Hypertensive Adults Exhibit Lower Myelin Content: A Multicomponent Relaxometry and Diffusion Magnetic Resonance Imaging Study

Abstract

BACKGROUND: It is unknown whether hypertension plays any role in cerebral myelination. To fill this knowledge gap, we studied 90 cognitively unimpaired adults, age range 40 to 94 years, who are participants in the Baltimore Longitudinal Study of Aging and the Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing to look for potential associations between hypertension and cerebral myelin content across 14 white matter brain regions. METHODS: Myelin content was probed using our advanced multicomponent magnetic resonance relaxometry method of myelin water fraction, a direct and specific magnetic resonance imaging measure of myelin content, and longitudinal and transverse relaxation rates ( R 1 and R 2 ), 2 highly sensitive magnetic resonance imaging metrics of myelin content. We also applied diffusion tensor imaging magnetic resonance imaging to measure fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity values, which are metrics of cerebral microstructural tissue integrity, to provide context with previous magnetic resonance imaging findings. RESULTS: After adjustment of age, sex, systolic blood pressure, smoking status, diabetes status, and cholesterol level, our results indicated that participants with hypertension exhibited lower myelin water fraction, fractional anisotropy, R 1 and R 2 values and higher mean diffusivity, radial diffusivity, and axial diffusivity values, indicating lower myelin content and higher impairment to the brain microstructure. These associations were significant across several white matter regions, particularly in the corpus callosum, fronto-occipital fasciculus, temporal lobes, internal capsules, and corona radiata. CONCLUSIONS: These original findings suggest a direct association between myelin content and hypertension and form the basis for further investigations including longitudinal assessments of this relationship.

Optimal systolic and diastolic blood pressure threshold that associated with lower risk of white matter hyperintensity progression

“…The relationship between WMH and large artery sclerosis could not exclude multitype target organ damage caused by similar vascular risk as earlier studies failed to determine the association between intracranial large-artery stenosis and WMH (Park et al, 2015). Patients with hypertension tend to develop lower myelin content, have more severe brain microstructure impairment (Laporte et al, 2023a), have a higher risk of perivascular inflammation (Solé-Guardia et al, 2023), have lower cerebrovascular density, and have lower branch numbers (Zhang et al, 2021), which are potential mechanisms of WMH (Ungvari et al, 2021). Data from the Baltimore Longitudinal Study of Aging (BLSA) and the Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing (GESTALT) studies analyzed the association between hypertension and myelin content measured by Diffusion tensor imaging (DTI) and showed that patients with hypertension presented lower myelin content and higher impairment to the brain microstructure, especially in the corpus callosum, fronto-occipital fasciculus, temporal lobes, internal capsules, and corona radiata (Laporte et al, 2023a).…”

“…Patients with hypertension tend to develop lower myelin content, have more severe brain microstructure impairment ( Laporte et al, 2023a ), have a higher risk of perivascular inflammation ( Solé-Guardia et al, 2023 ), have lower cerebrovascular density, and have lower branch numbers ( Zhang et al, 2021 ), which are potential mechanisms of WMH ( Ungvari et al, 2021 ). Data from the Baltimore Longitudinal Study of Aging (BLSA) and the Genetic and Epigenetic Signatures of Translational Aging Laboratory Testing (GESTALT) studies analyzed the association between hypertension and myelin content measured by Diffusion tensor imaging (DTI) and showed that patients with hypertension presented lower myelin content and higher impairment to the brain microstructure, especially in the corpus callosum, fronto-occipital fasciculus, temporal lobes, internal capsules, and corona radiata ( Laporte et al, 2023a ). Additionally, elevated arterial stiffness was associated with lower microstructural integrity of white matter, and this association was also stronger and significant in the splenium of the corpus callosum and internal capsules, which have been reported to be sensitive to elevated arterial stiffness ( Laporte et al, 2023b ).…”

Current Perspectives: Obesity and Neurodegeneration - Links and Risks

“… 158 , 159 Recent studies have used magnetic resonance imaging to quantify myelin water fraction to provide a surrogate measure of myelin content. Obesity 160 and common comorbidities such as hypertension 161 and metabolic syndrome 162 have been associated with lower myelin content in the brain. Together, these findings suggest that obesity-related ROS production can disrupt endothelial cell function and decrease white matter integrity.…”

Fornix fractional anisotropy mediates the association between Mediterranean diet adherence and memory four years later in older adults without dementia

“…The brain’s white matter is vulnerable to risk factors modulated by diet, such as hypertension (e.g., Laporte et al, 2023) and obesity (Wassenaar et al, 2019). Diet could impact the brain through several brain correlates, including white matter, which are known to contribute to cognition (Rodrigues et al, 2020).…”