Cognitive Impairment Due to Multiple Sclerosis: Symptoms and Treatment

Cognitive impairment due to multiple sclerosis It is present in 40 to 65% of people suffering from this disease and affects functions such as memory, language or executive functions.

Let's see in more detail what this disease consists of and the cognitive deterioration it causes.

What is multiple sclerosis and how does it occur?

Multiple sclerosis is a chronic autoimmune disease of the central nervous system.. It's one of the Neurological disorders more common among the population between 20 and 30 years.

This disease affects the myelin or white matter of the brain (substance that surrounds and insulates the nerves) and of the spinal cord, causing the appearance of sclerotic plaques that impair the normal functioning of these nerve fibers.

The immunological abnormality that causes multiple sclerosis manifests itself in symptoms such as: fatigue, poor balance, pain, visual and cognitive disturbances, speech difficulties, tremors, etc. In addition, sometimes there is a cognitive deterioration that affects cognitive functions such as memory, language or executive functions.

The etiology of the disease is complex and is related to different genetic and environmental, such as infection by the Epstein-Barr virus, smoking, vitamin D deficiency or ultraviolet light.

types of multiple sclerosis

The course of multiple sclerosis cannot be predicted, and the cognitive impairment it causes can vary from individual to individual. and depending on the phenotype of the disease.

Currently, the following multiple sclerosis phenotypes have been described:

• Isolated neurological syndrome: generally affects young individuals between the ages of 20 and 40. This is the first neurological clinical event suggestive of multiple sclerosis, lasting 24 hours. It can present a partial or total recovery, and it corresponds to a single lesion in the white matter of the brain.

• Relapsing-remitting multiple sclerosis: It is the most frequent form in the diagnosis of sclerosis. This phenotype is characterized by relapses interspersed with remission phases, although its incidence decreases during the disease. Because patients do not fully recover, these episodes often result in a cumulative increase in disability.

• Secondary Progressive Multiple Sclerosis (RRMS): This phenotype is the one that implies a greater degree of disability. It occurs in approximately a quarter of sclerosis patients in our country, and they present slow neurological deterioration, with or without flare-ups. It is estimated that half of the patients with this phenotype usually evolve to this phenotype.

• Primary Progressive Multiple Sclerosis (PPMS): Patients presenting this multiple sclerosis phenotype present periods of occasional stability, with temporary insignificant improvements, without developing flare-ups.

Cognitive deficits in multiple sclerosis

Cognitive impairment in patients with multiple sclerosis has a great impact for these people in the activities of daily living. The main cognitive domains affected in this disease are detailed below.

1. Memory

Memory is affected in 40 to 65% of patients. The main deficit is observed in the processes of acquisition, codification and learning of the information, which manifests itself, for example, when remembering names, conversations or arguments from books.

Patients need a greater number of trials and repetitions to learn, although once they have learned a piece of information, performance on recall and recognition tasks is similar to that of healthy subjects.

2. Attention and speed of information processing

These cognitive functions are affected in 20 to 25% of patients with multiple sclerosis.. They are altered practically from the beginning and indicate an incipient cognitive deterioration.

Patients have problems maintaining and manipulating information in tests of work memory, as well as in tasks that require a certain processing speed.

They also show difficulties to follow a conversation, a reading or a movie, as well as to process the information that they have just seen, when the activity has already changed.

3. Executive functions

Executive functions are altered in 15 to 20% of patients.. This impairment manifests itself in tasks that require abstract reasoning, planning, problem solving, or cognitive flexibility.

On a day-to-day basis, patients have difficulties when they need to plan the details of a trip, manage resources or keep an agenda, for example. They also have a lot of trouble anticipating events and changing strategies to come up with solutions.

4. Language

Between 20 and 25% of patients see their language altered in multiple sclerosis. The main difficulty is seen in verbal fluency, the ability to produce fluent spontaneous speech. This alteration also influences the affectation of recall memory, executive functions and processing speed.

Despite the fact that language is affected, aphasias are not usually very frequent in this disease.

5. Visuo-spatial functions

The visuo-spatial functions, responsible for representing, analyzing and mentally manipulating objects, are affected in 10 to 20% of patients with multiple sclerosis. The patient presents difficulties to recognize objects, such as faces, and to carry out visual relation and integration tasks and process shapes.

Complications are also observed in spatial calculation (depth perception), which can cause problems driving vehicles, due to the alteration in the perception of distances.

Treatment of cognitive impairment in multiple sclerosis

The usual non-pharmacological treatment in patients with multiple sclerosis usually includes cognitive rehabilitation, an intervention designed to improve cognitive functions, with the aim of improving the functionality of the patient.

According to scientific studies, this type of cognitive intervention brings benefits to patients, with improvements in cognitive domains such as memory and in people's general quality of life affected.

However, no definitive conclusions can be made about the effects of cognitive rehabilitation on patients' mood and quality of life, due to that different rehabilitation techniques have been used, there has been a lack of sensitivity in the measures used to assess results and samples have been used little.

Regarding pharmacological treatment, various studies with stimulant drugs such as amantadine, l-amphetamine or modafinil, have not yet shown conclusive data regarding its efficacy, despite the fact that they have been used in this type of diseases.

The drugs used in the Alzheimer disease, such as cholinesterase inhibitors, donezepil, rivastigmine or memantine, have also not shown conclusive efficacy.

Prevention in multiple sclerosis: cognitive reserve

The cognitive reserve It is the ability of our brain to compensate for deterioration related to aging or cognitive decline resulting from disease. This capacity is determined, to a large extent, by the brain activity previously maintained, the knowledge acquired and the good or bad habits adopted.

Recent research has confirmed that cognitive reserve in multiple sclerosis is a protective factor against long-term neurocognitive deterioration. This could modulate the severity of the symptoms of deterioration, modifying the clinical expression of the disease itself.

Practice daily stimulating activities that involve some cognitive effort, such as reading, physical exercise or playing intellectual games, appears to increase this cognitive reserve which may help multiple sclerosis patients prevent future declines.

Bibliographic references:

• Castro P, Aranguren A, Arteche E, Otano M. Cognitive impairment in multiple sclerosis. An Sis Sanit Navar 2002; 25: 167-78.

• Olascoaga J. Quality of life in multiple sclerosis. Rev Neurol 2010; 51: 279-88.