Cardiorespiratory Fitness And Dementia Risk In Older Adults

Brain health is closely linked to cardiovascular health, with evidence suggesting that enhancing cardiorespiratory fitness (CRF) may reduce dementia risk. While CRF is linked to dementia risk, it is still unclear whether changes in CRF over time can influence this risk. PURPOSE: This study aims to assess the relationship between baseline CRF, changes in CRF, and all-cause dementia in a cohort of cognitively healthy men and women aged 70-77. METHODS: Participants were recruited from Trondheim, Norway, as part of the Generation 100 Study, the largest randomized exercise trial on older adults. Participants’ CRF levels were measured at baseline in 2012 and at 1-year follow-up in 2013. Dementia outcomes were determined through hospital records, with follow-up starting from the 1-year test date and ending on December 31, 2021. Cox proportional hazard regression analysis assessed the association between CRF and dementia, adjusting for sex, age and cohabitation status. RESULTS: Among a total of 1170 participants (mean age 72.3. ± 2.0, 49.9% women), 87 participants developed dementia over a mean follow-up time of 7.9 ± 1.17 years. Mean baseline CRF was 29.5 ± 6.4 mL/kg/min (men: 32.1 ± 6.5; women: 26.8 ± 4.9, p < 0.001). Participants who later developed dementia had lower baseline CRF than those who remained healthy (28.2 ± 6.1 vs. 29.6 ± 6.4, p = 0.043), with each unit higher baseline CRF associated with a 4% reduced dementia risk (HR: 0.96, 95% CI: 0.93-1.00). After one year of exercise, CRF increased by 1.6 ± 3.5 mL/kg/min across all participants, with similar increases in both those who later developed dementia (1.9 ± 4.0), and those who stayed healthy (1.6 ± 3.5) (p = 0.128). Having baseline CRF above the sex-specific average at baseline was associated with a 37% lower dementia risk (HR: 0.63, 95% CI: 0.41-0.98). No significant association was found for 1-year CRF (HR: 0.97, 95% CI: 0.63-1.50). Neither was maintaining or increasing to CRF above this threshold following one year of exercise (HR: 0.74, 95% CI: 0.45-1.20; HR: 1.34, 95% CI: 0.77-2.32, respectively). CONCLUSIONS: Baseline CRF may predict dementia risk, with protective effects observed at CRF levels above 32.1 mL/kg/min for men and 26.8 mL/kg/min for women. Short-term changes in CRF did not influence dementia risk.