Cognitive Function
SOURCE: www.NationalMSSociety.org
Cognition refers to a range of high-level brain functions, including the ability to learn and remember information: organize, plan, and problem-solve; focus, maintain, and shift attention as necessary; understand and use language; accurately perceive the environment, and perform calculations. Cognitive changes are common in people with MS—approximately 50% of people with MS will develop problems with cognition.
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A person may experience difficulties in only one or two areas of cognitive functioning or in several.
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Only 5-10% of persons with MS develop problems severe enough to interfere significantly with everyday activities. In very rare instances cognitive dysfunction may become so severe that the person can no longer be cared for at home.
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Cognitive Functions Affected in MS
In MS, certain functions are more likely to be affected than others:
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Memory (acquiring, retaining, and retrieving new information)
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Attention and concentration (particularly divided attention)
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Information processing (dealing with information gathered by
the five senses)
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Executive functions (planning and prioritizing)
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Visuospatial functions (visual perception and constructional
abilities)
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Verbal fluency (word-finding)
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Certain functions are likely to remain intact:
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General intellect
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Long-term (remote) memory
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Conversational skill
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Reading comprehension
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The Relationship between Cognitive Dysfunction and other Disease
Factors
Cognitive problems are only weakly related to other disease
characteristics—a person with almost no physical limitations can
have significant cognitive impairment, while a person who is quite
disabled physically can be unaffected cognitively.
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Changes can occur at any time—even as a first symptom of
MS—but are more common later in the disease.
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Cognitive function correlates with number of lesions and
lesion area on MRI, as well as brain atrophy.
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Cognitive dysfunction can occur with any disease course, but
is slightly more likely in progressive MS.
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Being in an exacerbation is a risk factor for cognitive
dysfunction.
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Cognitive changes generally progress slowly but are unlikely
to improve dramatically once they have begun.
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The Importance of Early Diagnosis and Treatment
Early recognition, assessment, and treatment are important
because these changes—along with
fatigue—can significantly affect a person’s quality of life and
are the primary cause of early departure from the workforce. The
first signs of cognitive dysfunction may be subtle—noticed first by
the person with MS or by a family member or colleague.
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Difficulty finding the right words
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Trouble remembering what to do on the job or during daily routines
at home
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Difficulty making decisions or showing poor judgment
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Difficulty keeping up with tasks or conversations
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People with MS and their families should talk to the doctor if
they are concerned about cognitive dysfunction. A careful evaluation
is necessary to determine the cause(s) of mental changes since
cognitive function can also be affected by aging or medications, as
well as depression, anxiety,
stress, and
fatigue.
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A specially trained health professional (neuropsychologist,
speech/ language pathologist, or occupational therapist)
administers a battery of tests to evaluate cognitive dysfunction.
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Based on the test findings—including the person's cognitive
deficits and strengths—the health professional can provide
cognitive rehabilitation, including:
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Computer-mediated memory exercises
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Training in the use of compensatory strategies such as
notebooks, computers, and filing systems to compensate for
memory problems and other changes.
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Research on MS and Cognition
Studies are ongoing to identify ways to stabilize or improve
cognitive dysfunction. Since the disease-modifying drugs have all
been shown to reduce the accumulation of new demyelinating lesions,
it is likely they help to stabilize cognitive changes. However, more
studies are needed to determine their effectiveness in this area.
Symptomatic treatments that may temporarily improve cognitive
functioning without altering its long-term course have been studied.
To date the most successful has been donepezil hydrochloride,
showing modest improvement in verbal memory.
Studies funded by the National MS Society are investigating the
natural history of cognitive changes, along with better ways of
diagnosing and treating cognitive problems in MS. It is hoped that
in the future, people with MS will have access to a combination of
disease-modifying therapies, symptomatic treatments, and cognitive
rehabilitation that will modify the course and impact of the
cognitive changes in MS.
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