinopathy
Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical S
bioRxiv, Oct 28, 2026, Open access, CC BY-NC, Preprint, not peer-reviewed
