Associations of malnutrition and hydration status with cognitive frailty in older adults

Cognitive frailty (CF), defined as the coexistence of physical frailty and cognitive impairment without dementia, is a potentially reversible geriatric syndrome. Although malnutrition and dehydration are considered modifiable contributors, their relative roles in CF remain unclear.

Adults aged ≥65 years who underwent comprehensive geriatric assessment were included. CF was defined using Fried's frailty criteria and cognitive test scores (MoCA or MMSE). Nutritional status was assessed using the Mini Nutritional Assessment (MNA), and hydration status was evaluated by calculated plasma osmolarity. Age-, sex-, and Charlson Comorbidity Index comparisons were performed using 1:1 propensity score matching. Longitudinal changes in CF and nutritional status were examined in participants with follow-up data.

Among 232 individuals with CF, malnutrition and dehydration were present in 31.3% and 32.9%, respectively. After matching, malnutrition remained significantly more prevalent in the CF group than in robust controls (32.9% vs. 2.9%, p<0.001), whereas hydration status did not differ. Malnutrition was independently associated with lower body mass index, hypoalbuminemia, higher frailty, dysphagia, and poorer functional status (p<0.05). Although malnutrition and dehydration frequently coexisted, no significant association was observed. Longitudinal analyses showed that improvement in nutritional status was associated with CF resolution, while persistent CF was accompanied by declining MNA scores (p<0.05).

Malnutrition appears to be an important and potentially modifiable component of CF, whereas dehydration appears to play a more limited, stage-dependent role. Routine dysphagia screening, deprescribing of unnecessary medications, and caregiver education addressing increasing dependence in daily activities should be integral components of the management of CF.