Findings from a recent study on low levels of vitamin D and dementia in the elderly may help doctors identify people who are at higher risk.
Memory Loss in Seniors and Low Levels of Vitamin D
Researchers from Britain, Italy and the United States studied more than 850 people over the age of 65 over a six-year period, according to a report in the July 12 2010 issue of the Archives of Internal Medicine.
David J. Llewellyn, Ph.D., of University of Exeter, England, and colleagues analyzed the blood levels of vitamin D in the test subjects. Participants completed interviews and medical examinations and provided blood samples. At the start of the study and after three and six years, scientists repeated three tests to measure cognitive function, one to determine overall cognition, one that focused on attention, and one that assessed executive function, a person's ability to plan, organize and prioritize.
"The results of these observational studies have prompted calls for widespread treatment of individuals with low levels of vitamin D and the establishment of public health programs aimed at raising the population levels of vitamin D to 'healthy' values," the authors of the study write.
Cognition and Brain Functioning Assisted With Vitamin D
Scientists believe vitamin D may help prevent brain tissue degeneration by contributing to the formation of nervous tissue, maintaining levels of calcium in the body, or clearing of beta-amyloid, the substance that forms the brain plaques and tangles associated with Alzheimer's disease.
Researchers found that test participants who were severely deficient in vitamin D (blood levels of 25-hydroxyvitamin D less than 25 nanomoles per liter) were 60 percent more likely to have severe cognitive decline over the six-year test period and were 31 percent more likely to show declines on executive functions than participants who had sufficient vitamin D levels.
While researchers saw a link between low D levels and a decline in overall cognition and executive functioning (planning, organizing, prioritizing), they did not find a significant association between low vitamin D levels and attention.
Vitamin D Deficiency Linked to Numerous Health Conditions
Vitamin D in its active form (1,25-dihydroxyvitamin D) binds to receptors in the body's cells. Despite the name, vitamin D is actually a secosteroid hormone that targets over 2000 genes.
The "sunshine vitamin" is increasingly making health news because scientists believe D may have a positive effect on bone health, immunity, cancer prevention and inflammation, and now according to the recent finding, in reducing the risk of dementia.
Taken orally, vitamin D is absorbed with fat through the intestinal walls and is stored in the fat cells of the liver, skin, brain and bones in amounts sufficient for many months. While not readily available in foods, vitamin D is made in large quantities when sunlight strikes bare skin, which is why a deficiency is more common in the winter.
Dr. Cannell, Executive Director of the Vitamin D Council, suggests vitamin D deficiency is actually a syndrome as indicated by “symptoms or signs typical of a disease, disturbance, condition, or lesion, a set of concurrent things and a derangement of function.”
Vitamin D Deficiency Syndrome (VDDS) “is the aggregate of symptoms and signs associated with the morbid process of vitamin D deficiency, and constitute together the picture of the disease,” writes Cannell on the Council's website. Some of the diseases associated with low D may include:
- osteoporosis
- heart disease
- hypertension
- autoimmune diseases
- certain cancers
- depression
- chronic fatigue
- chronic pain
Cannell and other researchers are not suggesting that low D causes these illnesses or that elevating D to optimal levels will cure an illness. They suggest certain disease states are associated with low levels of D.
Vitamin D Deficiency Common Among Seniors, Overweight, Dark-skinned, Sun-avoiders and Sick
The production of vitamin D in the body can be halted by anything that blocks ultra violet light including skin pigment, smog, fog, sunscreen, windows and hats. A number of other factors may contribute to low D levels, including malabsorption, a condition common in people with inflammatory bowel diseases.
According to the Council’s website individuals may need more vitamin D if they are:
- older
- heavier
- Northerners (less year round sun exposure)
- dark-skinned
- winter people (less sun exposure)
- sunblock lovers
- sun-avoiders
- sick
The Department of Public Health at Weill Cornell Medical College cites that one in seven American adolescents are vitamin D deficient and that:
- More than half of African-American teens are vitamin D deficient.
- Girls had more than twice the risk of deficiency compared to boys.
- Overweight teens had nearly double the risk of their normal-weight counterparts.
- Only 4 percent of men and 1 percent of women over the age of 51 meet vitamin D recommendations from food.
Several factors increase a person's risk for dementia such as age, gender (some types of dementia are more common in women, while others are more common in men), Alzheimer's disease, Lewy body dementia, high blood pressure, stroke, menopause, family history and genes, Down syndrome, toxins, head injury, high cholesterol, diabetes, smoking, obesity, atrial fibrillation. Recent findings suggest that individuals with low vitamin D levels may also be at increased risk for dementia.
Resources:
David J. Llewellyn; Iain A. Lang; Kenneth M. Langa; Graciela Muniz-Terrera; Caroline L. Phillips; Antonio Cherubini; Luigi Ferrucci; David Melzer. “Vitamin D and Risk of Cognitive Decline in Elderly Persons,” Archives of Internal Medicine 2010.
Andrew Grey; Mark Bolland. “Vitamin D: A Place in the Sun?” Archives of Internal Medicine, 2010. “1 in 7 U.S. Teens Is Vitamin D Deficient.” March 11, 2009. Public Health Department of Weill Cornell Medical College.
Cannell, John Jacob, MD, "Vitamin D Deficiency Syndrome,"The Vitamin D Council, December 2003, (Updated January 2010).
Laura Owens - Laura Owens has a B.S. in Psychology from Rollins College & U of FL. She is a freelance writer with expertise in motivation & wellness.
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