Diastolic BP associated with biomarkers of cerebrovascular, Alzheimer’s disease
Diastolic blood pressure (BP) shows utility as a predictor of cerebrovascular disease and Alzheimer’s disease (AD) pathology, such that increased diastolic BP is associated with increased white matter hyperintensities (WMHs) and reduced hippocampal volume, according to a study.
The study included 227 members of the 1936 Birth Cohort. BP was measured biennially between 64 and 68 years, while brain magnetic resonance imaging (MRI) was performed at 68 years. Outcomes investigated included WMH abundance and hippocampal volume, whereas risk factors of interest were diastolic and systolic BP and their visit-to-visit variability.
In regression models, higher diastolic BP predicted increased WMH (p=0.044) and smaller hippocampi (p=0.006), with diastolic BP variability linked to lower hippocampal volume (p=0.033). On the other hand, higher systolic BP predicted larger hippocampi (p=0.013).
The observed relationships were independent of confounding life-course risk factors. Moreover, BP-lowering medication, which did not modify the relationships, was independently associated with increased WMH (p=0.011).
Researchers noted that the present data offer insight into the complex and differing relationships between BP components and brain pathology, and may explain the heterogeneous relationships between BP and cognition reported in previous studies.
“Treating systolic hypertension may have the consequence of accelerating hippocampal atrophy, whereas treating diastolic hypertension and reducing its long-term variability could ameliorate hippocampal atrophy and cerebrovascular disease, both risk factors for dementia,” they said, adding that targeting diastolic hypertension should be a primary goal for reducing neurodegeneration in older age.
Common in older age, hypertension has been shown to be associated with MRI markers of brain degeneration that accompany ageing and dementia. Cerebrovascular disease is visible on MRI scans as hyperintense regions known as WMHs, which are in turn associated with reduced cognitive performance and dementia. On the other hand, reduced hippocampal volume is a marker of hippocampal atrophy and is a useful indicator of AD pathology. [BMJ Open 2013;3:e003423; J Neurol Neurosurg Psychiatry 2007;78:1325–301; Neurobiol Aging 2010;31:378–86]