Cognitive impairment is very common in advanced age, with dementia representing the main cause of disability in older adults. Over the past 20 years, several modifiable risk factors have been identified for dementia and Alzheimer's disease (AD), and many of them are shared with cardiovascular diseases. Given that the pathologic changes leading to dementia may start decades before dementia is diagnosed, it is crucial to adopt a life course approach when investigating risk factors for dementia. The CAIDE (Cardiovascular Risk Factors, Aging and Dementia) study is one of the first and still very few existing observational studies to have investigated the role of midlife risk factors for the subsequent development of dementia and AD in late life. The CAIDE study is built on the North Karelia Project, enabling risk factor assessment 20 to 30 years before the dementia diagnosis. The CAIDE study has revealed that late-life dementia and AD are heterogeneous and multifactorial disorders, suggesting that multidomain interventions targeting several risk factors simultaneously may be needed for optimal preventive effects. The FINGER (Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability) study is the first large long-term multidomain lifestyle intervention showing effect on prevention of cognitive impairment in at-risk elderly people. The study is conducted within the existing framework and builds on multidisciplinary prevention expertise following the North Karelia Project and CAIDE study. The FINGER study will, together with the ongoing multinational preventive initiatives, pave the way for pragmatic prevention programs and integrated interventions to facilitate healthy brain aging. This paper summarizes major findings on risk and protective factors for dementia and AD, and reviews key aspects and future directions in preventative strategies.