Relationships of Cerebral Perfusion with Gait Speed across Systolic Blood Pressure Levels and Age: a Cohort Study.

BACKGROUND: This study aimed to examine if the association of cerebral perfusion with gait speed differs across systolic blood pressure (SBP) and age.

METHODS: Cerebral perfusion was measured via arterial spin-labelled (ASL)-MRI among community-dwelling adults aged 31-94 years in the population-based Mayo Clinic Study of Aging. Usual gait speed was assessed over 5.6 meters on an electronic mat. Sex- and BMI-adjusted linear regression models estimated cross-sectional gait speed associations with ASL and modifying effects of age and SBP using 3-way and 2-way interaction terms between continuous age, SBP, and ASL. Results report estimated differences in gait speed per standard deviation (SD) lower ASL for exemplar SBPs and ages.

RESULTS: Among 479 participants (mean age 67.6 years; 44% women; mean gait speed 1.17m/s), ASL relations to gait speed varied by age (ASL-x-age interaction: p=0.001) and SBP (ASL-x-SBP interaction: p=0.009). At an SBP of 120mmHg, each SD lower ASL was associated with a 0.04 m/s (95% CI: 0.01,0.07) slower gait speed at 65 years, 0.07 m/s (0.04,0.10) at 75 years, and 0.09 m/s (0.05,0.13) at 85 years. At an SBP of 140 mmHg, ASL associations with gait speed were attenuated to 0.01 (-.01,0.04), 0.04 (0.02,0.06) and 0.06 (0.04,0.09) m/s slower gait speed at ages 65, 75 and 85, respectively.

CONCLUSION: Poorer cerebral perfusion is associated with clinically meaningful slower gait speeds, particularly with older age, while higher perfusion markedly attenuates age differences in gait speed.