Vitamin D and Memory Decline: Two Population-Based Prospective Studies

Article type: Research Article

Authors: Kuźma, Elżbieta^{a; 1} | Soni, Maya^{a; 1} | Littlejohns, Thomas J.^{a; b} | Ranson, Janice M.^a | van Schoor, Natasja M.^c | Deeg, Dorly J.H.^{c; d} | Comijs, Hannie^d | Chaves, Paulo H.M.^e | Kestenbaum, Bryan R.^f | Kuller, Lewis H.^g | Lopez, Oscar L.^h | Becker, James T.^h | Langa, Kenneth M.ⁱ | Henley, William E.^a | Lang, Iain A.^a | Ukoumunne, Obioha C.^a | Llewellyn, David J.^{a; *}

Affiliations: [a] University of Exeter Medical School, Exeter, UK | [b] Clinical Trial Service Unit and Epidemiological Studies Unit, University of Oxford, Oxford, UK | [c] Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands | [d] Department of Psychiatry, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands | [e] Benjamin Leon Center for Geriatric Research and Education, Florida International University, Miami, USA | [f] Kidney Research Institute, Division of Nephrology, University of Washington, Seattle, USA | [g] Department of Epidemiology, University of Pittsburgh, Pittsburgh, USA | [h] Department of Neurology and Psychiatry, University of Pittsburgh, Pittsburgh, USA | [i] Division of General Medicine, Veterans Affairs Ann Arbor Center for Clinical Management Research, Institute for Social Research, and Institute for Healthcare Policy and Innovation, University of Michigan, all in Ann Arbor, USA

Correspondence: [*] Correspondence to: Dr. David J. Llewellyn, University of Exeter Medical School, College House, Heavitree Road, Exeter, EX1 2LU, UK. Tel.: +44 (0) 1392 726018; E-mail: [email protected].

Note: [1] These authors contributed equally to the manuscript

Abstract: Background:Vitamin D deficiency has been linked with dementia risk, cognitive decline, and executive dysfunction. However, the association with memory remains largely unknown. Objective:To investigate whether low serum 25-hydroxyvitamin D (25(OH)D) concentrations are associated with memory decline. Methods:We used data on 1,291 participants from the US Cardiovascular Health Study (CHS) and 915 participants from the Dutch Longitudinal Aging Study Amsterdam (LASA) who were dementia-free at baseline, had valid vitamin D measurements, and follow-up memory assessments. The Benton Visual Retention Test (in the CHS) and Rey’s Auditory Verbal Learning Test (in the LASA) were used to assess visual and verbal memory, respectively. Results:In the CHS, those moderately and severely deficient in serum 25(OH)D changed -0.03 SD (95% CI: –0.06 to 0.01) and –0.10 SD (95% CI: –0.19 to –0.02) per year respectively in visual memory compared to those sufficient (p = 0.02). In the LASA, moderate and severe deficiency in serum 25(OH)D was associated with a mean change of 0.01 SD (95% CI: –0.01 to 0.02) and –0.01 SD (95% CI: –0.04 to 0.02) per year respectively in verbal memory compared to sufficiency (p = 0.34). Conclusions:Our findings suggest an association between severe vitamin D deficiency and visual memory decline but no association with verbal memory decline. They warrant further investigation in prospective studies assessing different memory subtypes.

Keywords: Cognition, memory, prospective studies, vitamin D

DOI: 10.3233/JAD-150811

Journal: Journal of Alzheimer's Disease, vol. 50, no. 4, pp. 1099-1108, 2016