# Cerebral pulsatility might be a driver of neurofunctional reorganization in the aging brain: an MRI and NIRS study

## TL;DR

This study suggests that increased cerebral pulsatility in older adults may lead to changes in brain function, possibly helping maintain cognitive abilities.

## Contribution

The study is the first to link cerebral pulsatility with hemispheric functional reorganization in aging using combined MRI and NIRS.

## Key findings

- Older adults showed a higher cerebral pulsatility index in the left hemisphere compared to the right.
- Greater pulsatility asymmetry in older adults correlated with task-evoked hemodynamic changes in the opposite hemisphere.
- Younger adults showed no such pulsatility asymmetry or correlations with task activation.

## Abstract

Age-related increases in cerebral pulsatility are thought to stress cerebral microcirculation, with effects that may vary across different brain regions. The aging brain also undergoes neurofunctional changes to preserve and, in some cases, enhance cognitive abilities. This study investigated the association between cerebral pulsatility and neurofunctional changes in aging. Sixty healthy adults were divided into two groups of younger (aged 19–31 years) and older adults (aged 62–75 years). Participants underwent near-infrared spectroscopy (NIRS) imaging, including a resting-state recording to capture the baseline cortical cerebral pulsatility index, followed by a Stroop task to assess cortical hemodynamic-evoked activity. Phase-contrast magnetic resonance imaging (PC-MRI) was also performed to measure pulsatility in the large arteries supplying the brain. Results indicated that older adults exhibited a significant interhemispheric difference in cerebral pulsatility index, with a higher index in the left hemisphere compared to the right. In older adults, a greater interhemispheric difference in cerebral pulsatility index was associated with larger task-evoked oxyhemoglobin concentration changes in the right hemisphere and smaller changes in the left hemisphere for the Stroop task. Younger adults, in contrast, showed no significant interhemispheric difference in the cerebral pulsatility index nor a significant correlation with task-evoked activations. These findings suggest that age-related changes in cerebral pulsatility might contribute to or potentially drive functional reorganization in the aging brain. Further investigation is needed to provide more insight into this finding.