Международный неврологический журнал 8 (62) 2013

Introduction

One of the most pressing problems in modern neurology is multiple sclerosis (MS) - a common demyelinating neurodegenerative disease of the central nervous system. According to modern notions, MS affects individuals with a genetic predisposition to autoimmune diseases and is influenced by environmental risk factors, which include infection, smoking, geographical factors and vitamin D deficiency. It is considered that hypovitaminosis D is an environmental risk factor for multiple sclerosis, cardiovascular diseases, pneumonia, depression, cataract, breast, prostate and colorectal cancer, leukemia, rheumatoid arthritis, psoriasis, diabetes.

The most important forms of vitamin D are vitamin D₃ (also known as cholecalciferol) and Vitamin D₂ (ergocalciferol). In the liver, cholecalciferol (vitamin D₃) is hydroxylated and converted to 25-hydroxyvitamin D (or 25[OH]D), which is the main vitamin D metabolite. Concentration of 25[OH]D reflects vitamin D level in the body and is the most reliable indicator of the total vitamin D-dependency status. According to the most common classification of vitamin D status, a serum 25-hydroxyvitamin D level below 50 nmol/l is regarded as vitamin D deficiency; vitamin D insufficiency is defined as a 25[OH]D concentration of 510 to 75 nmol/L; a normal level of vitamin D is defined as a 25[OH]D concentration greater than 75 nmol/L.

Having examined data of large prospective epidemiological studies it was noted that multiple sclerosis prevails in regions with insufficient amount of vitamin D, and the number of MS cases declines dramatically closer to the equator, as there is more sun which is the main source of vitamin D. It is that people with low levels of this vitamin in serum/blood are at a significantly higher risk for developing MS. This data may indicate its important role in MS pathogenesis. Vitamin D has immune modulating effects due to its anti-inflammatory immune activity and partially increases the functional capacity of regulatory T cells.

Materials and Methods:

In the period from December 2012 to February 2013, 68 MS patients, residents of Ivano-Frankivsk city and region, including 39 women and 29 men with confirmed MS diagnosis underwent physical, neurological and laboratory examination at the neurological department of Ivano-Frankivsk Regional Clinical Hospital. The average age of MS patients was 37,7 ± 9,7 years, average disease duration was 10,3 ± 6,6 years, and the average severity on the Kurtzke Expanded Disability Status Scale (EDSS) was 4,7 ± 1,3 points. The serum concentration of 25-hydroxyvitamin D (25[OH]D) in MS patients and controls, was measured according to gender, age of patients, duration of disease. To diagnose multiple sclerosis, diagnostic criteria McDonald et al was used (2010). Patients who received hormone therapy, were at the seaside or went to the solarium in the last 3 months prior to physical examination were excluded. This was also the case for the control group. The average age of 10 practically healthy people in the control group was 37,3 ± 8,7 years.

Enzyme-linked immunosorbent assay (ELISA) method (set of IDS OCTEIA) was applied to determine 25-hydroxy vitamin D content in serum, using a special set of reagents manufactured by "IMMUNODIAGNOSTIK SYSTEMS" (Great Britain) and following the manufacturer's instructions. The STAT FAX 303 PLUS (USA) was used to read the results at a wavelength of 450 and 630 nanometers (nm). The statistical analysis of the results of serum 25 [OH]D was performed with the help of the statistics and analytics software package Statistica 7.0, using Student's t-test. Indicators of change were considered credible provided that P<0,05

Results and discussion:

Our studies found a decrease of the vitamin D level in the serum of all examined 68 MS patients, as compared with practically healthy people, (37,3 ± 1,7 nmol/l vurses 69,8 ± 3,3 nmol/l, respectively), which confirms that vitamin D synthesis is disrupted with multiple sclerosis, and these changes are pronounced in both men and women. Note also the factor that members of the control group in Western Ukraine have a low average vitamin D serum concentration compared to normative data (69,8 ± 3,3 nmol/l versus 75.0 nmol/l, respectively) which indicates its deficiency. It was found that vitamin D concentration level in the serum of MS patients doesn’t depend on gender and the duration of the pathological process.

Vitamin D level in the serum of MS patients depends on the age of patients. Thus, there is a statistically significant reduction of vitamin D (p <0,05) among MS patients aged 30-40 years compared to a group of patients aged between 40 and 50 (33,2 ± 2,3 nmol/l versus 42,0 ± 3.5 nmol/l, respectively). It is likely that age 30-40 for our region is an adverse prognostic factor in terms of the development and clinical course of multiple sclerosis. It turned out that vitamin D serum level was significantly higher among women patients with MS under 30 and aged between 40 and 50 than among a selected subgroup of women aged 30-40 years. Thus, it becomes apparent that postmenopausal mechanisms do not cause its reduction in the selected group of MS patients. According to the literature reviews and our research, on average, multiple sclerosis first appears between the age of 30-40. It appears that, vitamin D level decrease is an important etiologic factor in the development of this disease.

Conclusions:

Thus, our studies have shown that vitamin D deficiency in the serum of MS patients is probably one of the etiological factors of the disease. It is confirmed by our findings about its decrease in the serum of MS patients in both men and women of all ages, with different duration of the pathological process. Especially pronounced the changes are among people aged 30-40 years, who can be identified as a risk group multiple sclerosis development in western Ukraine.