Cognitive functions of the brain: the structure of cognition. Cognitive disorders in general clinical practice Human cognitive functions

Cognitive disorders of brain function are specific deviations that lead to personality disorder because they interfere with cognitive activity person. They occur in adults and children. How does cognitive dysfunction occur, for what reasons and how to recognize it? Let's try to figure it out.

What are cognitive impairments, their types and mechanism of development

What are cognitive impairments? These are deviations in normal operation and brain function. They arise from various reasons in adults, can also appear in children. The human brain is a complex mechanism that regulates all physiological and mental processes in the body. Cognitive or cognitive functions include:

Any violation of them can provoke a change in personality and turn a rational person into an animal that is guided only by instincts. How do such disorders develop? First of all, this is due to a disruption in the connection between the cerebral cortex and subcortical structures. Depending on the location of the damage, the following disorders are distinguished:

Depending on the degree of damage, the following cognitive disorders are distinguished:

Brain activity is very complex mechanism. Any violation of it contributes to the emergence of deviations that significantly affect human behavior.

Causes of development, main symptoms

Why do cognitive impairments occur in children and adults? Depending on their nature of origin, they are distinguished:

• functional (temporary);
• organic (associated with the occurrence of an irreversible pathological process).

Functional disorders are predominantly temporary. They are often associated with the following phenomena:

Such abnormalities in brain activity can occur at any age. For example, cognitive impairment in children can be triggered by an unfavorable environment at home or at school, the death or illness of friends, close relatives, and other emotional shocks. They are temporary and go away on their own when the irritating factors disappear.

Organic disorders are associated with pathological processes in the brain region. There are several reasons for this condition:

How to identify signs of cognitive impairment in the early stages in order to begin appropriate treatment in time? You should pay attention to the following symptoms:

• deterioration of memory and ability to memorize;
• decreased attention;
• fatigue from the simplest mental (intellectual) activity.

If such disorders are present (especially in children), it is necessary to undergo an examination so as not to start the disease and begin treatment on time.

In more severe cases (at a moderate stage), the following symptoms are observed:

In the most last stage, which is called dementia, the following unpleasant symptoms are added to the above:

• personality disorder;
• inability to perform basic self-care functions (for example, inability to go to the toilet, wash, eat);
• change in character;
• mental deviations (a person forgets who he is, does not recognize people around him).

The earlier cognitive impairment is identified, the better it can be treated with medications and psychological techniques. Dementia is progressive and cannot be cured.

Diagnosis, treatment and prevention methods

How to determine if a person has cognitive impairment? To do this, the patient must undergo a special examination, which includes the following procedures:

Only after identifying the cause of deviations is it prescribed necessary treatment. It is based on the use of medications. So persistent brain damage in dementia is treated with the following medications:

1. Donepezil.
2. Galantamine.
3. Rivastigmine.
4. Memantine.
5. Nicergoline.

They are prescribed only by a doctor. He also determines the dosage and duration of therapy. For minor impairments of cognitive functions, medications are used that help improve blood circulation, as well as neuroprotectors. These are the following drugs:

Except medicines a special anti-cholesterol diet is prescribed to improve blood flow and oxygen supply to the brain. It consists of refusing fatty varieties meat, dairy products and consumption fresh vegetables and fruits, seafood. It is also important to take B vitamins, exclude them from the diet alcoholic drinks, coffee.

Once cognitive impairment occurs, it is rarely possible to cure it completely. You can only pause the process.

To do this you need to change your way of life. Therefore, to suspend negative phenomena in the brain one should adhere to the following rules:

If you stick to the right image life, then brain abnormalities will not occur very soon. This is important for maintaining a person’s well-being and intellectual activity.

Cognitive impairment can appear at any age for one reason or another. They can cause a person and his loved ones a lot of trouble, as they lead to personality disorder and slow degradation. If such deviations are detected, it is important to consult a doctor for help as soon as possible in order to prevent complications.

