Cognitive impairment linked to low vitamin D levels

In an article scheduled for publication in the Journal of Geriatric Psychology and Neurology, researchers from the Peninsula Medical School, the University of Cambridge, and the University of Michigan report an association between low levels of vitamin D and an increased risk of cognitive impairment in older men and women. Cognitive impairment has been shown to enhance the risk of developing dementia, a major cause of disability among older individuals.

The current study included 708 men and 1,058 women aged 65 and older who participated in the Health Survey for England 2000. Neurocognitive testing revealed cognitive impairment in 212 subjects. The risk of impairment was found to increase with declining levels of serum 25-hydroxyvitamin D. Participants whose vitamin D levels were among the lowest 25 percent of participants at 8-30 nanomoles per liter experienced an adjusted risk of cognitive impairment that was 2.28 times greater than that of men and women whose vitamin D levels were in the top quarter at 66 to 170 nanomoles per liter.

“We provide new evidence to suggest that serum 25-hydroxyvitamin D is related to cognitive impairment in the elderly population and a potential diagnostic aid for screening or differential diagnosis,” the authors write. “This is important because serum 25-hydroxyvitamin D may play an important role in the expression of neurotrophic factors, the stimulation of adult neurogenesis, calcium homeostasis, and detoxification. Furthermore, the association between serum 25-hydroxyvitamin D levels and cognitive impairment underlines the importance of micronutrients in the elderly.”

"This is the first large-scale study to identify a relationship between vitamin D and cognitive impairment in later life,” noted study coauthor Iain A. Lang, PhD, of Peninsula Medical School in Exeter, England. “Dementia is a growing problem for health services everywhere, and people who have cognitive impairment are at higher risk of going on to develop dementia. That means identifying ways in which we can reduce levels of dementia is a key challenge for health services."

"For those of us who live in countries where there are dark winters without much sunlight, like the UK, getting enough Vitamin D can be a real problem – particularly for older people, who absorb less vitamin D from sunlight.,” Dr Lang observed. “One way to address this might be to provide older adults with vitamin D supplements. This has been proposed in the past as a way of improving bone health in older people, but our results suggest it might also have other benefits. We need to investigate whether vitamin D supplementation is a cost-effective and low-risk way of reducing older people's risks of developing cognitive impairment and dementia."