Clinical and scientific investigations in the field of dementia expanded greatly in the past two decades. Medline citations that addressed Alzheimer disease (AD), the most common dementing disorder, rose from 78 in 1980 to 987 in 1990 and to 1772 in 2000. Underscoring this increased body of knowledge, three practice parameters on dementia were published in 2001 by the Quality Standards Subcommittee of the American Academy of Neurology. Although some older studies are included for context, this review focuses on selected recent advances in dementia that are relevant for the practicing physician. Topics covered include: 1) diagnosis of dementia; 2) risk factors and biomarkers; 3) mild cognitive impairment; 4) the scientific basis for treatment advances in AD; and 5) other dementing disorders.