Multiple Sclerosis and Memory: Thinking Problems in MS

Many people with multiple sclerosis notice changes in memory, focus or thinking speed. Here's how common it is, which kinds of memory MS tends to affect, how it differs from dementia, and practical ways to cope.

By Jim Pavlish, Editor · Last updated: October 30, 2026 · Editorial policy

Short answer: yes, multiple sclerosis can affect memory and thinking. The MS Society (UK) says 4 to 7 in every 10 people with MS have some change, usually mild to moderate: slower thinking, trouble learning new information and remembering to do things. It's different from dementia; most people keep their long-term memories and everyday skills. Tell your MS team about any changes.

"I lose the thread when someone interrupts me." "Names just won't stick anymore." "I can still do it, it just takes me twice as long." People with multiple sclerosis (MS) often describe changes like these. Some call it "brain fog" or "cog fog."

If you or someone you love has MS and is noticing memory or thinking changes, you're not imagining it, and you're not alone. This page is general information, not medical advice. Tell your doctor or MS team about any changes you notice.

How common are thinking problems in MS?

MS is a condition in which the immune system damages the protective coating around nerves in the brain and spinal cord. Remembering, concentrating and thinking all depend on messages traveling along those nerves, so damage can slow or interrupt them.

The MS Society (UK) says somewhere between 4 and 7 in every 10 people with MS will have some kind of change in memory or thinking. The US Department of Veterans Affairs' MS Centers of Excellence give a similar range, about 40 to 66 percent over the course of the disease. Both stress that for most people the changes are mild to moderate, not severe, and that not everyone with MS has them.

These are sometimes called "invisible symptoms" because other people may not notice them, even when they make work and daily life harder.

Which thinking skills does MS tend to affect?

A 2020 review in The Lancet Neurology found that processing speed (how quickly you take in and respond to information) and episodic memory (memory for events and new information) are the thinking skills most often affected in MS.

According to the MS Society, common difficulties include:

• Remembering to do things, like sending a birthday card on time or replying to an email (called prospective memory)
• Recall, especially of recent things such as new people's names, shopping lists or whether you've taken your medicine
• Attention and multitasking, such as following a conversation while the TV is on, or picking up where you left off after an interruption
• Thinking speed, so tasks take longer even though you can still finish them
• Planning and problem-solving, like knowing where to start on a task
• Finding the right word, the "tip of the tongue" feeling

The VA notes that the most common memory issue in MS is learning new information. People may need more time or more repetitions to take something in, but once it's stored, they can usually recall it well.

How MS memory problems differ from dementia

This is often the biggest worry, so it's worth saying plainly. The MS Society says people with MS memory problems usually still know who they are, have no major trouble talking or reading, and can carry out daily activities. Recognizing familiar things, remembering long-practiced skills like tying shoelaces, and general knowledge are rarely affected. The VA adds that general intelligence is usually not affected by MS.

Some people with MS do eventually develop more severe cognitive problems, but most don't. The MS Society says thinking problems don't always get worse: for some people they get worse, for some they stay about the same, and for others they improve.

If memory changes are new, getting worse quickly, or affecting safety, talk to the doctor. They can look for other causes, too. For more on dementia itself, see What Is Dementia?.

Things that can make it worse

The MS Society lists several things besides MS damage that can affect memory and thinking. Many of them can be treated or improved:

• Fatigue and pain, which make it harder to focus
• Low mood, anxiety or depression (see Depression and Memory ("Pseudodementia"))
• Being too hot or too cold
• Poor sleep and stress
• Infections and other illnesses
• Medicines that affect the nervous system, such as some sleeping pills and painkillers, or taking five or more medicines regularly
• Dehydration, poor diet, drinking too much alcohol, and inactivity

This is one reason to raise thinking changes with your MS team: sometimes the fix is treating sleep, mood or fatigue. If you think a medicine may be playing a part, ask your doctor or pharmacist. Don't stop or change any medicine on your own.

Getting checked and getting help

The MS Society suggests regular cognitive assessments, for example every year or two, to keep an eye on changes and find new strategies. The Lancet Neurology review notes that a short test called the Symbol Digit Modalities Test, which measures processing speed, is quick and reliable enough to use routinely in clinics. The same review says there is growing evidence that processing speed and memory can respond to cognitive training.

Your doctor may refer you to a neuropsychologist, occupational therapist or speech and language therapist for a fuller assessment and practical strategies. The National MS Society also describes cognitive rehabilitation as one option.

Everyday strategies that help

These tips come from the MS Society, the National MS Society and the VA:

• Write it down right away. Keep a notebook or use your phone as soon as you learn something important.
• Use one calendar or planner for appointments and tasks, plus phone alarms for reminders. See Memory Aids and Tools.
• Give things a home. Keep keys, glasses and your phone in the same spot every time.
• Do one thing at a time. Turn off the TV or radio when you need to focus. See Focus, Attention and Multitasking.
• Use visual reminders, like leaving an item in an obvious place to remind you of a task in progress.
• Plan demanding tasks for your best time of day and take breaks before fatigue builds.
• Allow extra time and let people know you may need a moment to find a word or think something through.
• Stay active, sleep well and keep your mind engaged. The MS Society notes that a mentally active lifestyle ("cognitive reserve") seems to offer some protection. See Cognitive Reserve.

Common questions

Can MS cause memory loss?

Yes, MS can affect memory, most often learning and recalling recent information and remembering to do things. The MS Society says recognition, long-practiced skills and memories of the past are rarely affected, and most people's changes are mild to moderate.

Is MS brain fog the same as dementia?

No. Most people with MS memory problems still know who they are, can talk and read without major difficulty, and manage daily activities. A small number of people develop more severe problems, so it's important to tell your MS team about any changes.

Do MS thinking problems always get worse?

No. The MS Society says that for some people they get worse, for some they stay about the same, and for others they improve. Regular assessments, for example every year or two, help track changes.

What can I do about MS memory problems?

Talk to your doctor or MS team, who can check for treatable factors like poor sleep, low mood, fatigue or medicine side effects and refer you for assessment or cognitive rehabilitation. Everyday strategies such as writing things down, using reminders and doing one thing at a time also help.

The bottom line

Memory and thinking changes are common in MS, but for most people they are mild to moderate and very different from dementia. Slower thinking and trouble learning new information are the most typical problems. Tell your MS team about any changes, ask about regular check-ups of your thinking skills, and lean on simple tools like notes, reminders and routines.

Sources

1. MS Society (UK): Memory and thinking
2. National MS Society: Cognitive Changes
3. US Department of Veterans Affairs, MS Centers of Excellence: Cognitive Changes and Multiple Sclerosis
4. Lancet Neurology (2020): Benedict RHB et al., Cognitive impairment in multiple sclerosis: clinical management, MRI, and therapeutic avenues

Not medical advice. This article is general information, not a diagnosis or treatment plan for any individual. Talk with a doctor about your situation.

Related articles

• Brain Fog: Causes and Fixes
• White Matter Disease on a Brain Scan: What It Means
• Working Memory
• Memory Aids and Tools
• Focus, Attention and Multitasking
• Depression and Memory ("Pseudodementia")