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Vitamin D levels may affect brain health in Parkinson's disease: brain tissue; particularly in the hippocampus, contains vitamin D receptors.

Vitamin D may be best known as a building block for healthy bones. But this important nutrient is also vital for maintaining muscle mass, supporting your immune system and for healthy functioning of the entire body. Recently, researchers at Oregon Health and Sciences University reported that higher levels of vitamin D are also associated with greater cognitive ability and improved mood in people with Parkinson's disease (PD). PD is one of several motor system disorders that result from a diminished supply of dopamine in the brain. The study was published in the Journal of Parkinsons Disease.

"About 30 percent of persons with PD suffer from cognitive impairment and dementia, and dementia is associated with nursing home placement and shortened life expectancy," says study author Amie L. Peterson, MD. "We know mild cognitive impairment may predict the future development of dementia. Intervening in the development of dementia has the potential to improve morbidity and mortality in persons with PD."

VITAMIN D AND DEMENTIA. Of the 286 people in the study, 61 were considered to be demented, and 225 did not have dementia. Researchers found that average vitamin D levels tended to be higher in the non-demented study participants. Those without dementia and higher vitamin D levels demonstrated greater fluency in naming vegetables and animals. They also performed better on tests of verbal learning.

"The fact that the relationship between vitamin D concentration and cognitive performance seemed more robust in the non-demented subset suggests that earlier intervention before dementia is present may be more effective," Dr. Peterson suggests.

Low levels of vitamin D were also strongly associated with depression, especially for participants without dementia.


why vitamin D may help improve brain function and mood isn't entirely clear. Brain tissue, particularly in the hippocampus, contains vitamin D receptors, which suggests the need for a healthy supply of vitamin D. The hippocampus is the part of the brain that plays a key role in memory and learning.

But researchers admit the study was not designed to prove a cause-and-effect relationship between vitamin D and brain health. Several questions remain. For example, does vitamin D play a direct role in mood and cognitive function, or is it that people with advanced PD and dementia get less sunlight--a key source of vitamin D in the body?


In addition, the study did not consider if the patients took vitamin D supplements. Researchers suggest that the next phase of the study could focus on whether actively raising a person's vitamin D levels to a healthier range can reverse mood and cognition problems or at least delay the onset of dementia and other complications.

HOW MUCH IS ENOUGH? Just as low levels of vitamin D can negatively affect your health, so too can very high levels. The average diet and sun exposure for most people may provide enough vitamin D. But if you're at high risk for osteoporosis or you live in a region that gets little sunlight, your doctor may suggest vitamin D supplements. However, even here, opinions vary on safe and effective amounts of vitamin D supplementation.

The National Institutes of Health suggest that 1,000 IU to 2,000 IU of vitamin D supplements may be appropriate for most older adults. A simple blood test for serum 25-hydroxyvitamin D will determine if you're getting enough vitamin D. Though there is some debate about ideal levels, the NIH says that 50 nmol/L of serum 25-hydroxyvitamin D is ideal for most people.

If you have concerns about your vitamin D levels, and whether you're consuming too much or too little, talk with your doctor and make sure your next blood work includes a test for serum 25-hydroxyvitamin D.



SOPHIA WANG, MD, Staff Psychiatrist-Durham Veterans Affairs Medical Center; Assistant Professor of Psychiatry and Behavioral Sciences, Department of Psychiatry-Division of Psychiatry/Geriatric Behavioral Health, Duke

Promising evidence of Vitamin D's Importance

"This study provides promising preliminary evidence that vitamin D plays an important role in cognitive function. These results are exciting for two reasons: First, the drugs currently used for cognitive impairment in Parkinson's disease were originally designed for Alzheimer's disease. This study supports the importance of looking at treatments which are specific to cognitive impairment in Parkinson's disease. Second, given recent data that vitamin E supplementation prevents functional decline in Alzheimer's disease, this study also supports the need to better understand the role of vitamins in dementia. If future clinical trials can show that vitamin supplements slow the progression of cognitive decline in Parkinson's disease by even only one or two years, this still will provide significant relief for patients and their caregivers."
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Title Annotation:MIND & MEMORY
Publication:Duke Medicine Health News
Date:Apr 1, 2014
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