["Geriatrics &Gerontology International, Volume 26, Issue 5, May 2026. ", "\nThis study emphasized that cognitive impairment showed a stronger link to frailty progression than vice versa. Targeting key modifiable risk factors, such as poverty, illiteracy, multimorbidity, hearing loss, and sleep problems, may help delay cognitive impairment and frailty, particularly among older women.\n\nABSTRACT\n\nBackground\nCognitive impairment and frailty are prevalent in older adults, yet their longitudinal interplay and determinants remain underexplored, particularly in Chinese populations. This study aims to characterize the trajectories of cognitive function and frailty, examine their bidirectional associations, and identify the risk factors driving their progression.\n\n\nMethods\nWe analyzed data from 4805 adults aged ≥ 65 years from the Chinese Longitudinal Healthy Longevity Survey (2011–2018). Cognitive function was assessed using the Chinese Mini‐Mental State Examination, and frailty status was measured according to the modified Fried criteria. Group‐based trajectory modeling was applied to identify longitudinal patterns, and trajectories were named according to validated cutoff values. Dual‐trajectory analysis was employed to examine their interrelationships, and multinomial logistic regression was utilized to identify predictors of adverse trajectories.\n\n\nResults\nThree cognitive trajectories were identified: stably high cognition (82.6%), progressive cognitive decline (12.3%), and persistently low cognition (5.1%). Five frailty trajectories were found: non‐frail (48.1%), fluctuating pre‐frailty (17.2%), reversible frailty (6.9%), progressive frailty (11.4%), and stable frailty (16.4%). Cognitive impairment was more strongly associated with frailty progression than the reverse. Advanced age and female sex were shared risk factors for adverse trajectories. Among those with cognitive impairment, poverty and multimorbidity were associated with adverse frailty. Among frail participants, illiteracy, hearing loss, and poor sleep increased the risk of cognitive decline.\n\n\nConclusions\nThis study emphasized that cognitive impairment showed a stronger link to frailty progression than vice versa. Targeting key modifiable risk factors, such as poverty, illiteracy, multimorbidity, hearing loss, and sleep problems may help delay cognitive impairment and frailty, particularly among older women.\n\n"]