Central artery stiffness, baroreflex sensitivity, and brain white matter neuronal fiber integrity in older adults

Abstract

Cerebral hypoperfusion elevates the risk of brain white matter (WM) lesions and cognitive impairment. Central artery stiffness impairs baroreflex, which controls systemic arterial perfusion, and may deteriorate neuronal fiber integrity of brain WM. The purpose of this study was to examine the associations among brain WM neuronal fiber integrity, baroreflex sensitivity (BRS), and central artery stiffness in older adults. Fifty-four adults (65±6 years) with normal cognitive function or mild cognitive impairment (MCI) were tested. The neuronal fiber integrity of brain WM was assessed from diffusion metrics acquired by diffusion tensor imaging. BRS was measured in response to acute changes in blood pressure induced by bolus injections of vasoactive drugs. Central artery stiffness was measured by carotid-femoral pulse wave velocity (cfPWV). The WM diffusion metrics including fractional anisotropy (FA) and radial (RD) and axial (AD) diffusivities, BRS, and cfPWV were not different between the control and MCI groups. Thus, the data from both groups were combined for subsequent analyses. Across WM, fiber tracts with decreased FA and increased RD were associated with lower BRS and higher cfPWV, with many of the areas presenting spatial overlap. In particular, the BRS assessed during hypotension was strongly correlated with FA and RD when compared with hypertension. Executive function performance was associated with FA and RD in the areas that correlated with cfPWV and BRS. These findings suggest that baroreflex-mediated control of systemic arterial perfusion, especially during hypotension, may play a crucial role in maintaining neuronal fiber integrity of brain WM in older adults.

Effects of Arterial Stiffness on Brain Integrity in Young Adults From the Framingham Heart Study

“…This hypothesis is supported by the present work using DTI in a young adult sample, wherein we found continuous associations between CFPWV and microstructural WM injury in several tracts (particularly the corpus callosum) that have been reported to be affected in elderly people with Alzheimer disease 29 . Our finding also extends observations from a recent tract-based spatial statistic DTI study 3 that identified similar associations in a sample of 55 older individuals. Despite the fact that voxel-based and tract-based studies are two methods using a fairly different approach, the prior study and the current data both identified the corpus callosum, corona radiata and internal capsule as regions that are particularly vulnerable to increased aortic stiffness.…”

“…1, 26 In particular, the association between central artery stiffness and WMH burden has been frequently and consistently reported among older individuals 3, 4, 27 . In the FHS Offspring cohort of older individuals, recent findings suggest that only CFPWV and MAP are associated with WMH burden.…”

“…Recent analyses from the Framingham Heart Study (FHS) and other cohorts suggest that, in older individuals, vascular remodeling may also play a central role in the development of structural brain injury 3, 4 , which have been associated with reduced cognitive ability 5-7 and increased likelihood of incident dementia. 8 …”

Cerebral blood flow in normal aging adults: cardiovascular determinants, clinical implications, and aerobic fitness

“…Consistently, our recent study also demonstrated that aortic stiffening and blunted cardiovagal baroreflex sensitivity are associated with reductions in brain neuronal fiber integrity and executive function performance in older adults (Tarumi et al . ). Nevertheless, the potential causal effect of arterial stiffening or blunted baroreflex sensitivity on cognitive impairment requires further research, and it should also be kept in mind that brain neurodegenerative disease per se may impair the baroreflex function.…”

Cerebral Microbleeds and Thrombolysis

“…11 The consistent loss of smooth muscle cells and presence of arteriolar injury have the functional consequences of impaired autoregulation, with incapacity to accommodate alterations of systemic blood pressure. 14,15 …”