Visit-to-Visit Blood Pressure Variability and CSF Alzheimer Disease Biomarkers in Cognitively Unimpaired and Mildly Impaired Older Adults

Background and Objectives

Blood pressure variability is an emerging risk factor for cognitive decline and dementia, but mechanisms remain unclear. The current study examined whether visit-to-visit blood pressure variability is related to CSF Alzheimer disease biomarker levels over time and whether associations differed by APOE 4 carrier status.

Methods

In this retrospective analysis of a prospective cohort study, cognitively unimpaired or mildly impaired older adults from the Alzheimer’s Disease Neuroimaging Initiative underwent 3 to 4 blood pressure measurements over a 12-month period and ≥1 lumbar puncture for evaluation of CSF phosphorylated tau, total tau, and β-amyloid levels at follow-up (6–108 months later). APOE 4 carriers were defined as having ≥1 4 allele. Visit-to-visit blood pressure variability was determined over 12 months as variability independent of mean. Only CSF samples collected after the final blood pressure measurement were analyzed. Bayesian linear growth modeling investigated the role of blood pressure variability, APOE 4, and the passage of time on CSF biomarker levels after controlling for several variables, including average blood pressure and baseline hypertension.

Results

Four hundred sixty-six participants (mean 76.7 [SD 7.1] years of age) were included in the study. Elevated blood pressure variability was associated with increased CSF phosphorylated tau (β = 0.81 [95% CI 0.74, 0.97]), increased total tau (β = 0.98 [95% CI 0.71, 1.31]), and decreased β-amyloid levels (β = –1.52 [95% CI –3.55, –0.34]) at follow-up. APOE 4 carriers with elevated blood pressure variability had the fastest increase in phosphorylated tau levels (β = 9.03 [95% CI 1.67, 16.36]). Blood pressure variability was not significantly related to total tau or β-amyloid levels over time according to APOE 4 carrier status.

Discussion

Older adults with elevated blood pressure variability exhibit increased CSF phosphorylated tau, increased total tau, and decreased β-amyloid over time, suggesting that blood pressure variability may correlate with alterations in Alzheimer disease biomarkers. Findings warrant further study of the relationship between blood pressure variability and the development of Alzheimer disease. APOE 4 carrier status moderated relationships between blood pressure variability and CSF phosphorylated tau but not total tau or β-amyloid, consistent with other studies relating hemodynamic factors to tau changes.

Read article at journal's website

Related Articles

Responses

Your email address will not be published.