UC San Diego

Objective

The current study examined the association between pulse pressure (PP) and CSF-based biomarkers for Alzheimer disease, including β-amyloid 1-42 (Aβ1-42) and phosphorylated tau (P-tau) protein, in cognitively normal older adults.

Methods

One hundred seventy-seven cognitively normal, stroke-free older adult participants (aged 55-100 years) underwent blood pressure assessment for determination of PP (systolic - diastolic blood pressure) and lumbar puncture for measurement of CSF Aβ1-42 and P-tau. Pearson correlations and multiple linear regression, controlling for age, sex, APOE genotype, and body mass index, evaluated the relationship between PP and Alzheimer disease biomarkers.

Results

PP elevation was associated with increased P-tau (r = 0.23, p = 0.002), reduced Aβ1-42 (r = -0.19, p = 0.01), and increased P-tau to Aβ1-42 ratio (r = 0.27, p < 0.001). After controlling for covariates, PP remained associated with P-tau (β = 0.18, p = 0.0196) and P-tau to Aβ1-42 ratio (β = 0.0016, p < 0.001) but was no longer associated with Aβ1-42 (β = -0.1, p = 0.35). Post hoc multivariate analyses indicated that increased PP was associated with all biomarkers in younger participants (aged 55-70 years) (Aβ1-42: p = 0.050; P-tau: p = 0.003; P-tau to Aβ ratio: p = 0.0007) but not older participants (aged 70-100 years).

Conclusions

PP elevation is associated with increased CSF P-tau and decreased Aβ1-42 in cognitively normal older adults, suggesting that pulsatile hemodynamics may be related to amyloidosis and tau-related neurodegeneration. The relationship between PP and CSF biomarkers is age-dependent and observed only in participants in the fifth and sixth decades of life.