Blood pressure and Alzheimer's disease biomarkers in cognitively unimpaired adults: a multicenter study.

Background: Hypertension is a modifiable risk factor for dementia, potentially influencing Alzheimer's disease (AD) pathology. Understanding this relationship is essential for developing interventions to reduce dementia risk.

Objectives: We investigated cross-sectional and longitudinal associations between blood pressure and AD biomarkers in cerebrospinal fluid (CSF) and amyloid (Aβ) positron emission tomography (PET) in cognitively unimpaired adults.

Design: Prospective observational study.

Setting: We analyzed data from cognitively unimpaired participants from three observational prospective European studies: ALFA+ (NCT02485730), EPAD-LCS (NCT02804789), and AMYPAD PNHS (EudraCT: 2018-002,277-22).

Measurements: ALFA+ participants had either CSF biomarkers (CSF Aβ42, Aβ40, p-tau181, t-tau) and/or Aβ PET data. EPAD participants had CSF biomarkers (CSF Aβ42, p-tau181, t-tau), and AMYPAD participants had Aβ PET data. All participants had available data about diabetes, use of hypertensive medication, and waist-to-hip ratio. Multivariable linear regression models were used to analyze cross-sectional associations between systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) with CSF biomarkers or Aβ PET (Centiloid units, CL); longitudinal associations were tested by means of delta CL scores between baseline and follow-up to assess Aβ PET changes over time.

Results: We included 405 participants from ALFA+ (mean age 61.1 years; 60 % female), 1104 from EPAD (mean age 64.8 years; 59.1 % female), and 340 from AMYPAD (mean age 71.8 years; 60 % female). In ALFA+, DBP was negatively associated with CSF Aβ40 (p = 0.016) and p-tau181 (p = 0.050), while there was a non-significant trend towards a positive association between SBP and CL over time (p = 0.058). In EPAD, DBP was negatively associated with CSF Aβ42 (p < 0.001) and p-tau181 (p = 0.014), while PP was positively associated with CSF Aβ42 (p = 0.024). In AMYPAD, SBP (p = 0.002) and PP (p = 0.003) were positively associated with CL at baseline, with a similar non-significant trend being found for DBP (p = 0.089). Higher DBP (p = 0.042) was significantly associated to increased CL over time, with a similar non-significant trend being found for SBP (p = 0.072). We did not find significant associations between blood pressure and longitudinal changes in CSF biomarkers.

Conclusions: Elevated blood pressure was associated with increased Aβ PET accumulation in cognitively unimpaired individuals. Further research is warranted to elucidate potential mechanisms underlying the negative associations between DBP and CSF biomarkers, which do not reflect the typical AD molecular signature. These findings highlight the relevance of high blood pressure as a potential risk factor for cognitive decline.