Multiple sclerosis (MS) is a progressive disease of the central nervous system that is well known for its effects on a person’s ability to move. However, one of the lesser-known symptoms of MS is cognitive decline — sometimes known as cog fog or brain fog. The term “cognitive” refers to how your brain thinks, learns, remembers, and understands things.

As MS progresses, approximately 40 percent to 65 percent of people diagnosed with the condition will experience cognitive changes. Additionally, research suggests that cognitive dysfunction can occur earlier in the disease than health experts once thought. These challenges can affect a person’s ability to work, drive, socialize, and live daily life independently.

How Does MS Affect Brain Health and Cognitive Functioning?

As we age, we all lose a small amount of brain tissue. This is known as brain atrophy. For people living with MS, this loss may happen at a faster pace, and connections in the brain can be disrupted. This doesn’t mean MS can cause dementia akin to Alzheimer’s disease. Dementia is typically more severe than the cognitive dysfunction seen in MS, but cognitive impairment in MS can still have a major impact on daily life.

In addition, the brain’s ability to adapt to MS damage (such as brain lesions) can be slowly used up over time. This decline in brain health results in worsening MS, including decreased mobility and cognitive deficits.

“I went to sign a check, and I couldn’t remember how to spell my own name!”

— A MyMSTeam member

The loss of myelin — a fatty layer of insulation found on brain cells or neurons — also contributes to a decline in cognitive functioning. Demyelination occurs during MS-related autoimmune attacks on the central nervous system.

What Are the Signs of MS Cognitive Symptoms?

It can be hard to recognize which changes are related to MS-related cognitive changes. Does MS affect memory? Can it make it harder to solve problems or think of words? While MS can cause symptoms such as dropping things, slurring speech, or muscle weakness, these are not considered cognitive issues.

The National Multiple Sclerosis Society describes six categories of cognitive symptoms.

1. Problems With Memory or Recall

Memory impairment can show up in many ways, including difficulty with learning new material, forgetting appointments or someone’s name, or feeling disoriented and not knowing where you are. One MyMSTeam member commented, “I went to sign my name on a check, and I couldn’t remember how to spell my own name!” Another member wrote, “I had to quit driving because I forgot where the places are that I have driven to for years!” Nearly 20,000 members of MyMSTeam have reported memory loss as a symptom of their MS.

“It’s like your brain is in slow motion.”

— A MyMSTeam member

2. Changes in Visual-Spatial Abilities

Transposing (changing the order of) numbers or letters, getting confused about directions, and having trouble with depth perception are examples of visual-spatial problems. Though transposing numbers can be a sign of dementia, it’s also a common issue for people with MS. One MyMSTeam member commented, “I’ve been transposing numbers for a long time. So aggravating! And I can’t remember phone numbers the way I used to.” Another member wrote, “Up, down, right, or left is something I have to think about, and it doesn’t come naturally.”

3. Challenges With Attention and Concentration

Some people with MS may have difficulty focusing or sticking to one task without getting distracted. Attention problems are a common component of MS. One MyMSTeam member shared, “I’m losing my train of thought.” Problems with focus may also be related to working memory, a type of short-term memory that’s involved with completing immediate tasks.

4. Trouble Processing Information

Trouble responding quickly to new information or handling deadlines can be signs that you’re having a hard time with information processing. “It’s like your brain is in slow motion,” a MyMSTeam member wrote. More than 2,800 members of MyMSTeam have reported experiencing slowed information processing speed.

5. Difficulty Problem-Solving and Dealing With Complex Tasks

Sometimes, a person with MS may have a difficult time problem-solving or managing complex tasks that may have been easier before MS. Missing the point in conversations, having difficulty with decision-making, or having trouble completing multistep tasks are examples. One member of MyMSTeam wrote, “Minor things completely overwhelm me.”

“I’ve been in therapy for cognitive difficulties, and it has helped. It’s a daily struggle to keep focused, but it’s working.”

— A MyMSTeam member

6. Issues With Verbal Fluency

Difficulty finding the right words or mixing up words are examples of declines in verbal fluency. “I can’t get my mind to spit them out,” wrote one MyMSTeam member. Word-finding problems have been reported by more than 5,700 members.

When Do MS Cognitive Symptoms Appear?

Cognitive symptoms may appear a year or more before your MS diagnosis, or they may come much later. Sometimes, cognitive changes may begin years before other MS symptoms become noticeable, meaning they can be an early sign of the disease. The course of your disease, whether relapsing-remitting or progressive MS, may also influence the timing of new or worsening symptoms.

The Importance of Early Intervention for Brain Health

If you or your neurology team is concerned about cognitive changes, cognitive testing can help identify any problems. However, you can make some important lifestyle changes to maintain your brain health as soon as you’re diagnosed with MS. These can include making changes to your diet and exercise regimen, as well as adding puzzles, video games, or other brain games to your daily routine to help keep your mind active and increase processing speed.

Starting a comprehensive treatment intervention plan early and sticking with it, along with lifestyle changes, may help slow MS and mental decline.

Cognitive rehabilitation therapy may also help. One member of MyMSTeam wrote, “I’ve been in therapy for cognitive difficulties, and it has helped. It’s a daily struggle to keep focused, but it’s working.”

Starting treatment for relapsing MS early may help reduce the frequency of MS relapses and the development of new brain lesions. This plan can also lead to a lower level of physical disability later in life (such as a decline in mobility). For example, some studies suggest that starting a disease-modifying therapy early may lead to better long-term outcomes for people with MS.

Although neuropsychological changes are a normal part of MS, you can take steps to protect your cognitive abilities and improve your quality of life. The first step involves talking to your neurologist about cognitive issues.

Adapting to Changes

Living with MS can be hard because the condition can affect so many areas of cognition and executive function (higher-order thinking). One member of MyMSTeam said, “I’m definitely functioning at a different level than I ever did. I’m forgetting things, constantly searching for words, and flat out do not have the attention span or even ability to read at the level I could 10 years ago. I’m still processing that loss. But knowing that it’s not coming back forces me to adapt and try to work through my new life.”

Building a Community

On MyMSTeam, the social network for people with multiple sclerosis and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with multiple sclerosis.

Have you noticed cognitive changes? How have they affected you? What steps have you taken to adapt? Share your experience in the comments below, start a conversation by posting on your Activities page, or connect with like-minded members in Groups.