Are Multiple Sclerosis and Alzheimer’s Disease Related?

Neurological Disorders With Starkly Different Outcomes

Older man sitting in chair and looking off into the distance
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People sometimes confuse multiple sclerosis (MS) and Alzheimer’s disease (AD), two disorders that are characterized by the deterioration of certain neurological functions. Each tends to be progressive in the development of symptoms, and both have the potential to create severe disability in those affected.

But, beyond these effects, both MS and AD have causes, features, and treatments that are entirely unique. As such, they may be considered more like distant cousins, with notable and sometimes striking similarities, rather than direct relations.

Difference in Causes

Multiple sclerosis is considered by many to be an autoimmune disorder in which a person’s own immune response causes damage to the protective coating on nerves (called the myelin sheath). As such, MS is classified as a demyelinating disease in which symptoms are related to the damage incurred by parts of the central nervous system, including the brain, spinal cord, and optic nerves.

While there remains debate as to the exact mechanisms of MS, some scientists believe that the disease may be associated with the Epstein-Barr virus, genetic or environmental factors, or even problems with the metabolization of vitamin D.

The cause of Alzheimer’s remains a bit more obscure. As with MS, factors like genetics, lifestyle, and environment are believed to play a part, although what and how much each contributes is still unclear.

While AD is not considered a demyelinating disease, demyelination is sometimes seen in advance of the appearance of symptoms (most often related to mild memory loss). But unlike MS, the progression of the disease is not related to demyelination. What we see instead is the progressive damage and death to the nerve cells (neurons) in the brain itself.

Differences in Symptoms

Not only does the way in which MS causes nerve damage differ from AD, so, too, do the symptoms. While there is some overlap between the diseases, MS is associated with a wide range of cognitive, motor, and physiological symptoms, while Alzheimer’s primarily manifests with cognitive deterioration.

With MS, pain, tremors, and muscle dysfunction can coexist with urinary, visual, and mood problems. With AD, on the other hand, the disease manifests with the progressive loss of cognition (thoughts, memories, associations) paired with an array of mood and behavioral disorders.

These differences are related to the individual pathways of each disease, including which cells are affected, how they are attacked, and when.

  • With MS, symptoms are largely dependent on where demyelination occurs. The process not only causes nerves to misfire, but it can also severely interrupt communications between nerve cells. It is an abnormal process which can occur at any age from of 20 onward.
  • With AD, symptoms are related to the buildup of proteins, called plaque, between nerve cells in the brain. While this is a considered a normal process as a person ages, it is accelerated and amplified in persons with Alzheimer’s. As such, it tends to be diagnosed more in people over 50 and 60.

Differences in Treatments and Outcomes

Based on the differences in symptoms, it can come as no surprise that the treatment of MS and AD differ, as well.

Treatment of MS is largely centered two things: the reduction of inflammation in joints and tissues with steroids and anti-inflammatory drugs, and the tempering of the immune response with immunosuppressive drugs. Other medications and treatments may be used to control or correct incontinence, sexual dysfunction, vision problems, or mood disorders.

While there is no cure for MS, with proper care and treatment the quality of life can improve significantly, with 40 percent living well into their 70s.

Treatment of AD is far less certain in its outcomes. While there are a number of cognitive-enhancing drugs available today, the response can vary. No treatment is known to cure, reverse, or even significantly slow the progression of the disease. Upon diagnosis, less than three percent of people diagnosed with AD live for more than 14 years.

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Article Sources

  • Burns, A. "Clinical Review: Alzheimer’s Disease." BMJ. 2009; 338:b158.
  • Tsang, B. and Macdonnell, R. "Multiple sclerosis- diagnosis, management, and prognosis". Aus Fam Phys. 2011: 40(12): 948-55.