Brain Fog in LEMS

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by Mary Chapman |

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brain fog and LEMS

While it’s not a classic symptom, some people with Lambert-Eaton myasthenic syndrome (LEMS) report experiencing brain fog, or difficulties with thinking, remembering and processing information, affecting both their personal and professional life.

What is LEMS?

LEMS is a rare autoimmune disease that mainly affects muscles in the lower limbs. People with the disease typically experience muscle stiffness, fatigue, pain and cramps, drooping eyelids, and problems with swallowing or speaking. Anxiety and depression can also be common.

What is brain fog?

Brain fog is not a medical condition, but a term given to problems with focus and concentration, and memory loss. All of these can affect patients’ quality of life.

Episodes of brain fog can leave a person unable to think clearly for hours or even days. Those who experience it often complain of an inability to perform day-to-day tasks, organize their thoughts, or hold a conversation. Some people have problems with word choice and language, and their speech might be slow and confused.

While problems with cognitive processes are not due to lower intellect, they can be perplexing and disturbing to those who experience them. Brain fog can affect your confidence and self-esteem.

How is brain fog linked to LEMS?

Secondary dysautonomia, which can cause brain fog, can occur in LEMS.  Dysautonomia is a general term for a group of disorders marked by problems with the working of the autonomic nervous system (ANS). The ANS is the part of the nervous system that controls involuntary body functions such as heart rate, blood pressure, breathing, and digestion. Autonomic dysfunction occurs in 80% to 96% of LEMS patients.

When it’s associated with lung cancer, LEMS is a type of paraneoplastic syndrome of the nervous system due to cancer treatments. Among its symptoms are memory loss and other cognitive difficulties.

What makes brain fog worse?

Just as excessive physical activity will result in muscle fatigue, difficult or protracted mental work — especially under conditions of stress or a lack of sleep — can cause or aggravate brain fog and related cognitive problems.

A person’s general health can also affect the severity of brain fog, particularly depression or anxiety.

How do doctors treat brain fog?

You may find the best way to manage brain fog, and feelings of being “out of it,” is to balance activity with rest to avoid becoming overwhelmed. To pace yourself, find a comfortable baseline of mental activity, and divide it into small manageable portions that are interspersed with periods of rest or relaxation. Stop cognitively demanding activities before you reach “mental fatigue.” Try not to push yourself past limitations you have set for yourself.

If you experience short-term memory loss, it might be helpful to keep lists of important things you need to do for each day. Also make sure you return items, such as keys or medication, to their proper place after use. Instead of multitasking, focus on one activity at a time.

It is very important that you have proper support. If you’re having a tough time coping with brain fog, you may want to discuss psychological remedies with your physician. Be sure to also let close family members, and trusted friends and co-workers know of the trouble you’re having, as their awareness can help you to cope.


Last updated: Oct. 26, 2020


Lambert-Eaton News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.