How typical is cognitive impairment in MS?
Cognitive deficits are not the most typical symptoms of MS. In fact, severe cognitive impairment that makes everyday coping difficult is reported in 10 per cent of people with MS, whereas an estimated 40-50 per cent experience mild to moderate disturbances. This means that about half of those diagnosed with MS never experience cognitive impairment.
Even mild impairment may require changes in a person’s routine and habits. For example, coping at work may require extra effort and the use of aids or compensatory techniques. If cognitive deficits are not identified properly, they may be a cause for stress and misunderstanding at work and at home. They should, therefore, be recognised as early as possible, so that steps can be taken to ease the situation.
What kind of cognitive impairment is associated with MS?
The most common types of memory problems are difficulties in remembering recent events and remembering planned or necessary tasks. Some people with MS also report that it takes more time and effort to find misplaced items and to remember new information.
Some people find it difficult to concentrate for long periods of time or have trouble keeping track of what they are doing or saying when distracted or interrupted, for example, carrying on a conversation while the TV or radio is on. Moreover, many people describe feeling as though they cannot function as quickly as they could before MS.
Some people experience difficulties when planning and problem solving. People with these types of problems usually know what should be done but find it difficult to know where to begin or to work out the steps involved to achieve their goal.
People with MS may also experience difficulties in word-finding, reporting that a word or name is “on the tip of my tongue”. The person knows the word but is unable to retrieve it.
MS can lead to other types of cognitive problems. One well-known study reported that visuospatial abilities are affected in up to 19% of people with MS. However, deficits in language are less frequent. Furthermore, severe cognitive decline or dementia, such as that commonly seen in Alzheimer’s disease, is rare in MS.
Are cognitive deficits predictable and do they progress?
It is not possible to predict from other symptoms of MS whether someone is likely to suffer from cognitive impairment or not. Cognitive problems do not seem to be related clearly to such disease variables as duration, severity or disease course. Cognitive deficits may be present during the early stages of the disease, as well as later on, in mildly or severely physically disabled patients. Cognitive impairments have no known link to any single physical symptom of MS. However, sometimes dysarthria (poorly articulated speech), ataxia (problems with co-ordination) or nystagmus (rapid involuntary eye movements) may be falsely interpreted as a sign of cognitive impairment.
It has been found that cognitive deficits are more common in people who have changes in the cerebrum than people who have changes in the cerebellum, brainstem and spinal cord alone.
Unfortunately, little information exists about the progression of cognitive impairment in MS. It has been found that cognitive performance can vary during even short follow-up periods. Recent studies show that if a person experiences some cognitive problems, worsening is possible, although the rate of progression is usually slow.
Are cognitive problems permanent?
Whereas brain lesions can result in more permanent cognitive problems, a number of factors can interfere with or impair cognition temporarily. These factors include fatigue and tiredness, emotional changes, MS relapses, physical difficulties that may require extra effort and concentration (such as unstable walking), medications and lifestyle changes, such as having to leave employment and therefore having less mental stimulation.
Living with a chronic, progressive and unpredictable disease inevitably affects a person’s mood. When people are depressed or feeling low, they may experience memory lapses or problems concentrating. Usually these difficulties are not long-lasting. Many people with MS report cognitive problems during periods of fatigue, and recent studies have shown that cognitive performance may be slowed or be less accurate when the person is experiencing fatigue. Temporary cognitive difficulties may also occur during relapses. Just as with physical symptoms, cognitive problems may be restricted to the active inflammation phases of the disease. Cognitive functioning can be affected by several factors, so it is not usually appropriate to evaluate cognition if the person is experiencing depression, a relapse or excessive stress.
Evaluating cognitive problems
Even mild cognitive impairments can cause feelings of uncertainty and fear. It is important to know that these symptoms, just as with bladder problems, or difficulty walking, are part of the disease and that there are ways to live with them.
Since realistic information can help a person to cope with a new situation, it is important that each person diagnosed with MS receives information about cognitive impairment. Cognitive problems are evaluated with a neuropsychological assessment, which includes testing and a detailed interview. The goal of neuropsychological assessment is to individually evaluate the severity and characteristics of cognitive impairment. Furthermore, an individual’s cognitive strengths can be identified and strategies to alleviate the effects of impairment can be suggested.
Not everyone necessarily requires a neuropsychological assessment. Many people can identify for themselves the individual areas that are causing problems and work out ways to deal with them. Neuropsychological assessment is important when evaluating ability to work, possibilities for re-education or driving ability. An assessment should also be performed if cognitive impairment continuously interferes with a person’s daily activities and/or social interactions.
The role of neuropsychological testing in research
Neuropsychological assessment has been employed for study purposes in evaluating the frequency, the characteristics and natural history of cognitive impairment, as well as its relationship to other disease variables. Studies on cognitive functioning in MS have been able to show the effects of cognitive impairment on employment, driving skills, personal independence, etc. Many recent studies have evaluated the effectiveness of medications and different rehabilitation methods on MS-related cognitive deficits. These kinds of studies have made it possible to develop methods to alleviate the effects of cognitive problems.
Current understanding of MS and cognitive changes
Much of our understanding of cognitive changes related to MS has come from scientific research. Here are some general statements we can make based on current knowledge in this area:
• There is little or no relationship between duration of the disease, or severity of physical symptoms, and cognitive changes.
• People with a progressive form of the disease are at a slightly greater risk of cognitive changes, although those with relapsing-remitting MS can have difficulties.
• Cognitive problems can worsen during an exacerbation and lessen with remission, although the changes in these symptoms appear to be less dramatic than those seen with physical symptoms such as walking and vision.
• Cognitive changes can and do progress like other symptoms, but the worsening appears to be slow in most cases.
Source: Multiple Sclerosis: A Guide for Families, Rosalind Kalb, Ph.D., Demos Vermande, 1998 p.24