Serum Vitamin D Concentrations and Cognitive Function in a Population-Based Study among Older Adults in South Germany

Article type: Research Article

Authors: Nagel, Gabriele^{a; *} | Herbolsheimer, Florian^{a; b} | Riepe, Matthias^c | Nikolaus, Thorsten^{d; 1} | Denkinger, Michael D.^d | Peter, Richard^{a; b} | Weinmayr, Gudrun^a | Rothenbacher, Dietrich^a | Koenig, Wolfgang^e | Ludolph, Albert C.^f | von Arnim, Christine A.F.^f | the ActiFE Study group

Affiliations: [a] Institute of Epidemiology and Medical Biometry, Ulm University, Ulm, Germany | [b] Institute of the History, Philosophy and Ethics of Medicine, Ulm University, Ulm, Germany | [c] Department of Psychiatry and Psychotherapy II, Mental Health & Old Age Psychiatry, Günzburg University, Ulm, Germany | [d] Agaplesion Bethesda Clinic, Ulm, Germany | [e] Department of Internal Medicine II Cardiology, University of Ulm Medical Centre, Ulm, Germany | [f] Department of Neurology, Ulm University, Ulm, Germany

Correspondence: [*] Correspondence to: Prof. Dr. med. Gabriele Nagel, MPH, Institute of Epidemiology and Medical Biometry, Ulm University, Helmholtzstr.22, 89081 Ulm, Germany. Tel.: +49 731 50 31073; Fax: +49 731 50 12 31073; E-mail: gabriele.nagel@uni-ulm.de.

Note: [1] Thorsten Nikolaus, the Director of the Agaplesion Bethesda Clinic Ulm, passed away last 26 September 2013. He will be warmly remembered and dearly missed by all. This work is dedicated to him.

Abstract: Our objective was to investigate the associations of vitamin D serum levels with dementia and cognitive function in specific domains in community dwelling older adults. Between 2009 and 2010, we conducted a cross-sectional study in 1,373 individuals (56% men) aged 65+ years in the “Activity and Function in the Elderly in Ulm” (ActiFE) study. Dementia was defined as a Mini-Mental State Examination (MMSE) score ≤ 24. The 25-OHD serum level [ng/mL] was measured by an electrochemilumineszenz immunoassay (ECLIA). Logistic regression models were used to calculate odds ratios (OR)s for cognitive domains (cut-point: 10th percentile) by serum 25-OHD concentrations (both continuously and by cut-point of 20 ng/ml for vitamin D deficiency). Mean age of the study population was 75.6 (SD 6.6) years. We identified 75 participants (43% women) with dementia. 25-OHD concentrations were significantly lower in the participants with dementia compared to persons with a MMSE score >24. We also observed an association of continuous 25-OHD serum concentrations with prevalence of dementia (crude OR 1.05, 95% confidence interval (CI), 1.01–1.08, p-value 0.009) per 1 ng/mL decrease, after adjustment the OR was 1.03, 95% CI, 0.995–1.08 (p-value 0.09). Although vitamin D deficiency was tentatively associated with severity of dementia measured by MMSE (OR 1.35, 95% CI, 0.84–2.19), the association was not statistically significant. However, deficits in specific cognitive domains such as executive functions, wordlist encoding, and visual memory (encoding and recall) were significantly associated with low vitamin D concentration. Our results suggest an association between vitamin D deficiency and cognitive function in specific domains in community dwelling older adults.

Keywords: Cognitive function, dementia, older population, vitamin D

DOI: 10.3233/JAD-143219

Journal: Journal of Alzheimer's Disease, vol. 45, no. 4, pp. 1119-1126, 2015