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Objective: To identify approximately 500 cases of incident cognitive impairment (ICI) in a large, national sample adapting an existing cognitive test-based case definition and to examine relationships of vascular risk factors with ICI. Method: Participants were from the REGARDS study, a national sample of 30,239 African-American and White Americans. Participants included in this analysis had normal cognitive screening and no history of stroke at baseline, and at least one follow-up cognitive assessment with a three-test battery (TTB). Regression-based norms were applied to TTB scores to identify cases of ICI. Logistic regression was used to model associations with baseline vascular risk factors. Results: We identified 495 participants with ICI of 17,630 eligible participants. In multivariable modeling, income (OR 1.83 CI 1.27,2.62), stroke belt residence (OR 1.45 CI 1.18,1.78), history of transient ischemic attack (OR 1.90 CI 1.29,2.81), coronary artery disease(OR 1.32 CI 1.02,1.70), diabetes (OR 1.48 CI 1.17,1.87), obesity (OR 1.40 CI 1.05,1.86), and incident stroke (OR 2.73 CI 1.52,4.90) were associated with ICI. Conclusions: We adapted a previously validated cognitive test-based case definition to identify cases of ICI. Many previously identified risk factors were associated with ICI, supporting the criterion-related validity of our definition.

The influence of aspect on water yield variability over a long period, 1936-1964, was studied at two small, mountainous watersheds within the Davis County Experimental Watershed near Farmington, Utah. North-facing Miller Creek is densely vegetated by a conifer-aspen forest and mountain brush. Miller Creek's yield was more variable for daily, monthly, seasonal, and annual flows than yields from south-west facing Halfway Creek which is covered by mountain brush. Differences between watersheds in annual yield and snowmelt season runoff were nonsignificant. The snowmelt runoff season extended for an average of 65 days on both watersheds, but it began 24 days earlier (March 29) on Halfway. Approximately 57 percent of the mean annual flow of 19.4 inches on Halfway, and 68 percent of Miller's mean annual yield of 17.9 inches occurred during the snowmelt runoff season. One-third of Halfway's annual flow and one-half of Miller's occurred during the May 15 to September 15 growing season when only one-fifth of the annual precipitation of 42 inches usually fell. The difference between the growing season flows from the two watersheds was significant, with Miller's flow greater by 3.4 inches.