Background: Resting heart rate (RHR) is an easily measured marker that is independently associated with cardiovascular disease (CVD) risk. There are several potential mechanisms by which RHR could affect cognitive function, but little is known about the relation of RHR and cognitive decline. We examined the association of RHR with 20 year cognitive decline in a community-based cohort.
Methods: We studied 13,720 middle-aged white and black participants without a prior history of stroke or atrial fibrillation. RHR was obtained from a 12-lead resting electrocardiogram at baseline (1990-1992). Cognitive testing was measured at baseline and at up to two additional visits (1996-1998 and 2011-2013). A 3-test combined cognitive score was summed from these tests: delayed word recall, digit symbol substitution and word fluency. RHR was categorized into groups as < 60 (reference), 60-69, 70-79 and ≥80 bpm. We examined the association of RHR with cognitive decline using linear mixed-effects models adjusted for demographic, socioeconomic, CVD risk factors, and AV nodal blockade use. ApoE genotype was included as a possible predictor. Imputation methods were used to account for attrition over follow-up.
Results: Mean (SD) age of participants at baseline was 58 (6) years; 56% were women, 24% black. Average (SD) RHR was 66 (10) bpm, with RHR distribution: <60 (28%), 60-69 (40%), 70-79 (23%), >80 (9%) bpm. Over a mean follow-up of 20 years, participants in each RHR group exhibited cognitive decline (Table Part A). However, there was relatively greater global cognitive decline for those with RHR 70-79 and >80 bpm compared to <60 bpm (Part B). Results were consistent when excluding participants on AV nodal blockade medications.
Conclusion: Elevated RHR is independently associated with greater cognitive decline over 20 years. Further studies are needed to determine whether the association is causal or secondary to another underlying process. If causal, future studies can determine whether modification of RHR can reduce cognitive decline.