In 1998-1999, dementia was classified in 3602 CHS participants as a part of the CHS Cognition Study.29,30 Inclusion in the CHS-Cognition cohort required completion of cranial magnetic resonance imaging (MRI) and the modified Mini-Mental State Examination (MMSE) in 1992-1994. These participants were screened using data collected at the visit closest to MRI to identify those at higher risk who were asked to return to the clinic for additional cognitive testing. An individual was considered to be at high risk for dementia if he or she had previously scored less than 80 or had a decrease of 5 or more points on the modified MMSE administered at previous examinations, a previous Telephone Interview for Cognitive Status score of less than 28 or an Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) score of greater than 3.6, incident stroke, or current residence in a nursing home. A battery of neuropsychiatric tests was administered to those agreeing to return to the clinic or to receive a home visit. The following examinations were used: the American version of the National Reading Test, Raven's Colored Progressive Matrices, California Verbal Learning Test, Rey-Osterreith Figure, immediate and delayed recall, modified Boston Naming Test, verbal fluency test, block design (modified from the Wechsler Adult Intelligence Scale–Revised), Stroop Neuropsychological Screening Test, Trail Making Test, digit spans, and Baddeley and Papagno divided attention task. Methods to evaluate persons who declined the neuropsychiatric battery or who were no longer living included a medical record review of all hospitalizations, questionnaires sent to the personal physician, and standardized interviews by telephone with the participants (if living) or a designated informant (Telephone Interview for Cognitive Status, Neuropsychiatric Inventory, or IQCODE). In addition, all prospectively collected data from inception of the CHS were reviewed to provide additional information on cognitive decline during the 10 years of follow-up, including repeated measures of the modified MMSE, Digit Symbol Substitution Test, Benton Visual Retention Test, Trails A and B, Center for Epidemiologic Studies Depression Scale, medications inventory, activities of daily living, instrumental activities of daily living, other physical function measures (gait speed, balance tests, grip strength, etc), and documentation of hospitalized medical events, such as strokes, myocardial infarctions, etc. All data were compiled into packets for review during the classification process.