Vitamin D may play a preventative role in cognitive decline in an elderly Chinese population

Posted on: August 5, 2016   by  Riley Peterson

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The Baby Boomer generation is beginning to reach retirement age, and health care costs increase as more elderly individuals are affected by chronic health conditions and disease. The process of aging puts individuals more at risk for conditions such as arthritis, cardiovascular disease, weakened immune systems, cancer and cognitive diseases such as dementia, Alzheimer’s disease and Parkinson’s. While there are many non-modifiable risk factors associated with some of these conditions, such as genetics, age or gender, there are many modifiable risk factors as well. Lifestyle changes can decrease the risk of disease significantly, which can result in better quality of life, decreased health care costs and more.

Cognitive decline is a condition that some elderly individuals will experience, as a result of both healthy and pathological aging. Individuals may experience a noticeable or measurable decline in cognitive abilities such as thinking, memory and speech. This can have severe effects on the independence of the elderly, which can decrease quality of life significantly. Slowing the process of cognitive decline could have extremely important healthcare implications in an elderly population. Due to the relationship of vitamin D deficiency with both musculoskeletal and neurodegenerative disease, studies have explored the effect of vitamin D on cognitive decline in the elderly. Evidence suggests that vitamin D may have a neuroprotective effect and could be an important in the prevention of cognitive decline

In a recent study, researchers looked at an elderly Chinese population over the span of 2 years to determine if vitamin D had an effect on cognitive decline. The researchers included 1,202 patients over the age of 60 for this study. They measured vitamin D levels and cognitive function at the baseline and end of the study. Cognitive function was measured by the Chinese version of the Mini-Mental State Examination (MMSE), which is a test that measures participants’ orientation, memory, attention, calculation, language, and writ- ten and visual construction. This test is scored by a number system of 0-30, with higher scores indicating better cognition. The participants were split in to 4 quartiles, based on vitamin D levels; the first quartile being the highest vitamin D levels and the fourth quartile having the lowest.

This is what this longitudinal study found:

  • The decline in adjusted mean MMSE score between survey waves was greater in participants in the lowest (−3.05), third (−2.73) and second (−2.37) quartiles of 25(OH)D3 levels than the highest quartiles (−1.44).
  • Participants with lower 25(OH)D3 levels had a higher risk of a decrease of ≥3 MMSE points over the 2-year follow-up compared with those with higher levels. The multivariable ORs (95% CI) of cognitive decline were 2.02 (1.24–3.28), 2.07 (1.26–3.41), and 1.83 (1.10–3.05) for the second, third and lowest quartiles, respectively.
  • The odds of developing cognitive impairment increased with lower 25(OH)D levels; this relationship remained statistically significant after adjustment for age, sex, education, baseline MMSE score, depression, outdoor activities, activities of daily living limitations and other potential confounders.

The researchers concluded:

“In conclusion, our longitudinal study indicates that low 25(OH) D3 levels are associated with subsequent cognitive decline and cognitive impairment.”

While past studies have shown similar results, this was the first to conduct a large, longitudinal, community-based study on the oldest-old of Chinese elderly adults. There were several strengths to this study, such as a prospective design, long follow up time and a large sample population. Additionally, confounding factors were adjusted for. Research supports that vitamin D plays a role in neurological function, and can even reduce the risk of damaging cognitive diseases, such as dementia. In order to prove a causal relationship, though, randomized controlled trials are needed.

Citation

Peterson, R. & Cannell, JJ. Vitamin D may play a preventative role in cognitive decline in an elderly Chinese population. The Vitamin D Council Blog & Newsletter, 2016.

Source

Matchar DB, Chei CL, Yin ZX, Koh V, Chakraborty B, Shi XM, Zeng Y. Vitamin D Levels and the Risk of Cognitive Decline in Chinese Elderly People: the Chinese Longitudinal Healthy Longevity Survey. The Gerontological Society of America, 2016.

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