Man differs from animals in the presence of higher nervous activity. The ability to think, communicate using meaningful speech, express it in writing, as well as perform directed actions, plan and holistically perceive reality are combined into cognitive functions.

What do cognitive functions include?

Cognitive or cognitive functions are those brain processes that are aimed at interacting with other people and the world around us. Human life is extremely dependent on the ability to remember and store information, correctly compare known facts, and anticipate the consequences of one’s actions. The degree of development of such mental processes is individual; they can be trained, but can be disrupted under the influence of various factors.

It is a mistake to believe that cognitive functions are only memory (see). The ability to perceive, store and reproduce information is important, but it is impossible without other processes.

Attention is one of these functions, which is characterized by the ability to concentrate mental processes on a specific object. Each individual has the following characteristics:

• sustainability;
• switchability;
• concentration;
• concentration;
• volume.

The function of perception is the construction of integral images based on information received from the senses. Perception is characterized by constancy: an object is defined as the same regardless of changing external conditions. This ability is not typical for animals: a dog may consider a familiar person a stranger if he is in the shadows or wears unfamiliar clothes.

Find out why this happens with age: causes.

Cognitive abilities include praxis - the ability to produce a conscious sequence of actions or movements. The ability begins to be mastered as early as infancy when a rattle is placed in a child’s hand for the first time. Then finger praxis develops - the ability to manipulate one’s fingers, and gestures appear.

A special place is occupied by symbolic praxis - these are various gestures by which one can understand what a person wants to say, imitation of holding a telephone receiver, driving a car, drinking from a glass. The language of the deaf is roughly based on this principle: performing a special set of gestures allows you to communicate without words.

Connection of functions with parts of the brain

What are cognitive functions based on their location in the brain? They are represented as special areas of the brain with groups of neurons responsible for certain type nerve transmission. Impaired blood supply, damage or tumor growths in these areas lead to impairment of the cognitive functions of the brain.

Cognitive functions are formed in the cortex. It is divided into three zones:

• sensory – involved in processing signals from the senses;
• motor – provides movement different parts bodies;
• associative – provides a connection between the two previous ones, determines a behavioral reaction based on impulses from the sensory zone.

The frontal lobes of the cortex provide logical, speech, and movement planning. The centers for analyzing sensory sensations are located in the parietal region. The processing of data from the visual analyzer is carried out by the occipital lobe, and the auditory lobe in the temporal lobe.

More ancient parts of the brain provide basic survival skills. The limbic system is memory, smell, emotions. The thalamus is responsible for redirecting impulses from the organs of hearing, vision, balance and tactile sense. Memorizing new information occurs thanks to the hippocampus.

The midbrain plays a role in consciousness and self-awareness, feelings of existence, and adaptive behavior. The interaction of all departments and the transmission of impulses occurs thanks to neurotransmitters:

• serotonin;
• dopamine;
• GABA;
• adrenalin;
• acetylcholine.

It often happens that they slow down or speed up cognitive tasks.

Reasons for violation

The severity of the disorders can vary: from mild to severe. Factors influencing the development of pathology are:

1. Degenerative diseases: , Parkinson's.
2. Pathologies associated with blood vessels: heart attack and stroke, atherosclerosis.
3. Metabolic disorders: hypoglycemia, hepatic or renal encephalopathy, drug use (benzodiazepines, anticholinergics), hypo- or hyperthyroidism.
4. Neuroinfections.
5. Head injuries.
6. Brain tumors.
7. Pathology of cerebrospinal fluid outflow.

The type of violation will depend on the location of the damaging factor. Mild or cognitive impairment moderate severity Even after a stroke, older people can recover with proper treatment.

Cognitive functions include the most complex processes controlled by the brain.
These are memory, speech, intelligence, praxis (performing purposeful actions)and gnosis (holistic perception of reality).

With their help, knowledge of the surrounding world is accomplished and purposeful interaction with it is ensured.

Thanks to cognitive functions, information is perceived, processed and analyzed, memorized, stored,constant exchange between individual parts of the brain, development of a specific program of action, its implementation and monitoring of results.

