The effect of anemia and white matter hyperintensities (WMH) on cognitive impairment in patients with amnestic mild cognitive impairment (MCI)

Anemia and subcortical ischemic change might be associated with increased risks for cognitive impairment among the elderly. This study examined the associations among anemia, WMH and cognitive function in patients with amnestic MCI. We recruited 278 subjects with amnestic MCI from the Clinical Research Center for Dementia of South Korea (CREDOS), a hospital-based cohort study. A standardized neuropsychological battery, containing tests of language, visuospatial function, verbal memory and executive function, was used for all patients. Anemia was defined as a hemoglobin concentration below 12 g/dl for women and below 13 g/dl for men. The severity of WMH was also examined using brain magnetic resonance imaging (MRI). After multivariable adjustments, anemia and WMH were associated with poorer performance on cognitive function tests (anemia: Stroop test, F = 4.17, p = 0.042; WMH: Stroop test, F = 6.45, p = 0.002; Rey-complex figure test-copy, F = 4.08, p = 0.018). Moreover, a significant interaction between anemia and the severity of WMH was observed in performance on the Go/no go test (F = 4.50, p = 0.012) and the Stroop test (F = 3.36, p = 0.037). In post hoc analysis, anemic patients with severe WMH had significantly worse scores on measure of executive function (Go/no go test, p = 0.011; Stroop test, p = 0.001). Anemia and WMH had interactive effects on executive function impairment among the elderly with amnestic MCI.