Biomarkers, dementia, and public health.

Public health is defined as the organized efforts of society to improve health. This is often framed in terms of prevention, with primary, secondary, and tertiary prevention representing, respectively, fundamental prevention through understanding of causation, to alteration of natural history, through understanding of pathophysiological mechanisms and palliation. Biomarkers play a role in all of these levels of prevention of dementias. The clearest application of biomarkers from a public health perspective is in the setting of screening. Screening has particular meaning for public health and includes early detection as a core element, coupled with treatments or preventative actions to reduce the burden of disease. Here, we will cover the range of evidence required if biomarkers are to play a part in population prevention of dementia, including scientific and technical aspects together with ethical, legal, and social considerations. Ensuring research activity that addresses these wider perspectives is essential.