In the United States, around 400,000 people suffer from multiple sclerosis, a neurological condition that commonly starts between age 20 and 40, according to the Merck Manual Home Edition. With multiple sclerosis, the patient's immune system attacks the central nervous system, which is comprised of the brain and spinal cord, resulting in damage to the myelin sheath, the covering of the neurons. The National Multiple Sclerosis Society noted that 50 percent of multiple sclerosis patients suffer from cognitive impairment, though only 5 to 10 percent of patients have severe enough cognitive problems that they affect normal functioning.
Multiple sclerosis patients can have different types of cognitive problems. Nicholas G. LaRocca, author of the chapter “Cognitive Impairment and Mood Disturbances” in the book Primer on Multiple Sclerosis noted that commonly affected cognitive functions in multiple sclerosis patients include learning, memory, complex attention, information processing speed, executive functions, visual-perceptual skills and word findings. Some cognitive functions are generally not affected in MS. These functions include reading comprehension, general intellect, conversational skills and basic attention. Cognitive problems can affect multiple sclerosis patients at any stage. For example, some patients may have trouble with memory at the onset of multiple sclerosis, though the National Multiple Sclerosis Society pointed out that these symptoms are more common in later stages of the disease.
Patients can develop cognitive problems from damage to the brain from the disease or as the result of the medication. The Cleveland Clinic lists cholesterol-lowering medications, muscle relaxants, anticholinergics, steroid medications, major tranquilizers, and some antidepressants and seizure medications as medications that may affect patients' thinking, and use of these drugs should be noted when assessing for cognitive problems. The type of cognitive impairment a patient has depends on where the lesions are in the brain.