Cognitive Changes

MS may affect cognitive function for several reasons, but the most pervasive is thought to be damage to the nerve cells (“axonal injury”). Stress, anxiety, fatigue, depression, and medication side effects (the indirect effects of the disease process) can also play a role in cognitive dysfunction.

While people who have had MS for a long period of time seem to be more prone to these problems, cognitive dysfunction can be seen early in the disease and have an impact at home or work. Even mild symptoms can be troubling, especially if they interfere with the important tasks of daily living. In fact, people with MS are more likely to leave the work force because of cognitive symptoms and fatigue.

It's important to have any cognitive problems evaluated early on so you can develop a treatment plan with members of your health care team. The following problems seem to be the most common.

Memory Loss

Memory loss is more likely than other problems to be overlooked and misunderstood. But memory problems are the most common type of cognitive dysfunction in MS and can occur at any time during the disease. Recent memory is most often affected by MS. Recent memory refers to newly learned information, such as a person's name or a telephone number. It also includes things you are trying to remember for the future, such as stopping at the store on your way home from work.


It is important to note that memory loss does not necessarily indicate diminished intelligence or the ability to learn. The brain may simply need more time to recall information from memory or to learn new information. Taking more time to think and having a supportive atmosphere can help solve these challenges.

Forgetting names, losing or misplacing things, and forgetting what you were just doing are all symptoms of memory loss, although it's safe to say everyone experiences these moments from time to time. (Later this chapter will discuss ways to evaluate your cognitive difficulties and learn when to seek help.) Other common cognitive problems may include the following:

  • Attention and concentration. For many people with MS, maintaining concentration and attention for single tasks is easier than having to focus on several things at once or having to multitask. Folks who have problems with concentration may find it easier to work on just one thing at a time in a quiet environment.

  • Visual spatial skills. People with MS may have problems perceiving or recognizing objects or orienting themselves. This can interfere with activities such as reading maps or looking at diagrams or charts. It can also make driving difficult.

  • Problem solving. When confronted with a problem, people with cognitive dysfunction may have difficulty coming up with a solution, or they choose the same solution over and over instead of generating a new one.

  • Language. The types of language problems most often seen in MS are related to fluency — finding the right words to use when speaking, or using the wrong word.

  • Processing speed. When processing speed is impaired, a person may have difficulty processing incoming information; they experience a “slowing down” in their brain or a lag in their thoughts.

  • Cognitive fatigue. Studies show that people with MS can get fatigued when doing challenging work over a long period of time. Some people call it “brain fog.” A timeout or a quick break is often helpful in resolving this type of fatigue.

  • Planning and organizing abilities. People with cognitive difficulties may find it hard to plan or organize.

Research has shown that there are some general tendencies when it comes to cognitive difficulties. Firstly, there is little or no relationship between duration of MS and the severity of cognitive changes. In other words, just because you've had MS for twenty years doesn't mean that you are more likely to experience cognitive symptoms.

People with a progressive form of the disease are at a slightly greater risk of having cognitive problems. Although it's not inevitable, cognitive changes can progress like other symptoms. They can also improve or stay the same.


Recent studies have shown that about half of all people with MS show no evidence of cognitive dysfunction. About 40 percent have mild dysfunction while 5 to 10 percent have moderate to severe impairments. This means that nine out of ten people with MS are free of severe cognitive difficulties.

Finding Help

If you suspect you might be experiencing cognitive changes, the first thing to do is get in to see your doctor and discuss your concerns. Since so many of these symptoms happen to everyone on occasion, how do you decide if you need help?

The general rule of thumb is to seek an expert opinion when anything that's going on with your life causes you concern. You might say “Geez, I notice I've been doing that a lot lately,” or “My bad memory seems to be interfering with my work.” If the problem is more subtle, here are some clues that you may need an evaluation:

  • You can't explain why things seem more complicated lately at work or at home.

  • You notice your memory is failing you several times a day, or more than is normal for you.

  • Others have noticed a change in your performance at work or at home and you've eliminated the usual suspects, such as stress or depression.

  • You just feel different, perhaps foggy or mentally drained.

The first signs of cognitive dysfunction may be subtle. Often, the family becomes aware of the problem first, noticing changes in behavior or personal habits. Discussing the problem is important, as coping and management strategies can help reduce stress and limit the impact of the symptom. Education, understanding, and acknowledgement play important roles in the social support system on the part of the person with MS.

Three different types of health professionals are able to evaluate cognitive problems: neuropsychologists, speech/language pathologists, or occupational therapists. Your best bet is to ask your neurologist for a recommendation. Whom you seek help from may largely depend on what types of professionals are available in your area. Each uses a different method to assess your difficulties but all three can be effective in diagnosing and measuring cognitive dysfunction.

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