The interaction effects of hypertension and aging on brain network in spontaneously hypertensive rats: A resting-state functional magnetic resonance imaging study

Although both hypertension and aging are considered primary risk factors for cognitive impairment, the combined effects of hypertension and aging on the functional network of the brain remain poorly understood. We aimed to investigate the interactions between hypertension and aging on the brain functional network in spontaneously hypertensive rats (SHRs). Using resting-state functional magnetic resonance imaging, we investigated the interactive effects of hypertension and aging on the brain network in terms of topological metrics and connectivity patterns. We detected changes in the functional connectivity density, topological metrics and functional network connectivity in 20-week-old and 80-week-old SHRs compared with those in age-matched Wistar-Kyoto rats. The functional hub in the brain shifted from the retrosplenial granule to the caudate putamen in SHRs from the young adult stage to the aged stage, while the small-world topology was preserved. We investigated the effects of interactions between hypertension and aging on functional connectivity involving a large-scale increased network in aged SHRs. We identified alterations in the functional hub and network associated with hypertension and aging. Our study supports the viewpoints of compensatory functional reorganization and neural plasticity. Network analysis is a promising technique for exploring brain function in rats and could provide potential neuroimaging biomarkers. It is essential to identify a neuroimaging biomarker that not only allows the prediction of brain abnormalities but also helps in understanding the neurobiological mechanisms underlying hypertension and aging.