Aging and Hypertension – Independent or Intertwined White Matter Impairing Factors? Insights From the Quantitative Diffusion Tensor Imaging

Abstract

Aging disrupts white matter integrity, and so does continuous elevated blood pressure that accompanies hypertension (HTN). Yet, our understanding of the interrelationship between these factors is still limited. The study aimed at evaluating patterns of changes in diffusion parameters (as assessed by quantitative diffusion fiber tracking – qDTI) following both aging, and hypertension, as well as the nature of their linkage. 146 participants took part in the study: the control group ( N = 61) and the patients with hypertension ( N = 85), and were divided into three age subgroups (25–47, 48–56, 57–71 years). qDTI was used to calculate the values of fractional anisotropy, mean, radial and axial diffusivity in 20 main tracts of the brain. The effects of factors (aging and hypertension) on diffusion parameters of tracts were tested with a two-way ANOVA. In the right hemisphere there was no clear effect of the HTN, nor an interaction between the factors, though some age-related effects were observed. Contrary, in the left hemisphere both aging and hypertension contributed to the white matter decline, following a functional pattern. In the projection pathways and the fornix, HTN and aging played part independent of each other, whereas in association fibers and the corpus callosum if the hypertension effect was significant, an interaction was observed. HTN patients manifested faster decline of diffusion parameters but also reached a plateau earlier, with highest between-group differences noted in the middle-aged subgroup. Healthy and hypertensive participants have different brain aging patterns. The HTN is associated with acceleration of white matter integrity decline, observed mainly in association fibers of the left hemisphere.

Neurofilament‐light in former athletes: a potential biomarker of neurodegeneration and progression

“…Also, it should be noted that through our study we cannot determine causation. Although, repetitive concussions may explain our findings, comorbidities such as hypertension [31], obesity [32], or sleep apnea [33] should be considered as potential confounding factors as they may be responsible for imaging differences which are seen between individuals. In addition, we followed up the ExPro subgroup for only 2 years which is a relatively short period to track neurodegeneration.…”

Associations between modifiable risk factors and white matter of the aging brain: insights from diffusion tensor imaging studies

“…Higher arterial stiffness has been identified as a cause of higher blood pressure, which increases with aging, and has shown a negative association with WM integrity (Maillard et al., 2016). A recent study reported a significant hypertension by age interaction, suggesting accelerated WM loss (reflected by higher MD, AxD, RD) in middle-aged hypertensive adults, but only in the left hemisphere (Sabisz et al., 2019). Findings from a small number of longitudinal studies that have examined the relationship between WM integrity and hypertension over a period of 2 to 10 years have, however, been inconsistent.…”

“…Hypertension, or high blood pressure, in middle-aged and older adults is related to DTI metrics that reflect compromised WM integrity, particularly lower FA and higher MD values (Allen et al., 2016, Bender and Raz, 2015, de Groot et al., 2015, Gons et al., 2012, Hannawi et al., 2018, Maillard et al., 2012, Mcevoy et al., 2015, Power et al., 2017, Salat et al., 2012, Suzuki et al., 2017) (but see the study by Bender et al., 2016, de Groot et al., 2016, Sabisz et al., 2019). Interestingly, the associations between blood pressure and FA and MD are already detectable in preclinical stages (Maillard et al., 2012, Salat et al., 2012) (but see the study by Suzuki et al., 2017), and remain significant after controlling for age and WM lesions (Power et al., 2017, Salat et al., 2012).…”

Age‐related changes in cerebrovascular health and their effects on neural function and cognition: A comprehensive review

“…Because of its strong connection to arterial stiffness and cerebral vascular disease, it is difficult to separate hypertension effects from the effects of other vascular impairments. Hypertension has been linked to declining brain health, including decreased gray matter volume, decreased cortical thickness, decreased fractional anisotropy, and increased white matter lesions (Gonzalez et al., 2015; Jennings & Zanstra, 2009; Sabisz et al., 2019). It has also been linked to declining cognition across a number of domains, including memory, executive function, and processing speed (Iadecola et al., 2016).…”