Sometimes, under certain circumstances, more often - in case of any diseases or traumatic injuries brain, there may be a deterioration in cognitive performance compared to the individual baseline level.

This occurs due to a decrease in one or more of its components (memory, praxis, gnosis, speech).

If cognitive decline is due to cerebrovascular disease ( discirculatory encephalopathy, stroke ), then the obstructed functioning of higher cortical functions is called vascular cognitive disorders.

The location and extent of brain damage determine the severity and nature of cognitive decline.
Dysfunction of the white matter of the frontal lobes, which contains the processes of neurons, leads to a decrease in cortical afferentation. As a result, the number of nerve impulses reaching the frontal cortex decreases, which means it receives less information.

If the deep parts of the brain (both gray and white matter) are affected, secondary dysfunction of its anterior parts occurs.

Due to the fact that cognition is ensured by the coordinated activity of the entire brain at the same time, it does not have strict local connections with specific brain structures.

But different parts of the brain are not equal participants in this process. Each structural unit the brain makes its own individual contribution, depending on the role it plays.

Accordingly, the brain is divided into
three large functional blocks.

1. First - neurodynamic - consists of the ascending part of the reticular formation, nonspecific nuclei of the thalamus and limbic system. These brain formations are considered structures of the first level of cognitive function.
They provide the brain with an optimal level of wakefulness, promote concentration and stability of attention, and create motivational and emotional accompaniment of higher brain activity.

2. Second functional block - secondary and tertiary zones of the cortical analyzers of hearing, vision, sensitivity. These include the temporal, parietal and occipital lobes of the brain. These areas of the brain receive and process various information.

3. Third , the highest functional level is formed by the premotor and prefrontal cortex. They are located in the frontal lobes,regulate voluntary human activity, are responsible, on the basis of the information received, for determining and setting goals, plan actions, carry them out and monitor the results obtained.

Therefore, damage to any of the listed anatomy - functional levels, leads to disruption of certain - or several or all cognitive processes.

Our brain has multimillion-dollar interneuron connections, it resembles a huge labyrinth, has a large neuroplasticity . Connections between neurons form and change throughout life. Due to the multimillion-dollar and billion-dollar connections between various neurons and their groups, cognitive functions exist.

The formation of long-term memories and the brain's ability to retrieve life experiences from them occurs throughout life. The hippocampus is responsible for storing long-term memories. The more connections there are between neurons in the brain, the smarter and more experienced the brain is.

Higher brain activity can be divided into functions:

• general functions, which cannot be localized in one specific area of ​​the brain, but require the joint work of several areas:

• attention and ability to concentrate
• memory
• higher order executive functions
• social and personal behavior.

• localized functions, which are associated with the normal structure and functioning of a specific part of one hemisphere (Fig. 1).

Rice. 1. Localization of functions in the brain

Cognitive functions

Attention and concentration

Anatomy

Maintaining attention is ensured by the same anatomical substrate as consciousness, namely, the activating reticular system, which projects to the thalamus and further to the cerebral cortex.

Survey

Clinical tests for studying attention and concentration include assessment of the following functions:

• Orientation in space and time. - Can the patient name the time of day, day of the week, month and year, the place in which he is located?
• Repetition number series in forward and reverse order.
• Serial account— sequential subtraction of 7 from 100; if the attempt fails, count down from 20 or call the months in reverse order.

Clinical manifestations

Delirium(previously considered as acute confusion) is a syndrome manifested by weakening of attention and ability to concentrate. A fairly common disorder, especially among patients in older age groups. Other manifestations of this condition

• confusion of thinking and speech
• visual hallucinations
• disruption of the sleep-wake cycle: the patient remains awake for a long time and is more restless at night
• memory impairment - inability to learn new information
• unmotivated changes in mood - the patient can be excited, energetic or, conversely, depressed and apathetic.

