Biology: A degenerative affliction

Journal name:
Nature
Volume:
540,
Pages:
S2–S3
Date published:
DOI:
doi:10.1038/540S2a
Published online

Multiple sclerosis often strikes between the ages of 20 and 40, when people are entering the workforce and raising families.

Turning against the self

Multiple sclerosis is an incurable illness in which the body’s own immune system destroys tissues in the central nervous system. T cells and B cells are thought to remove a protective coating called myelin that wraps around nerve fibres in the brain, spinal column and optic nerve. Exposed fibres are degraded, producing symptoms that vary depending on where the damage occurs.

Illustration by Lucy Reading-Ikkanda

A difficult diagnosis

Symptoms differ from person to person, making diagnosis difficult. Common symptoms include vision problems, weakness, instability and loss of bladder control. The proportion of people with some of the most common symptoms are shown below.

Illustration by Lucy Reading-Ikkanda

Types of multiple sclerosis

Relapsing–remitting multiple sclerosis (RRMS) produces attacks followed by periods of remission that can last months or years. It usually gets worse with time. In primary progressive multiple sclerosis (PPMS), symptoms worsen steadily without remission.

Illustration by Lucy Reading-Ikkanda

What causes multiple sclerosis?

The cause is unknown, but it is thought to involve an interplay of genetics and the environment. Genetic susceptibility drives the risk, but the contribution of any specific gene seems to be modest.

Illustration by Lucy Reading-Ikkanda

Global incidence

Multiple sclerosis is most common in northern latitudes, reflecting the likely association with reduced exposure to sunlight and vitamin D deficiency.

Illustration by Lucy Reading-Ikkanda

Disease-modifying therapies

Several drugs have been approved for RRMS, but none for PPMS. Drugs need to be given as soon as possible to slow the pace of neurological damage.

Illustration by Lucy Reading-Ikkanda

Illustration by Lucy Reading-Ikkanda

Sources

Multiple Sclerosis International Federation Atlas of MS 2013 (MSIF, 2013)
MS Brain Health
National Multiple Sclerosis Society
gilenyahcp.com/Novartis Pharmaceuticals

Additional data