Both Alzheimer’s disease and vascular dementia are the result of disease processes that typically develop overseveral decades. Population studies have estimated that more than half of the risk for dementia is preventable orat least modifiable through behavioral adaptations. The association between these lifestyle factors and the risk ofdementia is most evident for exposure in midlife. However, habits formed in middle age often reflect a lifetime ofbehavior patterns and living conditions. Therefore, individuals who, for example, are able to maintain healthydiets and regular exercise during their middle years are likely to benefit from these cognition-protective habitsthey have practiced throughout their lives. For numerous adult diseases, significant risks can often be traced backto early childhood. Suboptimal conditions during the perinatal period, childhood and adolescence can increasethe risk of adult diseases, including stroke, heart disease, insulin resistance, hypertension and dementia. Thisreview aims at summarizing some of the evidence for dementia risks from a life-time perspective with the goal ofraising awareness for early dementia prevention and successful aging.