MS and Dementia

Medically Reviewed by Christopher Melinosky, MD on June 06, 2024
8 min read

Cognitive impairment is a common symptom for people with multiple sclerosis. Up to 60% of people with MS have some type of cognitive function symptoms, such as:

  • Fuzzy thinking, or “brain fog”
  • Loss of memory or recall, not being able to come up with the right word in conversation or forgetting a past event
  • Trouble multitasking, making a plan, or soaking up new information
  • Changes in vision, like not being able to judge how far away or deep things are
  • Attention lapses

Is an occasional memory lapse a sign of the start of dementia with MS? If you’re diagnosed with MS, are you more at risk for dementia? These two conditions may overlap in some people, but cognitive impairment in MS isn’t the same as dementia, a more severe cognitive condition seen in people with Alzheimer’s disease.

Most people with MS who have cognitive changes don’t have the more severe loss of mental function or control that happens in dementia, like Alzheimer’s disease. But these symptoms can still affect your quality of life and day-to-day activities at home or work.

Dementia is not one disease. It’s an umbrella term for a severe loss of mental function. Dementia means a severe loss in the ability to think, reason, plan, or remember. It interferes with your daily life and ability to live independently. Dementia can also cause severe emotional symptoms and changes to your personality.

Dementia is caused by physical changes in your brain due to many different diseases. Alzheimer’s disease is the most common cause of dementia. About 60% to 80% of people with dementia have Alzheimer’s disease.

Lewy body dementia, frontotemporal dementia, vascular dementia, Parkinson’s disease, and Huntington’s disease are other diseases that cause dementia. Other people can have mixed dementia or dementia caused by more than one disease.

Your level of cognitive impairment isn’t tied to how long you’ve had MS or how much physical disability you have. You or your family may first notice that you can’t come up with a phrase or you lose your focus soon after you’re diagnosed with MS or many years later.

Cognitive changes usually affect people after they’ve had MS for years. If you have cognitive changes earlier with MS, it’s not a sign that your physical disability will worsen, like not being able to walk on your own or take care of yourself.

People with progressive forms of MS, like primary progressive MS or secondary progressive MS, are at a little higher risk for cognitive symptoms than people with relapsing-remitting MS.

It’s rare for someone with MS who has no physical symptoms or very mild physical disability to have severe or disabling cognitive changes. If that happens, your doctor may suspect another cause for these mental symptoms, such as some form of dementia, infections, or metabolic disorders that affect the brain.

MS causes inflammation that attacks and wears down myelin, a protective tissue wrapped around your nerves. Over time, your myelin and nerve endings that send signals back and forth in your brain and nervous system become damaged.

Scar tissue or lesions can develop in areas of your brain. Cognitive symptoms in MS are caused by this damage in your brain and nerves. Your cognitive dysfunction is linked to these lesions, including how many you have and where they are in your brain’s white or gray matter. Changes to your brain’s structure from MS, or brain atrophy, also cause these cognitive declines.

Cognitive impairment in MS isn’t the same as the more severe dementia in Alzheimer’s disease. It’s more like changes in your mental function. Most people with MS have mild cognitive changes, or just one or two cognitive symptoms.

Mild cognitive impairment in MS is when your mental function or mood changes are not noticeable in passing conversations with people, like a clerk at a store or your delivery person. Your family, close friends, and co-workers who see you often may be more likely to notice changes in your thinking, moods, or memory.

MS is unlikely to cause more severe cognitive changes, like loss of your intelligence, long-term memory, ability to have conversations, or ability to understand something you read.

MS cognitive symptoms can affect your quality of life, self-image, and mood. These changes can affect your ability to do your job, have conversations, enjoy social activities like parties or sports, or pay attention and focus on tasks at home, the office, or in the yard.

Some people with MS stop working because of cognitive impairment. This can lower your self-esteem and sense of pride in being able to support your family, and it can mean a loss of income. When you stop working, you also lose a valuable social network of co-workers or customers. You can become lonely or feel cut off from the world.

MS cognitive impairment can affect your relationships with family members, too. Your spouse, partner, or children may have to take on more responsibility at home or feel more pressure to be breadwinners. They may have to help you with some tasks you used to manage on your own. This can create stress in families or relationships.

Severe cognitive impairment that seems like dementia is rare in people with MS, especially if they don’t have severe physical problems too.

