Nutritional biomarkers and subsequent cognitive decline among community-dwelling older Japanese: a prospective study

Micronutrients are associated with dementia and cognitive decline among older adults. However, nutritional biomarkers of such decline have not been identified. We attempted to identify nutritional biomarkers that were independent risk markers of cognitive decline in a population of older Japanese.

Among 873 cognitively intact adults aged 70 years or older at baseline, 682 (mean age [standard deviation], 75.5 [4.4] years; women 59.7%) were followed for a period of up to 4 years, and nutritional biomarkers in a blood panel were assessed, namely, red blood cell count, hematocrit, mean corpuscular volume, hemoglobin, total cholesterol, high-density lipoprotein cholesterol, hemoglobin A1c, creatinine, albumin, blood glucose, γ-glutamyl transpeptidase, triglyceride, and white blood cell count. Cognition was assessed by the Mini-Mental State Examination, and cognitive decline was defined as a decrease of at least three points on the Mini-Mental State Examination.

During an average follow-up of 2.7 years, 115 adults (16.9%) developed cognitive decline. After controlling for important confounders, the odds ratios for cognitive decline in the lowest and middle tertiles of red blood cell count were 2.62 (95% confidence interval: 1.44-4.74) and 2.18 (1.20-3.96), respectively, as compared with the highest tertile. The corresponding odds ratios were 1.81 (1.05-3.22) and 1.03 (0.58-1.83), respectively, for high-density lipoprotein cholesterol and 2.06 (1.14-3.77) and 1.02 (0.54-1.94) for albumin.

Low red blood cell count, high-density lipoprotein cholesterol, and albumin were independent risk markers for subsequent cognitive decline in a general population of older adults and may be useful in early clinical screening.