The nerve cells in our brain carry messages from the brain to different body parts. These cells are covered with fatty tissues called myelin sheaths that protect them from damage. In multiple sclerosis or MS, our immune system destroys the protective covering and, hence, the nerve cells. This disrupts the communication between our body and brain, causing loss of balance, slurred speech, and other symptoms. This article discusses the types and risk factors for MS.

Types of multiple sclerosis
The National Multiple Sclerosis Society, engaged in research on MS, has categorized the disease into four types based on the symptoms and their duration:

1. Clinically isolated syndrome (CIS)
The first episode of MS is called CIS. The symptoms usually last for at least 24 hours. If an MRI scan does not show any brain lesions, it was probably a one-off episode (or CIS) that will not reoccur. If there are lesions, the person is likely to develop the problem again.

2. Relapsing-remitting MS (RRMS)
If a person keeps experiencing symptoms with periods of remission in between, it is called RRMS. During remission, patients may partially or entirely recover from the symptoms. 85% of MS patients have RRMS, and doctors say it is the most common type.

3. Secondary progressive MS (SPMS)
People with RRMS may progress into SPMS as their condition worsens. Their neurological functions continue to deteriorate and require prompt medical attention.

4. Primary progressive MS (PPMS)
People with PPMS may not see any improvement or remission of any symptoms. The condition continues to deteriorate with time gradually over the years.

Risk factors of multiple sclerosis
Doctors have identified different risk factors of MS based on studies carried out on patients. Some of these are mentioned here:

1. Age
Research shows that people between 20 and 50 are at higher risk of MS. Though it can happen to people of all ages, the highest incidence is recorded in this group.

2. Gender
It is believed that specific hormones make women more susceptible to MS. Research is also underway to understand if any differences in the immune system between women and men could be behind this.

3. Location
Stats have revealed that the prevalence of MS is more common in those living far from the equator. Some health scientists also feel that there could be a relation between UV rays and MS.

4. Ethnicity
White Europeans are at the highest risk of MS. Asians, Hispanics, and African Americans are also susceptible, but the risk is lower. However, these demographics can change over the years.

5. Immune system
MS is an auto-immune disease, and, hence, those with weak or malfunctioning immune systems are at high risk. The immune system treats myelin as an invader and could attack it.

6. Epstein-Barr virus
Epstein-Barr virus, one of the most common human viruses, is known to trigger several health conditions, including MS later in life. There is no vaccine for the virus currently, which makes preventing it a challenge.