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Annexes 212These findings should be interpreted by keeping in mind the fact that our sample is constitutedof a mixture of demented subjects, subjects in a pre-diagnosis phase of dementia, and subjectswith a normal cognitive aging since we included in this study all the subjects with at least oneneuropsychological evaluation during the follow-up. Thus, estimated cognitive declines anddifferential declines according to gender and the level of education represent declines in apopulation of elderly people whatever the type and the course of their cognitive aging process.Brain aging in a sample of subjects from the general population cumulates the proper effect ofage on the central nervous system, particularly on neurones and synapses, the effect ofAlzheimer lesions or other neurodegenerative lesions like Lewy bodies, and the effect ofcerebro-vascular lesions. All these morbid processes increase with age. From a practicalclinical point of view and a public health point of view, it would be relevant to separate theseprocesses to evaluate for instance the impact of gender and education separately on normalcognitive aging and on cognitive decline toward dementia. However, it appears also relevantto study the evolution of the whole sample because there is a great overlap in brain lesionsbetween demented and non demented subjects [13], there is a long progressing pre-dementiaphase and the stage of dementia remains more or less arbitrary defined. Moreover, it is verydifficult to study separately normal cognitive aging and especially to distinguish determinantsof normal aging from those of pathological aging because we cannot be sure that a sample ofnormal elderly does not include subjects in a pre-diagnosis phase of dementia [26]. As aconsequence, the association we observed between education and cognitive decline both onthe latent cognition and on the psychometric tests could be the result of the effect of educationon the risk of dementia [20], on the shape of the pre-diagnosis cognitive decline [1, 11, 25]and on the normal aging process [1, 8, 26]. On the other hand, the deeper cognitive decline ofwomen in older ages could be explained by a higher risk of dementia for the womencompared to men among the oldest subjects [6].14