Update on Major Neurocognitive Disorders.

Dementia is a syndrome characterized by a gradually progressive course that spans a continuum from preclinical symptoms to major impairment in two or more cognitive domains with functional decline. In this review, the author examines some of the more common dementia syndromes from among dozens of different diseases. Findings show that as the U.S. population continues to age, the number of Americans with dementia is expected to rise drastically over the next several decades. This upsurge will contribute to increased health care costs and will have a significant public health impact. Neurodegenerative disorders such as Alzheimer's disease, frontotemporal degeneration, and alpha-synucleinopathies (e.g., Lewy body disease and Parkinson's disease) are some of the more prevalent causes for dementia. In recent years, advancements in neuroimaging, understanding of genetic contributions and pathological changes, and the development of novel biomarkers have fueled clinical understanding of these disorders. However, substantial disease-modifying therapies are still lagging. The advent of future interventions hinges on the ability to discern the distinct clinico-pathologic profiles of the various dementia syndromes and to identify reliable biomarkers for utilization in clinical trials.