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Research and Projects

Vitamin D and Cognitive Health: the DCog Project

Theme: CLAHRC - Mental Health & Dementia
Status: Complete

Read a BITE sized summary of this project.


The National Dementia Strategy estimates that there are over 750,000 people in the UK with dementia and with an aging population, numbers are likely to double in the next thirty years.  Dementia is characterised by loss of cognitive functions such as memory and problem solving. It exceeds what would be expected from ‘normal’ ageing and affects work and everyday life. People with mild/moderate cognitive impairment (MCI) have deficits in one or more cognitive domains, such as memory, but these have not progressed to the degree that daily activities become difficult.

Vitamin D deficiency is common in older adults and mounting evidence suggests that vitamin D may help to protect against dementia. Vitamin D stimulates the immune system to remove harmful substances from the brain, may protect against Alzheimer’s disease, and may reduce the risk of stroke.

Project aims

The aim of this project was to improve outcomes for people with dementia or cognitive decline, and to investigate factors which might be effective in midlife to lower the risk of dementia in later years. Contributing to this by:

  • Working to determine the impact of Vitamin D on cognitive decline by reviewing literature
  • Engaging service users in this process
  • Using large pre-existing datasets to investigate the effects of vitamin D levels on dementia risk over time
  • Applying for funding for a large-scale investigation into the effectiveness and cost-effectiveness of Vitamin D in preventing cognitive decline.

Related news stories


1. Soni M, Kos K, Lang IA, Jones K, Melzer D, Llewellyn DJ. Vitamin D and cognitive function. Scand J Clin Lab Invest Suppl 2012;243:79-82.
2. Llewellyn DJ, Lang IA, Langa KM, Muniz-Terrera G, Phillips CL, Cherubini A, et al. Vitamin D and risk of cognitive decline in elderly persons. Arch Intern Med 2010;170(13):1135-41.
3. Balion C, Griffith LE, Strifler L, Henderson M, Patterson C, Heckman G, et al. Vitamin D, cognition, and dementia: A systematic review and meta-analysis. Neurology 2012;79(13):1397-405.

Others Involved

Dr David Llewellyn, Dr Andy Gibson


Dr Maya Soni
Peninsula Clinical Trials Unit
Representatives from the Patient/Public Involvement Group