Memory problems are very common in MS. The most common problem and usually the most problematic is rote memory. This is memory based on repetition. It often refers to isolated facts, that is, facts with no necessary logical connection to other facts, like a date or like an address of someone you just met. It doesn’t automatically connect to other facts. This known as “rote memory”. Rote memory items are more difficult to learn than items that relate, more or less logically to existing systems. Learning facts that attach logically to other facts or to a system of facts is much easier. The brain has what I would call a random access memory which means that a fact that logically connects to multiple other facts is much easier to recall than isolated facts.
In many occupations, there is a logically connected series of things that you do which I will call a “framework”. You can connect to the framework with information that logically connects to it so that, for the new connected items, recall is relatively easily because of the logical connections.
Even for people with a good memory, disconnected facts and facts out of context can be a problem. A personal example is my difficulty remembering names. As an intern, if you gave me one unique bit of information from a medical history, I could connect it and give you an essentially complete history but if you gave me the person’s name in isolation, I couldn’t connect it to the history.
Another way to think of human memory is how easy it is to recall your mother. You have thousands of ways to access her memory. On the other hand, it may be very difficult to recall someone you just met casually last week. Memory experts will tell you that you have to make multiple connections to remember people’s names such as she wore a dress like one I have seen on my friend Mary and a scarf I used to have and her eyes look just like Jessica’s. Now you have a few connections and the more you have the easier it is to remember the name.
One result of this is that totally new things are much harder to remember than things that fit into a system. Many MS specialists have patients who actually took a demotion or refused a promotion because of the difficulty of learning a new system even though they were outstanding in their work on a known system.
There are also other problems with thinking and memory. When I am walking, I often think about things I have just heard, developing their relationship to known facts thus consolidating memories. If you have walking difficulty, you have to think about walking rather than what you will do next. A neurologist friend of mine, Dr. Herman Buschke devised a test called “Walking While Talking”. This is a “divided attention” or “multitasking” type of problem. A person does a timed walk for 20 feet and returns for a total distance of 40 feet. First he is simply walking. Next, he does it while reciting the alphabet or doing a more complex task such as reciting alternate letters in the alphabet. This has little effect on normal individuals but, if there is difficulty with walking or with balance, the walking speed is slower and may involve brief stopping. This test was designed for frail and impaired elderly but we see the same effect in people with MS. It is a form of “multi-tasking” and it has been shown in a number of physiological studies that even simple tasks require activation of more, often much more, of the cerebral cortex in people with moderate to advanced MS than in normal individuals.
Why does MS cause these problems? First, when a normal pathway is interrupted as often happens in MS, the brain must find a way around the problem. This often involves the transmission of information by different and longer routes. This likely involves multiple connections through shorter pathways and this takes longer. Thus thought process and information processing is slowed.
Concentration involves the brain ignoring other things. This is not as often thought, a passive process, it is an active process that actually can partially shut off auditory input. This is often impaired in MS and things that normally wouldn’t interfere with cognitive activities become a problem. Many years ago, i was visited by a couple from Australia who were visiting in the states and seeing a number of MS specialists. One of their problems was that the husband who had MS was always irritable and frequently upset and angry. If memory serves, they had three teenagers who were noisy and he usually spent his time in a chair in the living area which was open to the kitchen and the children were in and out, often playing loud music, talking and joking. I explained that this would be overwhelming to almost anyone but was particularly distressing to those with MS. I strongly recommended that he have a quiet room where he could read or watch TV. If one of the children wanted to talk to him they could go in and talk to him, but only one at a time. A year later I got a long distance call from one of the most grateful couples I can imagine. They had followed the advice and it had totally changed their relationship.
In another instance, I had a patient who had performed extremely well in a quiet office but simply could not function at a busy counter in the front of the office because too much was going on simultaneously and she couldn’t manage the distractions.
The cognitive problems in MS, unless very advanced, are not really a form of dementia but are composed of several different problems that arise in the process of compensating for the various deficits and damaged pathways that slow mental processing and interfere with normal brain function.
Too much information can be confusion. Many people with MS become very uncomfortable in supermarkets, drugstores and malls. If you think about a supermarket, every item in it is vying for your attention. There is an enormous amount of information coming in, too much for the individual to process. As a result, many people give up shopping or limit it as much as they can.
Cocktail parties and similar events are often a problem. Shutting out competing conversations is difficult for many of those with MS. This may result in sharp restriction in their social life and can lead to agoraphobia (fear of going out or of large groups). They often can function better in small intimate groups where there is only one conversation going on at a time.
Understanding the nature and type of cognitive problems often allows for accommodation that will allow a person to continue in the work force.