One important risk factor for severe cognitive impairment in MS is smoking. Many people with MS who develop more severe cognitive changes are either current or former tobacco smokers. Smoking also increases your risk of brain atrophy, which is one cause of cognitive impairment in MS.

People with primary progressive MS (PPMS) may have progressive memory loss and mild to moderate loss of attention and focus that seems like dementia. These may be due to lesions and reduced blood flow in areas of the brain like the frontal or temporal lobes, as well as the white matter. It’s possible that PPMS could be mistaken for dementia.

Mild cognitive impairment in MS isn’t the same as dementia, which is more severe.

Dementia is caused by damage to nerve cells in your brain. In dementia, you have more nerve cell damage and mental declines that are seen in normal aging.

Dementia can cause these symptoms:

  • Profound memory loss
  • Confusion
  • Poor judgment
  • Getting lost in familiar neighborhoods
  • Problems with speech, reading, writing, or understanding conversation
  • Using the wrong words for simple objects
  • Loss of interest in life or concern for other people

Dementia symptoms get worse over time. Cognitive changes like memory loss may be mild at first, but they usually worsen in just a few years.

People with MS often have cognitive symptoms during a disease flare, also called an exacerbation or relapse. In MS, cognitive changes tend to progress gradually and slowly. Once you have cognitive impairment, usually it doesn’t get much worse or cause dramatic changes in how you think, react, or function.

Dementia and MS may also cause similar mood problems, including depression and loneliness. People with MS who have cognitive impairment have high rates of depression.

Depression in MS may be strongly linked to difficulties with memory and thinking. In MS, brain lesions, especially in the temporal lobe, cause your cognitive and mood changes. People with MS who have lesions on their brain are more likely to have depression than those who have spinal cord lesions. Inflammation in the brain is a major cause of clinical depression and MS.

Depression and dementia may be linked by physical changes, too. In people with dementia, depression may be caused by changes in blood flow in your brain, brain atrophy, inflammation, nerve damage, and lesions called amyloid plaques that can build up in your brain. People diagnosed with depression earlier in life could be at twice the risk of having dementia later in life.

People with dementia and MS are more likely to slip and fall. Impaired vision, unsteady walking, slowed reaction time, and loss of balance are common symptoms of dementia and MS that make them more likely to slip, fall, and even hurt themselves.

People with dementia can get worse at walking as their cognitive functions decline. They may walk more slowly or haltingly. Often, they need more help from other people to get around.

Cognitive impairment in MS is one of many risk factors for falls, along with vision problems, a loss of balance called ataxia, fatigue, dizziness, as well as muscle spasms and weakness.

With MS, the risk of falling doesn’t necessarily go up as cognitive function goes down. People with MS who don’t use a mobility aid like a cane, walker, or scooter are more likely to fall. People with progressive forms of MS tend to have more falls, and these accidents may be a sign of their MS symptoms getting worse.

Falls may cause minor injuries like sprains, bumps, or bruises, but they can also cause serious head injuries or painful, debilitating fractures in people with either MS or dementia.

You may be able to manage mild cognitive impairment in MS with memory and thinking hacks: Give yourself enough time to do a task, repeat important information, make to-do lists, plan your activities so you don’t get confused by multiple tasks, and set reminders on your phone calendar. Newer, disease-modifying MS medications may improve cognitive impairment symptoms, too.

If you or your loved one has dementia, they may be able to slow down some cognitive declines with these steps:

  • Eat a healthy diet.
  • Stay physically active and engaged in social life.
  • Keep a positive outlook and attitude.
  • Avoid tobacco and alcohol.
  • Keep up with your medical care and vaccines to prevent infections.


Yes, it’s possible to have MS and the more severe dementia, such as Alzheimer’s disease. Changes to the brain can be caused by both MS and Alzheimer’s disease.

People with relapsing-remitting MS, primary progressive MS, secondary progressive MS, and even very mild MS can go on to develop Alzheimer’s disease too. One reason for this may be that treatment advances help all people with MS live longer. In older age, dementia is more common for everyone.

Severe cognitive changes in people with both dementia like Alzheimer’s and MS are probably due to their Alzheimer’s, but progressive MS could play a role too.

Because MS usually causes mild cognitive impairment, don’t assume you have early dementia if you have some memory losses or thinking changes. Talk with your doctor about tests you can take to measure your cognitive changes to screen you for early Alzheimer’s or other types of dementia.