The association of blood pressure with reduced cognitive function and Alzheimer’s disease dementia has been widely studied, yet few studies have explored the biological mechanisms linking blood pressure and cognitive impairment. Pulse pressure increases linearly with age and can be one of the indications of vascular aging. Pulse pressure has been found to increase the risk of developing Alzheimer’s disease dementia, but whether this association arises exclusively from its secondary subclinical cerebrovascular disease or is directly related to the pathophysiology of Alzheimer’s disease is unclear. To this end, Daniel A. Nation, PhD, from the University of California, San Diego Health System on Aging, and colleagues conducted a study, the results of which were published online in the November 13, 2013 issue of Neurology. The authors found that pulse pressure was associated with biomarkers of Alzheimer’s disease in older adults with normal cognitive function.
The study included 177 cognitively normal elderly subjects (aged 55-100 years) without a history of stroke, who underwent blood pressure testing to determine patient PP (systolic-diastolic blood pressure) and lumbar puncture to detect levels of Aβ1-42 and P-tau in the cerebrospinal fluid. The relationship between PP and biomarkers of Alzheimer’s disease was further evaluated using Pearson’s correlation coefficient with multiple linear regression, controlling for age, sex, APOE genotype and body mass index.
The results showed that elevated PP was significantly associated with increased P-tau, decreased Aβ1-42 and increased P-tau/Aβ1-42 ratio. After controlling for relevant variables, PP remained significantly associated with P-tau and P-tau/Aβ1-42 ratio, but no longer with Aβ1-42. Posthoc multifactorial analysis suggested that increased PP was associated with all biomarkers in relatively younger subjects (age 55-70 years), while it was not associated in older subjects (age 55- 70 years of age) were not associated.
This study found that elevated PP was associated with increased cerebrospinal fluid P-tau and decreased Aβ1-42 in older subjects with normal cognitive function, suggesting that pulsatile hemodynamics may be associated with amyloidosis and tau protein-related neurodegeneration. the relationship between PP and cerebrospinal fluid biomarkers was age-dependent and could only be found in subjects aged 40- -60 years old subjects.