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  • More than 50 percent of people with multiple sclerosis (MS) experience cognitive changes.
  • Sometimes cognitive changes are the first sign that you have MS, although they are more likely to occur later on, as the condition progresses.
  • These changes can happen with any type of MS but are more common in progressive MS.

Your brain is the most complex organ in your body. It performs a long list of functions critical for life.

This is possible because of electrical impulses that travel through nerve cells called neurons. Each neuron has a tail-like axon that carries those impulses to the next cell. Axons have a protective covering called myelin, which speeds up the signal transmission.

If you have multiple sclerosis (MS), your immune system mistakenly targets the myelin in your brain and spinal cord. This interferes with the transmission of nerve impulses and causes MS symptoms.

Your brain is about 20 percent myelin. When MS interferes with the function of this myelin, it can disrupt the neuronal activity in your brain. As a result, more than 50 percent of people with MS experience some cognitive changes.

Sometimes cognitive changes are the first sign that you have MS, although these types of changes are more likely to occur later on, as the condition progresses. These changes can happen with any type of MS but are more common in progressive MS.

Some of these changes can affect:

  • concentration and attention
  • information processing
  • memory
  • prioritizing and planning
  • verbal fluency
  • visual spatial ability

According to one study, roughly 40 percent of those with MS will have only mild symptoms, but 5 to 10 percent will have moderate to severe symptoms. Those with progressive MS tend to experience more severe cognitive changes than those with relapsing-remitting MS.

During an MS flare, inflammation can trigger new cognitive challenges, or intensify the ones you already have. Sometimes these flare-related changes are permanent, but they can also resolve once the flare has passed and the inflammation has subsided.

Brain fog is a term used to describe how your brain doesn’t seem to work as well as it once did. It’s also sometimes referred to as “cog fog,” the shortened version of cognition fog.

When you experience brain fog, you might forget words, lose your keys, or miss an appointment. Your job performance or schoolwork may be affected, or you might be challenged by everyday tasks, like decision making.

Brain fog can be your first MS symptom, or it can appear after you have a diagnosis. Brain fog can interrupt your daily routine by causing you to become absentminded. Strategies to manage brain fog include:

  • writing to-do lists
  • using voice-to-text technology to keep notes
  • using timers and alarms
  • using a family calendar
  • saving difficult tasks for when you’re most alert
  • reducing background noise when you need to concentrate
  • designating a specific area in the home for important items, like mail and keys
  • avoiding multitasking
  • taking frequent breaks to recharge

If you have an MS diagnosis and begin to notice cognitive changes, it’s important to talk with your doctor to assess the situation. Early screening and ongoing monitoring can help those with MS manage their symptoms.

Cognitive changes can vary widely from person to person, depending on how severely the brain has been affected.

Once a doctor has determined your cognitive strengths and deficits, they may recommend a cognitive rehabilitation program to help prevent symptoms from worsening. In some cases, these programs can result in some improvement.

These programs usually consist of:

  • restorative activities, including learning and memory exercises
  • compensatory activities, to help make up for functions that no longer work so well, such as using a central calendar, and using notes or checklists to remind yourself of important events

According to the National MS Society, some central nervous system stimulants may also be helpful in improving attention, processing speed, and memory problems.

In addition, many disease-modifying treatments (DMTs) for MS reduce the accumulation of new demyelinating lesions, so it seems likely they may be able to help stabilize cognitive changes. However, more studies are needed to determine their effectiveness in this area.

Someday, a combination of rehabilitative programs, symptomatic treatments, and DMTs may help to modify the course and impact of cognitive changes related to MS.

Brain lesions cause brain fog. The more brain lesions a person with MS has, the greater the number of cognitive changes they will likely experience.

MS lesions are areas of injury that occur on nerve cell myelin. They appear when white blood cells and fluid trigger inflammation that damages the myelin and the axons underneath.

Lesions affect the transmission of nerve impulses. They can slow nerve signals or block them completely. The signal interference they cause can happen intermittently or constantly.

There is no specific order or pattern for MS lesions to occur, which is why not everyone with MS has the same symptoms. Lesions can vary greatly in size and shape. They can develop anywhere in the central nervous system (CNS), and their location determines the changes you experience.

Treatment aimed at slowing the formation of new lesions can also help to slow the rate of cognitive changes.

If you begin to experience cognitive changes or have concerns about developing them, talk with your doctor. They can perform a short screening test, and depending on the results, they may refer you to a specialist for a more comprehensive evaluation.

A comprehensive evaluation will help point out exactly what specific cognitive functions are affected. It’s also important to make sure that these changes are related to demyelination and aren’t the result of other issues, such as fatigue, medication, or mood changes due to depression, anxiety, or stress.

MS is a condition affecting myelin. The area of your brain containing the most myelin is called white matter. This is the area underneath the grey matter surface. Grey matter contains most of the neuronal cell bodies, while the myelin-coated axons extend through the white matter and connect areas of grey matter.

Previously, MS was thought to affect mostly white matter in the brain. This is because grey matter doesn’t have as much myelin, so grey matter lesions are hard to see in medical imaging. Since newer imaging technology can detect some grey matter lesions, we now know that MS affects both white and grey matter.

Cognitive impairment symptoms depend on the presence of lesions in specific brain areas. For example, lesions in the brain’s frontal lobe region can interfere with executive function skills like decision making and prioritizing. Lesions located near the cortex may cause memory issues.

MRI technology can detect MS lesions. This type of scan is used to diagnose MS as well as monitor its progression by keeping track of any new lesions that may have occurred since diagnosis.

An MRI scan can also reveal if any existing lesions have increased in size. In addition, it allows doctors to monitor the location of lesions and the areas of the brain that may be potentially affected.

The specific location of lesions may also give doctors information about possible related cognitive issues to watch for.

MS symptoms are caused by the location of lesions, which slow or block nerve signals. They can occur anywhere in the CNS at any time, so symptoms can vary widely for people with MS.

If you have MS lesions in your brain, you might experience cognitive issues, also known as brain fog. About half of people with MS experience these cognitive changes.

If you begin to experience cognitive changes, it’s important to talk with your doctor and be screened to understand what’s causing them.

In addition to treatments that may help stabilize or improve symptoms, doctors can also recommend strategies to manage these changes, including using timers, making lists, and taking notes. Taking breaks to rest your mind can also help.