Brain fog is one of several symptoms that is high on the list for many MSers. It is generally described as "mental cloudiness". Mental function is very poor. It is also referred to as cognitive dysfunction.
When you have this, several things can happen. You may feel confused. You may also be unusually forgetful. You can also have feelings of detachment and difficulty concentrating on things. If not treated, you may become more and more discouraged at not being able to complete your work. This in turn can lead to depression.
If you've ever been awakened from a deep sleep, you may have felt something similar. Sleep inertia or extreme grogginess feels very similar to this symptom, only it goes away after you completely wake up and get the cob webby feeling out of your head.
This particular symptom is not just something that people with multiple sclerosis experience. It can be caused by chronic fatigue syndrome, heavy metal poisoning (such as mercury poisoning), menopause, some sleep disorders, or hypothyroidism (or an under active thyroid gland).
These are not the only things that can cause brain fog. Environmental toxins, such as chemicals like pesticides, cleaning agents, and solvents can cause this symptom.
Certain prescription medications can also cause this symptom. If you need to take medications, be sure and check the side effects so that you know what to expect. If you take prescription or over-the-counter medications for things like allergies, pain, inflammation, high blood pressure, heart arrhythmias, glaucoma, infections, depression, or anxiety, one of these may be the cause. If the side effects become too much for you, ask your doctor if you might try something else.
Fatigue is said to be the number one physical cause of brain fog. If this is the case, then most MSers will probably experience it more often than not. Your brain needs a high amount of energy in to work best. When you are fatigued or tired, your brain may suffer and this symptom can set in.
Cir often complains of times when things are just not too clear (visually). When he feels like he's walking (or sitting) in the middle of a cloud. Or driving through a patch of fog.
He's not able to think clearly. And concentration is almost impossible. Detail work is best left till another time. He can sometimes play his bass guitar or drums, because these are things that use rote memory. In other words he sort of plays without thinking. He doesn't have to re-learn how to play them - he just plays.