Abstract
Blood pressure (BP) is not steady. It varies over intervals from months to consecutive cardiac cycles and this variation contains meaningful information beyond mean BP. Variability over multiple clinic visits (VVV-BP) and during 24-hour ambulatory monitoring (ABPV) is positively related to risk of stroke and coronary artery disease and negatively associated with cognitive performance. Beat-to-beat BP variation, often quantified as low frequency variability (0.04-0.15 Hz, LF-BPV), is less well-studied. Here, we examine the relationship between LF-BPV and cognitive outcomes in 1953 participants from the Midlife in the US study.
Participants completed the Brief Test of Adult Cognition by Telephone (BTACT) from which we derived episodic memory (EMF) and executive function (EFF) factors and a composite index. With participants in the seated position, the continuous BP signal was recorded non-invasively with a Finometer. The resultant time series was submitted to Fourier-based spectral analysis to compute LF-BPV. Linear regression models estimated the associations with cognitive indices.
Systolic (LF-SBPV) and diastolic (LF-DBPV) were positively associated with EFF (b=0.073 ± 0.033, p = 0.02), EMF (b=0.079 ± 0.036, p = 0.04), and the composite index (b=0.101 ± 0.035, p = 0.004) after adjustment for age, sex, education, and income. Findings were similar for LF-DBPV.
This positive association is consistent with evidence demonstrating that LF BPV contributes to increased delivery of oxygenated blood to the brain and clearance of metabolic and cellular waste via the brain's glymphatic system and intramural periarterial drainage pathway, both of which contribute to superior cognitive performance.