The Effect of Vitamin D Supplementation on Neurocognitive Function in Older Subjects

Background: Ageing is associated with an increased risk of cognitive decline. Vitamin D plays an important role in many of the symptoms and conditions related to advanced age, including impaired balance, falls and osteoporosis. Vitamin D also has a physiological effect on the function of the central nervous system, and studies have suggested a relationship between this vitamin and changes in cognitive function of older people. The investigators propose a pilot study to evaluate the effect of vitamin D supplementation on the neurocognitive function of older people.

Methods: A total of 30 subjects of both genders older than 65 years with levels of 25-OH Vitamin D lower than 30 ng/ml on routine laboratory screening will be included in the study. Exclusion criteria will include any unstable medical condition as determined by the treating physician, a diagnosis of dementia, the use of supplements containing vitamin D in any dose, significant visual or hearing impairment not corrected by spectacles or hearing aids, and a level of literacy that limits the performance of computerized neurocognitive testing. Following provision of written informed consent for inclusion in the study, subjects will answer a questionnaire providing demographic details, undergo cognitive screening by use of the MoCA test, and computerized cognitive assessment using the Neurotrax battery. All subjects will undergo repeat testing for level of 25-OH Vitamin D, and where below-normal levels are confirmed patients will receive a supplemental monthly oral dose of 60000 units Vitamin D administered by a nurse for a period of 3 months. Levels of serum calcium will be repeated monthly (end of month 1, 2, 3). At 3 months subjects will undergo repeat testing for level of 25-OH Vitamin D, and repeat computerized cognitive assessment using the Neurotrax battery.