Objective: The reserve hypothesis accounts for the lack of direct relationship between brain pathology and its clinical manifestations. Research has mostly focused on cognition; our objective is to examine whether the reserve hypothesis applies to motor function. We investigated whether education, a marker of reserve, modifies the association between white matter lesions (WMLs), a marker of vascular brain damage, and maximum walking speed (WS), an objective measure of motor function. We also examined the cross-sectional and longitudinal association between education and WS.Methods: Data are from 4,010 participants aged 65-85 years in the longitudinal Three-CityDijon Study with up to 4 WS measures over 10 years. We examined the interaction between education and WMLs for baseline WS. We studied the association between education and repeated WS measures using linear mixed models, and the role of covariates in explaining the education-WS association.Results: Education was strongly associated with baseline WS; the difference in mean WS between the high and low education groups (0.145 m/s, 95% confidence interval 5 0.125-0.165) was equivalent to 7.4 years of age. WMLs were associated with slow WS only in the low education group (p interaction 5 0.026). WS declined significantly over time (20.194 m/s/10 years, 95% confidence interval 5 20.206, 20.182), but education did not influence rate of decline. Anthropometric characteristics, parental education, general health, and cognition had the strongest role in explaining the baseline education-WS association.Conclusions: Participants with more education were less susceptible to WMLs' effect on motor function. Higher education was associated with better motor performances but not with motor decline. These results are consistent with the passive reserve hypothesis. The concept of brain reserve accounts for the lack of direct relationship between brain pathology and its clinical manifestations.1-3 High reserve, assessed via anatomical features of the brain or markers of enriched environments (e.g., education, socioeconomic status [SES]), has been associated with reduced clinical manifestations of neuropathologic changes. [4][5][6] Risk factors have also been found not to be related to the same extent to functional measures among those with high and low reserve. 7,8 Recent evidence suggests that higher education is strongly associated with better cognitive performances but not with a slower rate of cognitive decline.9-12 These findings are interpreted as supporting a "passive reserve" hypothesis: higher education is associated with better performances because of the persistence of earlier differences rather than differential rates of cognitive decline. In longitudinal studies, this translates into baseline