Physical Performance Moderates the Association Between Age and Executive Function in Older Adults at Elevated Risk of Dementia: Cross‐Sectional Analysis From the CITA GO‐ON Trial

ABSTRACT Background Preservation of executive function is vital for independence and dementia prevention, yet the physical performance levels at which age‐related executive vulnerability becomes detectable remain uncertain. This study examined whether gait speed, handgrip strength and leg muscle power influence the relationship between age and executive function in older adults at increased dementia risk and assessed how sex and white matter hyperintensity (WMH) burden affect this relationship. Methods Cross‐sectional analysis of 920 community‐dwelling older adults (aged 60–85) at high dementia risk, enrolled in the CITA GO‐ON trial. Executive function was measured by the Trail Making Test (TMT B minus A) and the Stroop interference score. Physical performance included gait speed, handgrip strength and peak leg muscle power. Moderation analyses tested whether physical performance moderated the age–executive function association, adjusting for sex, socioeconomic status, depressive symptoms, cardiometabolic conditions, BMI and smoking; three‐way interactions tested sex effects. The Johnson–Neyman technique identified regions of significance, the range of performance values over which the age–executive function association was statistically detectable. Sensitivity analyses included cognitively healthy participants and WMH adjustment. Results The average (SD) age was 69.5 (6.2) years; 48.4% were female, and average education was 13.0 (4.5) years. At baseline, 63 participants (6.8%) had mild cognitive impairment. Gait speed ( β = −0.27, p < 0.05), handgrip strength ( β = −0.08, p < 0.05) and peak leg muscle power ( β = −0.007, p < 0.05) moderated the age–executive function link. Johnson–Neyman regions‐of‐significance were located in the upper range of the performance distribution. For TMT B minus A, the age–executive function association was statistically detectable below gait speed 1.83 m/s, handgrip 48.8 kg and leg power 438 W (1.0%–4.8% of participants), whereas for Stroop interference the corresponding values were lower (gait 1.68 m/s, handgrip 43.9 kg, leg power 366 W; up to 15.9% of participants). In sex‐stratified analyses, gait speed moderated the age–executive function association for TMT B minus A in males and for Stroop interference in females. WMH burden was not independently associated with executive function. Conclusions In older adults at increased dementia risk, higher physical performance was associated with a weaker relationship between age and executive function, independent of socioeconomic, emotional, body composition and cardiovascular factors. This moderation was most consistent for gait speed, with a sex pattern that differed by outcome. Longitudinal studies are needed to test whether maintaining high physical performance helps preserve executive function and inform preventive strategies.