In past decades, cognitive impairment (CI) was underestimated in multiple sclerosis (MS) patients and thought to appear only in primary progressive (PP) and secondary progressive (SP) disease stages. Presently, it is well established that CI affects a large proportion of MS patients from onset to all disease stages. In a recent study, researchers have found that low vitamin D levels worsen both cognition and early disability in newly diagnosed MS patients. The study findings were published in the journal Brain Sciences on November 17, 2021.
Few studies explored the possible correlation between CI and vitamin D in the MS population. However, studies on vitamin D supplementation so far have not included cognitive evaluation, Although vitamin D and cognitive impairment in other neurodegenerative diseases have already been linked. Therefore, Dr Eleonora Virgilio and her team conducted a study to explore the possible correlation between vitamin D and cognition, particularly information processing speed (IPS), early in the disease, precisely at MS diagnosis, using the Symbol Digit Modalities Test (SDMT).
In this retrospective study, the researchers included a total of 81 newly diagnosed MS patients who displayed both serum vitamin D sampling and SDMT assessment at diagnosis, at least after 1 year of follow-up. They adjusted raw scores for age, gender, and educational level. They evaluated early disability with MS severity score (MSSS) and age-related MSSS (ARMSS).
Key findings of the study:
Among 81 patients, the researchers observed hypervitaminosis D (19.71 ± 8.76 ng/mL) in 17 patients (86.58%) and noted 18 patients (21.95%) had CI.
They found that patients with CI showed severe hypovitaminosis D.
They observed that no patients with sufficient vitamin D levels had CI.
They also found a positive correlation between vitamin D levels at diagnosis and
◊ SDMT raw and z-score that persisted after correction for sunlight exposure and MRI baseline characteristics, and
◊ EDSS, MSSS, and ARMSS after a mean 2-year follow-up.
The authors concluded, "Our data support the hypothesis that vitamin D is involved in cognition in MS. This vitamin reduces CNS inflammation and promotes neuronal survival, suggesting that inadequate vitamin D levels could affect neuroaxonal integrity and the immune system, contributing to short-term effects on cellular homeostasis and long-term effects on neuronal loss. These processes in individuals with MS, consequently, may reflect slowed IPS upon diagnosis, which may influence their quality of life."
For further information:
Virgilio E, Vecchio D, Crespi I, Barbero P, Caloni B, Naldi P, Cantello R, Dianzani U, Comi C. Serum Vitamin D as a Marker of Impaired Information Processing Speed and Early Disability in Multiple Sclerosis Patients. Brain Sciences. 2021; 11(11):1521. https://doi.org/10.3390/brainsci11111521