Cognitive Dysfunction in Multiple Sclerosis

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Cognitive Dysfunction is one of the more scary symptoms of Multiple Sclerosis. It used to be thought that cognitive dysfunction was relatively rare symptom of the disease but it is now understood to be quite a common feature.

Among the reasons that it's frequency was formerly underestimated is that the dysfunction is often mild, cognition is a very complex subject and, in the past, physicians have felt more comfortable denying its existence to their patients. Things have changed over the past few years. Rather than lumping cognitive dysfunction in the same bracket as fatigue and depression, it is now studied on its own. Cognitive evaluation techniques have also improved greatly and now proper studies into cognitive dysfunction in MS are beginning to be done.

It is important to understand the nature of the range of cognitive problems associated with MS. Dementia, as we understand it from diseases like Alzheimer's disease, CJD and Huntington's Corea is really quite rarely seen in multiple sclerosis. When it does occur, it is known as Cerebral Multiple Sclerosis and occurs in around three per cent of people with MS and usually only in the later stages of the disease. Less severe dysfunction is estimated to occur in 54 to 65% of people with MS.

As with other dysfunctions in MS, cognitive ones tend to be seen within specific intellectual functions. A person with short-term memory deficits may or may not have problems generating concepts - just as a person with spasticity in their right leg may or may not have double vision.

A very commonly observed feature across the range cognitive dysfunctions seen in MS is that performance accuracy is rarely affected. What tends to be damaged is the speed of performance. For example, in memory tests, people with MS may remember fewer numbers than other people but the numbers that they do remember are correct.

They may be slower at doing certain tests but they get them right eventually. This is, perhaps, to be expected because multiple sclerosis is a white matter disease and rarely affects the grey matter. As a gross simplification, we can say that the grey matter is responsible for the processing and the white matter for passing the results of that processing to other parts of the brain.

Cognitive dysfunction is most severe in people with the Secondary Progressive form of the disease. Although some studies show that as many as 50% of people with MS have some form of impairment from disease onset, it is usually mild and often recovers with remission. Perhaps because the Primary Progressive form prefers to attack the spinal cord, people with this form have been shown to be more rarely affected by cognitive impairment.

It is worth noting that a recent comparative study of cognitive dysfunction in depression, MS and chronic fatigue syndrome found that people with depression performed less well on most of the tests than people with MS. Medications used to treat some of the other symptoms of MS also affect cognitive performance.

One study found that people who had mild cognitive deficits early in their disease course were more likely to have more marked dysfunction later on. Another study found that cognitive dysfunction was unrelated to Expanded Disability Status Score which is essentially a measure of physical disability. Total lesion load was found to be correlated with level of cognitive dysfunction but not with lesions in specific brain areas. This is not surprising given the complexity and plasticity of the human brain.

Some of the specific cognitive deficits observed in people with MS are:

* Memory Dysfunction. This is the most commonly reported cognitive dysfunction in MS and occurs in 20 to 44% of people with MS. The type of memory deficit most often reported is free recall of recently learned material. Free recall is the ability to get to a memory instantly - MS rarely seems to affect a person's ability to get items into the memory banks - just our ability to get it out "right now". What also does not appear to be compromised very often is a person's ability to understand and learn new concepts nor the speed at which they do so.

* Verbal fluency is affected in some people with MS whereas verbal comprehension appears undamaged. Verbal fluency deficits usually take the form of slowed free recall of words that describe concepts and less often words that name objects.

* Cognitive Fatigue. On average, people with MS tire more quickly during psychological tests and often start off matching control subjects but their performance tails off as the test progresses.

* Impaired Planning Skills. One study reported that 40% of people with MS are less able to plan things than healthy controls. This study was criticised because it was a timed test and that the people with MS all had the Secondary Progressive form of the disease.

These findings are all drawn from the results of psychometric tests - some of the problems cognitive dysfunction causes in a person's everyday life include forgetting:

* whether they have taken a medication
* some of the things that they have to do on a particular day
* what they went into a room to get
* to shut the windows when they leave the house
* a word that they know very well
* to take a new route on a particular journey rather than follow the usual route

There are a number of strategies that people with cognitive dysfunction can use to get around it. These include:

* Write everything down. Rely heavily on a diary, loose-leaf organiser and/or palm-held computer/organiser. This latter is an excellent tool and can be programmed to remind you of things you must do with a bleeping sound. Personally, I find my large year planner pinned on a wall an invaluable aid - I keep its marker-pen on a pinned-up piece of string so it doesn't get lost - it is my bible and tells me what I have to do.

* Have a particular place for everything and always put things back where they belong and encourage others to do the same. This way you don't need to remember where you put your keys or spectacles because they are always in their homes.

* Try to focus your attention more keenly on the things that are important. We are often used to paying things half a mind and then forgetting about them. Repeating important things that need to be remembered over and over in your head will often keep them there. People with MS often report that external noises distract them from paying attention to anything at all - exercises that improve your focus can improve concentration.

* Try to jot everything down, including people's names and how they appear to you. Often just the act of writing something down will commit it to memory better. Pictures also help. These can be mental or drawn.

* Word recall is a problem that is often reported in MS. If you suffer from this, try not to get hung up about the exact word. People are often happy to chime in with the right word anyway - let them.

* Work slowly. Take your time to plan things and don't be rushed by anyone. Use paper and/or a calculator as necessary.