Abstract
The heart rate response/recovery (HRR) index, a common indicator for cardiovascular health during exercise, has been linked with neurocognitive disorders and mortality. However, the relationship between HRR index and dementia remains unknown. Electrocardiogram data from 46,348 middle-aged and older adults from the UK Biobank were analyzed following a standardized submaximal exercise stress test (15-second baseline, 6-minute exercise, and 1-minute recovery). The HRR index was calculated as the product of heart rate responses ratio during exercise (peak/resting heart rate) and recovery ratio (peak/recovery heart rate). We found that 519 participants were ascertained with dementia, including 232 with Alzheimer’s disease (AD) and 85 with vascular dementia (VaD) during a median follow-up period of 12.62 years. Higher HRR index and recovery ratio were significantly associated with a reduced risk of all-cause dementia (HR: 0.72, 95% CI: 0.54-0.94, P = 0.017; HR: 0.75, 95% CI: 0.57-0.99, P = 0.018), but not with incident AD or VaD, respectively. In addition, higher HRR index was significantly correlated with slower cognitive decline in processing speed, reasoning, and memory (β:2.39, 95% CI: 0.28-4.49, P = 0.027; β: 2.12, 95% CI: 0.26-4.00, P = 0.027; β: 0.03, 95% CI: 0.02-0.05, P < 0.001), while the recovery ratio was significantly correlated with slower cognitive decline in reasoning and memory (β: 1.91, 95% CI: 0.04-3.79, P = 0.045; β: 0.03, 95% CI: 0.01-0.04, P < 0.001). Higher HRR index and recovery ratios are associated with a decreased risk of incident dementia and appear to have beneficial effects on delaying cognitive decline. The possible mechanisms for this may involve autonomic function and neurovascular health.