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Nonlinear association between pulse wave velocity and cognitive function: a population-based study

Nilsson, Erik D.a; Elmståhl, Sölveb; Minthon, Lennarta; Nilsson, Peter M.c; Pihlsgård, Matsb; Tufvesson, Evaa; Nägga, Katarinaa

Journal of Hypertension:
doi: 10.1097/HJH.0000000000000329
ORIGINAL PAPERS: Epidemiology
Abstract

Background: Arterial stiffness has been hypothesized to contribute to cognitive decline. However, previous studies have reported inconsistent results. The aim of this cross-sectional study was to investigate the association between carotid–femoral pulse wave velocity (cfPWV), a marker of arterial stiffness, and cognitive function.

Methods: The study population comprised 2637 individuals from the population-based Malmö Diet and Cancer Study (mean age 72.1 years, 60.8% women). During the follow-up examinations between 2007 and 2012, cfPWV and results on the a quick test of cognitive speed (AQT) and Mini Mental State Examination (MMSE) cognitive tests were measured.

Results: After adjustments for demographics and traditional cardiovascular risk factors, a linear association was found between cfPWV and AQT (B = 0.37; P = 0.039). On the basis of hypothesis that individuals with high cfPWV values have worse cognitive function than can be inferred from a linear association, cfPWV was dichotomized at the 90th percentile (the binary variable denoted cfPWV >13.8). When cfPWV >13.8 was added to the model, the linear association between continuous cfPWV and AQT disappeared (B = –0.08; P = 0.72), but cfPWV >13.8 was highly significant (B = 4.81; P = 0.004). In the adjusted model with MMSE as outcome variable, cfPWV >13.8 also reached a statistically significant effect.

Conclusion: Arterial stiffness was inversely associated with cognitive function in a nonlinear fashion, with individuals in the top decentile of cfPWV explaining the association. Results from linear regressions should thus be interpreted with caution because, even when statistical significance is reached, they can be explained by pronounced nonlinearity.

Author Information

aClinical Memory Research Unit, Department of Clinical Sciences, Lund University

bDivision of Geriatric Medicine, Department of Health Sciences

cDepartment of Clinical Sciences, Lund University, Skåne University Hospital, Malmö, Sweden

Correspondence to Erik D. Nilsson, MD, Clinical Memory Research Unit, Department of Clinical Sciences, Lund University, Simrisbanvägen 14, S-205 02, Malmö, Sweden. E-mail: erik.nilsson@med.lu.se

Abbreviations: AQT, a quick test of cognitive speed; cfPWV, carotid–femoral pulse wave velocity; MAP, mean arterial pressure; MDCS, Malmö Diet and Cancer Study; MMSE, Mini Mental State Examination; VCI, vascular cognitive impairment

Received 24 January, 2014

Revised 7 July, 2014

Accepted 7 July, 2014

© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins