How Common is Cognitive Impairment in MS?
Approximately one-half of persons with MS experience some degree of cognitive impairment. Of the MS patients with cognitive dysfunction, most (80 percent) exhibit relatively mild symptoms such as difficulties remembering lists of food items to buy in the supermarket or performing tasks in distracting environments. Most patients can learn ways to compensate for these nuisance symptoms (see below). The remaining 20 percent experience more serious cognitive problems that may interfere with their ability to work and engage in everyday activities such as cooking and driving.

Causes of Cognitive Impairment in MS
Many factors can cause cognitive impairment. Stress, anxiety, and depression can decrease our ability to remember, pay attention, and solve problems. Similar impairments can occur as a side effect of some types of medications. We are also quite aware that our ability to pay attention and retrieve information declines as we get older. But, in MS, the cause of cognitive dysfunction is directly related to changes that occur in the brain. MS produces changes, called lesions, in the white matter of the brain. These lesions affect the way electrical impulses are transmitted across nerve cells. The lesions can be visualized with magnetic resonance imaging (MRI). Almost all patients with MS have some brain lesions on MRI scans. Research has shown that the degree and type of cognitive impairment observed in MS patients is related to the amount and location of the lesions in the brain. Thus patients with a small number of lesions may not experience any cognitive dysfunction, whereas persons with a large number of lesions are at high risk for experiencing cognitive problems.

How Do Cognitive Impairments in MS Differ From Other Conditions Such as Alzheimer's Disease?
For most patients with MS-related cognitive impairment, the deficits are mild and do not necessarily progress for long periods of time, if at all. This contrasts with Alzheimer's disease, where afflicted individuals experience severe cognitive deficits that invariably get worse with time. MS and Alzheimer's patients also differ in the way memory and language functions are affected. In the area of memory, patients with Alzheimer's disease experience difficulties storing new information. As a result, they may not benefit from receiving reminders from others or from using notes to aid their recall. In contrast, persons with MS can store new memories and are capable of learning new information, but have problems spontaneously retrieving this information. MS patients are capable of benefiting from reminders and visual aids. Alzheimer's patients can experience severe problems in using language to communicate (called aphasia); it is very rare for an MS patient to have language or communication problems.

Diagnosing Cognitive Impairment
Cognitive impairments are typically diagnosed as part of a neuropsychological examination. Neuropsychology is a subspecialty field within clinical psychology that is devoted to the diagnosis and treatment of cognitive dysfunction. A clinical neuropsychologist will administer a battery of cognitive tests and compare the results to a normative sample of healthy individuals of the same age and educational level as the person being evaluated. This examination can be lengthy (three to five hours), but it can provide information and useful recommendations to the patient, family, and treating physician. Such an evaluation is often requested by the patient's physician, although occasionally a patient may contact a neuropsychologist directly.

Are Cognitive Impairments an Inevitable Part of MS?
Some MS patients experience cognitive dysfunction very early in their disease, whereas other persons may never experience such problems. Over a three year period, approximately 20 percent of persons with MS will experience the emergence of new cognitive symptoms or a worsening of their existing cognitive symptoms. The patients who experience a worsening of cognitive symptoms tend to be the patients who acquire new brain lesions. It should be noted that there is very little relationship between the degree of physical disability and the degree of cognitive impairment. As a result, a person with significant physical symptoms (problems with walking, coordination, visual or tactile sensory disturbance, bowel or bladder dysfunction) may experience no problems with cognition, but a person with little outward signs of physical disability may have significant cognitive problems. Likewise, an acute worsening or exacerbation of physical symptoms may not affect cognitive functions, and vice versa.

How to Cope With Cognitive Impairments
Most patients can compensate for their memory problems by relying more on visual cues such as post-it notes, calendars, date books, and day planners. An electronic organizer, such as a Palm Pilot, or a handheld tape recorder can be particularly helpful. Making lists will help to organize and prioritize information, errands, tasks and other details and will aid recall. It is important to check items off as you accomplish them. There's also nothing wrong with requesting relatives and loved ones to call you with reminders about upcoming events and appointments. Exercising the mind—reading newspapers and books, playing cards, doing crossword puzzles, engaging in stimulating conversation—can also be helpful. For people with attention problems, directing concentration on a single task is preferable to doing too many things at once. When engaging in tasks requiring intense concentration, try to avoid noisy or distracting environments.

For MS individuals with more severe cognitive problems, cognitive retraining programs are available through most medical centers. Typically these programs are conducted by rehabilitation specialists from a variety of disciplines, including clinical neuropsychologists, speech pathologists, and occupational therapists.

Are There Any Medications Designed to Treat Cognitive Impairments in MS?
Currently, there are no approved medications for treating the cognitive problems in MS, although one double-blind clinical investigation currently in progress is designed to assess the effects of Aricept in improving memory functions in MS. Aricept is currently approved by the FDA for treatment of cognitive dysfunction in Alzheimer's disease. Results from the clinical trial involving Aricept in MS patients will be known within the next one to two years

Medications Designed to Prevent the Development of Cognitive Impairments in MS
An alternative approach is to prevent the development of cognitive problems in MS. As noted above, patients with many brain lesions are more likely to experience cognitive problems. Furthermore, MS patients who acquire new lesions tend to experience a worsening of their cognitive symptoms. It stands to reason that any drug that prevents or slows down the development of new lesions in the brain is likely to prevent or slow down the progression of cognitive dysfunction. There are three FDA-approved medicines for treating patients with MS: Avonex, Betaseron, and Copaxone. These agents work by altering the body's immune system to prevent or reduce MS exacerbations. In two double-blind studies, patients treated with Avonex and Betaseron experienced less cognitive impairment than patients receiving a placebo. The Avonex study, which involved a large patient sample, resulted in a significant 47-percent reduction in the number of patients showing deterioration of cognitive functions. In contrast, a similar study involving Copaxone showed no effect on cognitive functions.

Summary
Approximately one-half of MS patients experience some form of cognitive impairment, primarily in the areas of attention, memory, and problem solving. The primary cause of the cognitive impairment is the buildup of MS lesions in the brain. In most patients, the problems are minor and can be compensated for by making changes in the home and work environments. More severe cognitive problems can be treated with cognitive retraining programs. Cognitive dysfunction can occur early in the disease, but is not inevitable. The diagnosis of cognitive dysfunction is typically made by a clinical neuropsychologist. Proven treatments of cognitive dysfunction with medicines are not available, although drug testing is currently underway. Prevention of cognitive dysfunction can be achieved with disease-modifying treatments designed to alter the body's immune system to prevent the build-up of new MS lesions in the brain. If you have MS and think you may be experiencing problems with cognition, it is important to discuss this with your physician.