Vitamin D and neuropsychological assessment of cognitive functions: a study of their relationships in a sample of 244 patients attending a memory clinic

Abstract

There is evidence of a role of vitamin D in cognitive functioning, but little is known about the type of functions involved. To describe vitamin D status in a population of old patients with memory complaints and its relationships with cognitive performance and white matter lesions. A retrospective single-centre observational study from the medical records of 244 patients who had a measurement of serum 25OHD together with a battery of neuropsychological tests during a complete geriatric and memory assessment in a day care hospital. The results of the 10 neuropsychological tests considered in this study were analysed as binary variables, opposing patients with results within the highest two tertiles to patients with the worse results or unable to perform the test. Mean age of people included was 80.2 ± 8.1 years and 64% of patients were women. Severe deficiency in vitamin D (25OHD <10 ng/mL) was found in 34 patients (13.9%) and moderate deficiency (10 ≤ 25OHD < 30 ng/mL) in 148 (60.7%). Compared to subjects with sufficient concentrations in vitamin D, patients with severe deficiency performed significantly worse on a global test, the Mini mental state examination, and two tests of verbal memory, the 5 words and the 16-item free and cued recall, independently from age, gender, education, body mass index and autonomy (OR = 2.85 [1.04-7.85], 4.31 [1.42-13.07], and 3.04 [1.01-9.19] respectively). Levels of vitamin D did not differ according to the extent of white matter lesions, visualized semi-quantitatively on magnetic resonance imaging of 115 subjects. This study confirms the high prevalence of vitamin D deficiency in elderly population and suggests a link between vitamin D deficiency and memory.