Albumin, Hemoglobin, and the Trajectory of Cognitive Function in Community-Dwelling Older Japanese: A 13-Year Longitudinal Study.

BACKGROUND: Cognitive function can substantially decline over a long period, and understanding the trajectory of cognitive function is important. However, little is known about the linkage between nutritional biomarkers and long-term cognitive change.

OBJECTIVES: We analyzed 13-year longitudinal data for older Japanese to examine the associations of serum albumin and hemoglobin levels with the trajectory of cognitive function.

DESIGN: Longitudinal study.

SETTING: Community-based.

PARTICIPANTS: A total of 1,744 community-dwelling adults aged 65 years or older who participated in annual health examinations in Kusatsu town, Gunma Prefecture, Japan, from 2002-2014.

MEASUREMENTS: Cognitive function was assessed annually by the Mini-Mental State Examination (MMSE). Albumin and hemoglobin levels at baseline (the year when a respondent first participated in the health examination) were divided into quartiles. Hierarchical linear modeling was used to analyze intrapersonal and interpersonal differences in cognitive function.

RESULTS: Participants' MMSE scores decreased at an accelerated rate over the 13-year period. Participants with the lowest baseline albumin level (below the first quartile line) showed a greater accelerated decline in MMSE scores over time, compared with those with the highest level (above the third quartile line). Moreover, MMSE scores in participants with a lower hemoglobin level and lower MMSE score at baseline tended to decline faster over time at an accelerated rate.

CONCLUSIONS: These findings yield new insights about the complex and diverse roles of these nutritional biomarkers on the trajectory of cognitive function in old age.