Lifelong cognitive reserve as a resilience factor for frailty progression and recovery in later life

The cognitive reserve reflects the cumulative cognitive enrichment across the life course and has been linked to resilience against cognitive decline and dementia. However, its role in shaping the dynamic course of physical frailty, including both progression and recovery, remains insufficiently understood. We aimed to examine the associations between lifelong composite cognitive reserve and transitions across frailty states and mortality among older adults in China.

A longitudinal study was conducted using the data from 13,256 older adults from the Chinese Longitudinal Healthy Longevity Survey (mean age: 88.14 years; women: 59.00%; median follow-up duration: 6.00 years). A combined cognitive reserve Z-score was developed using early-life educational attainment, midlife occupational complexity, and late-life leisure activities. Frailty was operationalized using the FRAIL scale and reversion was measured by transitions from frailty at baseline to non-frailty during follow-up. Multi-state Markov models were performed to estimate the effects of the cognitive reserve on transitions among non-frail, pre-frail, frail, and death. Fine-Gray competing risks models were used to estimate the cognitive reserve associated with the risk of frailty and likelihood of reversion.

A higher cognitive reserve was associated with lower hazards of progression from non-frail to pre-frail (HR = 0.95; 95% CI 0.92-0.98), pre-frail to frail (HR = 0.95; 95% CI 0.90-1.00), and from all frailty states to death (HR = 0.91-0.97). A greater cognitive reserve increased the likelihood of recovery from pre-frailty to non-frailty (HR = 1.07; 95% CI 1.03-1.10). Fine-Gray competing risks models showed that a higher cognitive reserve was associated with reduced risk of developing frailty (SHR = 0.97; 95% CI = 0.94-0.99) and increased likelihood of reversion (SHR = 1.28; 95% CI = 1.22-1.33).

A higher cognitive reserve is linked to a decreased risk of developing frailty, slower progression, and a greater likelihood of improvement from pre-frailty to non-frailty, suggesting that lifelong cognitive enrichment enhances the physiological reserve beyond cognition. These findings suggest that interventions and policies that support the development of cognitive reserve across the life course may contribute to healthier frailty trajectories in later life.