UNDERSTANDING COGNITIVE DEFICITS is important for family members who are trying to cope with these changes. Much of our understanding has come from scientific research, especially during the last 20 years. What follows is a brief summary of some of that research.
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Cognitive changes can affect anyone with MS, whether they have had the disease for 30 years or 30 days and whether they are confined to a wheelchair or running a marathon. In other words, there is little or no relationship between duration of the disease, or severity of physical symptoms, and cognitive changes.
Although people who have had MS for a long time, or have a progressive course, are at slightly greater risk for cognitive changes, even those who are recently diagnosed and/or have a relapsing remitting disease course, can have such deficits. Cognitive deficits can worsen during an exacerbation and lessen as a remission sets in, although the fluctuations in these symptoms appear to be less dramatic than the changes seen in physical symptoms such as walking and vision. Cognitive changes can and do progress like other MS symptoms, but the progression appears to be very slow in most cases. One major study in this area found very little progression over a 3-year period.
Much of the research on cognition in MS has used neuroimaging techniques, especially magnetic resonance imaging (MRI). There is a strong relationship between cognitive changes and the amount of demyelination that has taken place. Some research has also attempted to relate demyelination in specific locations of the brain to particular cognitive deficits. This type of research is challenging because most people with MS have demyelination in a number of locations in the brain. Some interesting findings, however, have begun to emerge.
- The right and left halves of the brain are connected by a structure called the corpus callosum. When this structure is extensively demyelinated, people with MS are likely to experience slowed information processing, memory loss, and difficulty with tasks that require the left and right sides of the brain to work together.
- When the frontal lobes (areas just behind the forehead that are responsible for thinking and reasoning) are significantly demyelinated, there tend to be problems with memory and executive functions - for example, the ability to organize, sequence, prioritize, initiate, and follow through on a complex sequence of tasks leading to a specific goal.
"Functional" MRI studies have begun to show that during certain cognitive tasks, the brains of people with MS actually behave differently than brains of people without the disease. Areas of the brain that are typically "activated" during certain types of tasks are less activated among individuals with MS. Moreover, areas of the brain that are normally inactive during those same tasks do become activated, almost as if the brain were compensating by shifting gears to get the job done.
Evaluation
THE FIRST STEP in dealing with cognitive changes is to recognize that they have occurred. People with MS often find that others do not take their complaints about cognitive loss seriously. Well-intentioned family and friends will say things like, "Oh, I forget appointments, too. That happens to everybody...." or "We're just getting old!" Such reassurances tend to trivialize and invalidate what is a very real set of problems based on a specific neurologic disease - problems in a different class entirely from those due to human frailty, imperfection, and aging. Unfortunately, physicians often reinforce these denials by the use of very brief "mental status" examinations that fail to detect any but the most extreme cognitive changes. Research has shown that such mental status examinations miss at least 50 percent of the instances of cognitive change in MS.
Adequate assessment of cognitive deficits in MS may require an extensive battery of neuropsychological tests. Such batteries can last from 6 to 8 hours or more and cost upward of $2,000. Briefer screening batteries have been developed, which use a carefully selected set of standardized tests shown to be effective in summarizing the results of the longer batteries. Ideally, the evaluation should be done by a psychologist or neuropsychologist who is experienced in MS, although some speech-language pathologists and occupational therapists perform similar types of evaluations.
In addition, it is important to assess other psychological factors such as depression and anxiety that may be contributing to cognitive problems. Such an evaluation should probably be done by a psychiatrist or a neuropsychiatrist, a specialist who has had training in both neurology and psychiatry. A good assessment will let you know where you stand and provide the starting point for planning treatment, career change, vocational rehabilitation, and improved family dialogue. To find out more, you can check out Liberation Treatment For Multiple Sclerosis.