Updated June 16, 2014.
Cognitive dysfunction as a symptom of multiple sclerosis (MS) may be the one that makes me the saddest. I can get angry at the “MS hug” and frustrated with trembling hands, but being mad at how my own brain and though patterns are misfiring is a little too complicated. It is also the symptom that is the hardest to talk about with people without MS, as it often comes across as a lame-sounding apology for being “ditzy” or is met with people mentioning how forgetful they have also become since they had children or turned 70.
Sure, we all misspell words sometimes or leave something off a list. However, many of us with MS have a moment that we can point to as evidence that the cognitive neurons are not as robust as they used to be. My “big moment” came when I intended to dash into a store to pick up some last-minute holiday wrapping supplies. I got into the middle of a big display area of giant shelves of shiny, colorful paper and ribbons – there was loud Christmas music blaring, twinkly lights blinking everywhere, and people grabbing at sale items while screaming at their out-of-school children. All of this “input” combined to not only completely make me forget what I came for, but to completely immobilize me. I don’t know how long I stood there staring uncomprehendingly at the whole scene before something jarred me back to reality and I fled from the store, empty-handed.
What Does It Feel Like?While cognitive dysfunction feels different for everyone and can change daily, many people with MS can identify with part or all of the following descriptions of MS-related cognitive problems:
- Problems with Abstract Conceptualization: Put simply, this is difficulty with figuring things out in the “abstract” in a way that is going to lead to a desired outcome. It means that people get easily overwhelmed if something is too complex, as it is hard to organize thoughts and tasks, to apply lessons learned from multiple past experiences, and to be “flexible” enough in their thinking to come up with alternate solutions if a problem arises. This can negatively impact judgment.
- Short-Term Memory Deficits: The most common form of cognitive dysfunction in MS, this usually manifests in things like forgetting whose number you just dialed, going to the pantry and not knowing what you went there for (even though you just looked at your recipe), or being unable to remember if you took your pills or not. You may also find yourself repeating a sentence or part of a story to someone that you just told it to, not aware that you had already said it.
- Attention Difficulties: This can manifest as “distractability” or simply inability to keep your mind on a task. You may find that you are unable to multitask or that even minor ambient noise, like the television or music, can make it virtually impossible to concentrate on things like reading or performing sequential tasks, like those involved in cooking.
- Slower Speed of Information Processing: This includes all the aforementioned symptoms, and it means that the brain simply cannot take in and prioritize all of the information coming at a person at once. This includes problems processing language (spoken or written), sensory information (visual, sounds, smells, touch), spatial information (like that involved in navigating while driving), or more abstract things like social cues and reading people’s emotions.
How Common Is Cognitive Impairment?Between 34 and 65 percent of people with MS have some sort of cognitive impairment. Even people who recently started having other MS symptoms may have cognitive dysfunction, but it might be so subtle that they didn’t notice it or attribute it to other things, such as aging or being tired.
What Causes It?Cognitive dysfunction in MS seems to correlate with more permanent destruction of brain tissue, such as “black holes” and atrophy. Therefore, cognitive dysfunction tends to be worse in people with progressive forms of MS than in people with relapsing-remitting MS. In general, people with progressive MS seem to be more severely affected (however, as mentioned, even people with very little disability can experience some degree of cognitive dysfunction). People with more pronounced cognitive dysfunction tend to have:
- More T1-Weighted Lesions: T1-weighted lesions in MS are areas that appear dark on MRI scans . These are also called “black holes” and indicate that there has been destruction of nerve fibers called axons, not just demyelination.
- Atrophy of Corpus Callosum: This means that the bundle of nerve fibers that connect the right and left hemispheres of the brain has shrunk, due to destruction of nerve cells.
- Depression: Depression, an extremely common symptom of MS, seems to impact cognitive function, especially in the areas of memory, attention and ability to concentrate. People who are depressed also often exhibit problems making good decisions, communicating and maintaining relationships with others and overall complex functioning, such as that required to make quick decisions and cope with complicated problems in everyday life.
- Fatigue: Fatigue is the most common symptom of MS, experienced by an estimated 85 to 95 percent of people with MS, and often considered the most debilitating. The crushing fatigue felt by people with MS can have a huge impact on how well we perform cognitively.
- Heat Intolerance: MS-related heat intolerance can make all symptoms of MS worse, including cognitive dysfunction.