Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system. Approximately 400,000 people in the United States are affected by MS.
Patients with MS experience a wide variety of symptoms, such as vertigo, difficulty walking, bladder problems and trouble thinking clearly. While the cause remains unknown, the disease is thought to be triggered in genetically susceptible individuals by a combination of environmental factors, including smoking and vitamin D deficiency.
Research has shown that low vitamin D levels are linked to an increased risk of MS and increased disease activity in MS patients. An animal study showed that vitamin D supplementation prevents the onset of the disease in MS animal models. Furthermore, a randomized controlled trial found that vitamin D supplementation improved the quality of life among patients with MS.
A recent clinical trial aimed to evaluate cognitive performance in MS patients with vitamin D deficient levels (< 25 ng/ml) compared to patients with sufficient levels (> 35 ng/ml). More importantly, the researchers evaluated the change in cognitive performance after three months of vitamin D3 replacement.
The researchers enrolled 88 MS patients over the age of 18 years old and treated with interferon beta, a standard treatment for MS. A total of 41 patients were considered vitamin D deficient (<25 ng/ml) at the beginning of the study, and thus, received 10,000 IU of vitamin D3 daily for three months. The 47 vitamin D sufficient (>35 ng/ml) followed their typical care and supplementation regimen. The researchers assessed cognitive performance and vitamin D status before the patients supplemented with vitamin D and after three months of supplementation.
Three cognitive performance tests were used to assess various cognitive fields, including verbal memory, learning, attention, information processing speed and visuospatial perception.
The researchers assessed cognitive performance and vitamin D status before the patients supplemented with vitamin D and after three months of supplementation.
The following cognitive performance tests were performed:
- Stroop test: The test assesses cognitive processing by observing how fast individuals can read words and name colors.
- Brief Visuospatial Memory test (BVMT): As the name suggests, this test measures memory and visuospatial skills.
- Montreal Cognitive Assessment (MoCA): MoCA screens for mild cognitive dysfunction by assessing attention and concentration, executive functions, memory and other cognitive domains.
- The Symbol Digit Modalities Test (SDMT): This test provides a quick screening tool for brain dysfunction in children and adults.
After three months of vitamin D supplementation, the average vitamin D levels increased from 15.8 ng/ml to 49.0 ng/ml in the vitamin D deficient group (p < 0.001). Average vitamin D levels remained similar, slightly increasing from 59.6 ng/ml at baseline to 64.2 ng/ml in the sufficient group that received usual care.
BVMT and MoCA scores significantly improved after three months among those who received vitamin D supplementation (p < 0.05). However, SDMT scores did not improve. Both groups showed improvement on the Stroop test, but the improvement was not statistically significant (p = 0.56).
The researchers concluded,
“In summary, our study suggests a positive effect of vitamin D3 supplementation on cognitive function in MS.”
They went on to state,
“Improving cognition early in the course of the disease with a simple intervention such as vitamin D3 supplementation could make a significant difference in the patient’s quality of life.”
The study design contained both limitations and strengths. Since the study included an intervention, the researchers successfully proved that vitamin D supplementation causes an improvement in cognition. However, the study did not possess a control group, meaning the placebo effect may be involved with the observed improvements. Another limitation of the study was its relatively short time frame. A longer duration may have led to greater improvements. Lastly, only about half of the patients used a lifestyle diary as instructed. The patients’ poor response rate to lifestyle diary limited the researchers’ ability to control for other sources of vitamin D as possible confounders. It also raises question of compliance.
The researchers announced that a improved study will be conducted in the near future.
“Thus, exploring the longitudinal effect (at least 1 year) of vitamin D3 replacement on cognitive performance in a larger sample of MS subjects with 25 (OH)D deficiency is being planned; while placing more emphasis on additional memory components; such as, verbal memory.”
However, the researchers will probably have to treat the control group with at least 600 IU/day in order to get the study past their Ethics Commitee.
Tovey, A. & Cannell, JJ. Vitamin D improves cognition in MS patients, according to recent study. The Vitamin D Council Blog & Newsletter, April 11, 2017.