Multiple sclerosis: forms and causes

Forms of multiple sclerosis

  1. Relapsing-remitting MS (RRMS)
    It is the most common form and is characterized by attacks or flare-ups with deterioration of neurological functions.
    These flare-ups (relapses) have followed periods of partial or complete recovery (remission or asymptomatic disease) in which symptoms partially or completely improve and no further progression of the disease is evident (Weiner – 2008).
    At this stage, MS does not lead to constant impairment.
  2. Secondary-progressive MS
    This form follows the relapsing-remitting type.
    Most individuals experience constant progression (even if it is not necessarily faster) with or without relapses.
  3. Primary progressive MS
    It is characterized by a constant neurological deterioration from the onset of the disease.
    The rate of progression may vary.
  4. Progressive-recurrent MS
    This form is the least common and is characterized by a constant progression of the disease from the very beginning and several exacerbations during life.
    People with this form of MS may not always experience recovery after each flare-up; the disease progresses without remission.

This disease should not be confused with amyotrophic lateral sclerosis (ALS), which leads to paralysis of limbs, muscles and impairment of swallowing and speech functions.
ALS also causes fasciculations, while MS usually does not.

Causes of multiple sclerosis

The cause of multiple sclerosis is unknown. Experts believe that it is an autoimmune disease: The immune system attacks the body tissues. In MS, the antibodies destroy the myelin. Myelin is a fatty substance that encloses and protects the nerve fibers in the brain and spinal cord.
Myelin can be compared to the plastic layer that insulates electrical wires. The myelin damage in the brain and spinal cord slows or blocks nerve signals.

Risk factors
These factors can increase the risk of developing multiple sclerosis:

  • Age: MS can occur at any age, but is most common between 20 and 40 years of age.
  • Gender: Women are twice as likely to be affected by MS as men.
  • Heredity: If a parent or sibling has MS, the risk of developing MS is greater.
  • Infections: Many viruses are related to MS. The pathogens are: Epstein-Barr virus, i.e. the virus that causes mononucleosis.
  • Race: Fair-skinned people, especially Caucasians, are at higher risk of developing MS.
  • Climate: Multiple sclerosis is much more common in countries with temperate climates, such as the United States (including southern Canada), New Zealand, Australia and Europe.
  • Autoimmune diseases: People with an autoimmune disease carry a higher risk of developing MS. Thyroid disease, type 1 diabetes or inflammatory bowel disease (Crohn’s disease and ulcerative colitis) can also increase the risk of developing MS (Kosmidou et al. – 2017).
  • Smokers: Smokers are more likely to develop MS than non-smokers.

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