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The ratio of holotranscobalamin to total B12 is associated with cognitive impairment in elderly Latinos with elevated depression scores
Author(s) -
Garrod Marjorie G,
Green Ralph,
Allen Lindsay H,
Mungas Dan M,
Jagust William J,
Haan Mary N,
Miller Joshua W
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a155
Subject(s) - medicine , depression (economics) , confounding , cohort , odds ratio , gastroenterology , economics , macroeconomics
The percent of total plasma B12 bound to transcobalamin (holoTC/B12 ratio) may reflect availability of B12 to the nervous system. We analyzed associations between cognitive function and holoTC, total B12, and holoTC/B12 ratio in a cohort of elderly Latinos (n=1089; median age=70y, range=60–101y). Cognitive function was assessed by the modified mini‐mental state exam (3MSE), clinical cognitive impairment by neuropsychological and clinical exam with expert adjudication, and depressive symptoms by the Center for Epidemiological Studies Depression Scale (CES‐D). HoloTC and total B12 were measured by radioimmunoassay and radioligand binding assay. After controlling for confounding by age, sex, education, CES‐D, and creatinine, mean 3MSE score was lower in the lowest two holoTC/B12 ratio tertiles vs. the highest tertile (p ≤ 0.02). A significant interaction (p=0.004) between holoTC/B12 ratio and CES‐D score was observed which confined the association between the ratio and 3MSE to subjects with CES‐D ≥ 16. For subjects with CES‐D ≥ 16, the odds ratio for clinical cognitive impairment in the lowest holoTC/B12 ratio tertile was 4.1 (1.4, 12.4) compared with the highest tertile (p=0.01). No associations between cognitive function and holoTC or total B12 alone were observed. HoloTC/B12 ratio may better reflect functional B12 status in the nervous system than either holoTC or total B12 alone.