Dement Geriatr Cogn Disord 2014;38:254–263 DOI: 10.1159/000362870 Accepted: April 11, 2014 Published online: June 25, 2014

© 2014 S. Karger AG, Basel 1420–8008/14/0384–0254$39.50/0 www.karger.com/dem

Original Research Article

Serum 25-Hydroxyvitamin D and Cognitive Decline: A Longitudinal Study among Non-Demented Older Adults Laura Perna a

Ute Mons a

Matthias Kliegel b

Hermann Brenner a

a Division

of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg, Germany; b Department of Psychology, University of Geneva, Geneva, Switzerland

Key Words Cognitive Telephone Screening Instrument · Cognitive impairment · Elders · Vitamin D Abstract Background/Aims: Very few studies have investigated the longitudinal association between serum levels of 25-hydroxyvitamin D [25(OH)D] and cognitive impairment not due to dementia. This longitudinal study analysed 25(OH)D and the risk of cognitive decline among nondemented older adults. Methods: A subsample of the ESTHER cohort study, aged ≥70 years, was assessed with the Cognitive Telephone Screening Instrument (COGTEL) and underwent 25(OH)D measurements standardized with a reference method (n = 1,302). After an average follow-up of 4.6 years, 527 participants had repeated COGTEL testing and were eligible for analysis. Linear regression models were used to assess longitudinal associations between 25(OH)D levels and cognitive function. Possible practice effects of repeated cognitive testing were addressed with the reliable change index. Results: A trend of a more pronounced cognitive decline with lower vitamin D levels was observed among both women and men, with a statistically significant difference in COGTEL scores in the lowest vitamin D quintile of the total sample. Conclusions: This study indicates that low levels of vitamin D might be associated with cognitive decline among non-demented elderly individuals and highlights the need for further large-scale prospective studies to clarify the potential role of vitamin D in cognitive © 2014 S. Karger AG, Basel function at an old age.

Laura Perna Division of Clinical Epidemiology and Aging Research German Cancer Research Center (DKFZ), INF 581/TP4 DE–69120 Heidelberg (Germany) E-Mail l.perna @ dkfz-heidelberg.de

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Dement Geriatr Cogn Disord 2014;38:254–263 DOI: 10.1159/000362870

© 2014 S. Karger AG, Basel www.karger.com/dem

Perna et al.: Serum 25-Hydroxyvitamin D and Cognitive Decline: A Longitudinal Study among Non-Demented Older Adults

Introduction

Vitamin D, a secosteroid hormone, is mostly produced in the skin after sun exposure and, in smaller amounts, provided by dietary supply. Serum levels of 25-hydroxyvitamin D [25(OH)D] are considered the best biomarker of vitamin D status. They have been found to decrease with age [1], and low levels have been associated with increased mortality [2] and an increased risk of a variety of chronic diseases among older adults [3]. In vitro studies showed that vitamin D increased the synthesis of neurotrophins, and studies in humans seemed to confirm that vitamin D might be implicated in neurocognitive function [4, 5]. Low levels of 25(OH)D have been associated with cognitive impairment among women in several cross-sectional studies [6, 7], and among men in a large study including 3,133 noninstitutionalized males [8]. Among women and men receiving home services, low levels of 25(OH)D were associated with dementia and cerebrovascular pathology [9], and among older patients at a memory clinic, hypovitaminosis D was associated with executive dysfunction [10]. Meta-analyses and systematic reviews of epidemiological studies also seem to suggest that low serum concentrations of 25(OH)D are associated with cognitive impairment and an increased risk of dementia [11–14]. Very few longitudinal studies assessed the association between lower 25(OH)D levels and cognitive decline among elderly persons, and they delivered conflicting results. Two studies found an approximately 60% increased risk of cognitive decline among participants aged ≥65 years with severely deficient 25(OH)D levels (

Serum 25-hydroxyvitamin D and cognitive decline: a longitudinal study among non-demented older adults.

Very few studies have investigated the longitudinal association between serum levels of 25-hydroxyvitamin D [25(OH)D] and cognitive impairment not due...
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