Medial temporal lobe (MTL)/memory and frontal lobe (FL)/executive functions indexes are used to measure changes related to cognitive aging. These indexes are based on composite scores of neuropsychological tests validated in English-speaking populations, and their use in aging research is growing in popularity. This study aimed at validating the MTL/memory and FL/executive functions indexes in French-speaking adults. Ninety-eight healthy participants (32 young and 66 older adults) were tested on eight neuropsychological tests, three associated with MTL/memory functions and five associated with FL/executive functions. Factor analysis indicated that residual scores independent of age and associated with MTL/memory functions grouped under one factor, and residual scores associated with FL/executive functions grouped under another factor. Bootstrapping analysis with 1,000 resamples confirmed stability for seven neuropsychological tests. This study provides the first validation of the MTL/memory and FL/executive functions composite scores in French-speaking adults, which may be used to assess cognitive changes in aging research.