Cognitive impairment due to multiple sclerosis: symptoms, characteristics and treatment

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

Let’s see in more detail what this disease is and the cognitive disorders it causes.

What is multiple sclerosis and how does it happen?

Multiple sclerosis is a disease of the central nervous system, autoimmune and chronic. It is one of the most common neurological disorders among the population between the ages of 20 and 30.

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

The immune defect that produces multiple sclerosis manifests itself with symptoms such as: fatigue, lack of balance, pain, visual and cognitive impairments, speech difficulties, tremors, Etc. In addition, cognitive disorders sometimes affect cognitive functions such as memory, language or executive functions.

The etiology of the disease is complex and is linked to different genetic and environmental factors, such as infection with the Epstein-Barr virus, tobacco, 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 person to person. and depending on the phenotype of the disease.

The following multiple sclerosis phenotypes have currently been described:

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

  • Sending recurrent multiple sclerosis: It is the most common form in the diagnosis of sclerosis. This phenotype is characterized by shoots interspersed with phases of remission, although its incidence decreases during the disease. Since patients do not fully recover, these episodes usually result in a cumulative increase in disability.

  • Secondary progressive multiple sclerosis (RME): This phenotype is the one that involves a greater degree of disability. It occurs in about a quarter of the patients with sclerosis in our country, and presents a slow neurological deterioration, with or without outbreaks. It is estimated that half of patients with this phenotype generally progress to this phenotype.

  • Primary progressive multiple sclerosis (PMPA): Patients with this multiple sclerosis phenotype have occasional periods of stability, with little transient improvement, without developing outbreaks.

Cognitive deficits in multiple sclerosis

Cognitive impairment in multiple sclerosis patients has a major impact on these people in activities of daily living. Here are the main cognitive areas affected by this disease.

1. Memory

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

Patients need more trials and repetitions to learn, although once they have learned information, performance in 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 changed almost from the start and indicate the onset of cognitive impairment.

Patients find it difficult to retain and manipulate information in working memory tests, as well as in tasks that require a certain speed of processing.

They also show difficulty following a conversation, reading or movie, as well as processing the information they have just seen, when activity has already changed.

3. Executive functions

Executive functions are impaired 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 find it difficult to plan trip details, manage resources or have a diary, for example. They also find it very difficult to anticipate events and change their strategy to provide solutions.

4. Language

Between 20 and 25% of patients see their tongue altered in multiple sclerosis. The main difficulty is observed in verbal fluency, the ability to produce spontaneous fluent speech. This alteration also affects the allocation of evocation memory, executive functions and processing speed.

Although the tongue is affected, aphasia is usually not too common in this disease.

5. Visuospatial functions

Visuospatial functions, responsible for representing, analyzing and mentally manipulating objects, Are affected in 10 to 20% of patients with multiple sclerosis. The patient has difficulty recognizing objects, such as faces, and performing visual and relational integration tasks and processing shapes.

Complications in the spatial calculation (depth perception) are also observed, which can pose problems for the driving of vehicles, due to the alteration of 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 patient functionality.

According to scientific studies, this type of cognitive intervention brings benefits to patients, with improvements in cognitive areas such as memory and the overall quality of life of those affected.

However, no definitive conclusion can be drawn about the effects of cognitive rehabilitation on the mood and quality of life of patients, due to the fact that different rehabilitation techniques have been used, there has been a lack of sensitivity in the measures used to evaluate the results. and small samples were used.

Regarding pharmacological treatment, several studies with stimulant drugs such as amantadine, l-amphetamine or modafinil, have not yet shown conclusive data as to their effectiveness, although they have been used in this type of treatment. disease.

Drugs used in Alzheimer’s disease, such as cholinesterase inhibitors, donezepil, rivastigmine or memantine, have not shown conclusive efficacy either.

Multiple sclerosis prevention: cognitive reserve

Cognitive reserve is our brain’s ability to compensate for impairment associated with aging or cognitive decline resulting from disease. This ability is largely determined by previously maintained brain activity, knowledge acquired, and good or bad habits adopted.

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

Daily practice stimulating activities that involve cognitive effort, such as reading, physical exercise or intellectual games, it appears to increase this cognitive reserve which may help patients with multiple sclerosis prevent future declines.

Bibliographical references:

  • Castro P, Aranguren A, Arteche I, 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.

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