The Relationship Between Brain Frailty and Physical Function in Patients With Stroke Undergoing Rehabilitation.

Background Brain frailty has gained attention as a predictor of poor functional outcomes. However, the relationship between brain frailty and physical function among patients with stroke undergoing rehabilitation remains unclear. This study aimed to investigate the relationship between brain frailty and activities of daily living (ADLs) at discharge among patients with stroke admitted to a convalescent rehabilitation ward. Methods This single-center retrospective cohort study included patients with stroke admitted to the convalescent rehabilitation ward. Brain frailty (i.e., white matter hyperintensity, old vascular lesions, and brain atrophy) was evaluated using cranial magnetic resonance imaging at stroke onset. The outcome measure was defined as ADLs at discharge, assessed using the motor item of the Functional Independence Measure (FIM-M). Multiple regression and mediation analyses were performed to assess the association between brain frailty scores and FIM-M scores at discharge. Results The final analysis included 160 patients (median age: 73.0 years; interquartile range: 64.0-80.0 years; male: n = 90, 56.2%). The multiple regression analysis revealed that severe brain frailty (score of 3) was significantly associated with FIM-M scores at discharge, even after adjusting for covariates (β = -0.18; p = 0.041). Furthermore, mediation analysis revealed that severe brain frailty was associated with FIM-M scores at discharge through the mediation of cognitive function (total effect = -16.20; p < 0.001). Conclusions Brain frailty may provide new insights for outcome prediction in stroke rehabilitation, highlighting the importance of incorporating its assessment into routine clinical practice.