As one might assume based on anatomy, the causes of delirium are the same as in the case of altered consciousness. This can be regarded as a relatively favorable outcome comatose states. Depending on the cause, delirium usually goes away within a few days.

Memory

Definitions

As established by neuropsychological research, the memory system includes several components.

• Nonspecific memory- mastering motor actions performed automatically (for example, driving a car).
• Specific memory accessible to consciousness and includes:

• episodic memory- recalling autobiographical details and other experienced events corresponding to a certain period of time
• semantic memory— storage of general knowledge about the world around us.

Other important components of memory:

• Short-term memory- working memory, responsible for the immediate recall of small amounts of verbal or spatial information.
• Anterograde memory- learning new material.
• Retrograde memory- reproduction of previously learned material.

Anatomy

The anatomical basis of episodic memory is limbic system(includes the hippocampus, thalamus and their connections), while semantic memory is associated primarily with temporal cortex . The nonspecific memory system includes basal ganglia, cerebellum and their connections with the cerebral cortex.

Survey

Memory assessment tests:

• Reproduction of complex verbal information (naming a name and address at intervals of 5-10 minutes, an arbitrary set of words, retelling short story) and a set of geometric figures for the purpose of studying verbal and non-verbal anterograde memory
• Recalling Autobiographical Information to Assess Retrograde Memory
• General knowledge and vocabulary tests to assess semantic memory, such as enumeration latest news, names politicians and other world celebrities.

Clinical aspects

Amnesia can be acute, transient and permanent. It can develop relatively in isolation or in combination with other cognitive disorders.

Transient global amnesia (TGA) characterized by complete loss of both retrograde and anterograde memory; observed in middle-aged and older people. Retrograde amnesia can last for months or even years. The patient appears confused and constantly asks simple questions, such as “What happened?”, but there are no disturbances of consciousness or cognitive deficits. The attack, including retrograde amnesia, lasts for several hours, so that memory loss lasts only during the attack. Relapse is rare and the prognosis is favorable. Previously, TGA was considered a manifestation of cerebrovascular pathology; in many patients its cause remains unclear, although it is often associated with migraine.

Some patients with repeated episodes of TGA have frontal lobe epilepsy- “transient epileptic amnesia.”

Amnestic syndrome manifests itself as persistent memory loss (anterograde and retrograde), often irreversibly, in most cases occurring together with other cognitive impairments. The cause is a focal lesion of the limbic system, for example, ischemia of the hippocampus, its damage due to encephalitis caused by the herpes simplex virus, infarction in the thalamus, vitamin B1 deficiency (Korsakoff syndrome), closed severe traumatic brain injury. Severe amnesia may occur early sign Alzheimer's disease.

Amnesia, along with other cognitive disorders, occurs suddenly and is reversible with acute conditions confusion, however, is persistent (like other disorders) with the development of dementia (see below).

Executive functions, personality and behavior

It is difficult to clearly define the concept of executive functions, which include the ability to plan, adapt, operate with abstract concepts and solve problems associated with various personality traits and social behaviors, such as initiative, motivation, or inhibition.

Anatomy

The frontal lobes of the cerebral hemispheres, especially prefrontal gyri, play key role in the formation of normal executive functions, while the ventromedial parts of the frontal lobes are responsible for social awareness, personality and behavior.

Survey

Tests to detect frontal lobe dysfunction are indicative and therefore important information can be gleaned from stories from loved ones (Can the patient cope with work? Does he go to the store on his own?) and clinical examination.

Patients with bilateral frontal lobe disease perform poorly on the following tests:

• broken fluency of speech; for example, when asked to list products purchased in a store; when naming words starting with a specific letter
• interpretation of sayings; for example, the correct interpretation of the meaning of sayings and proverbs is violated
• conscious assessment; for example, the inability to estimate the height of a famous building.

Perseveration is also a sign of damage to the frontal lobes; consists of obsessive repetition of certain words or movements.

With more severe damage to the frontal lobes, loss develops inhibitory control: the patient becomes irritable, aggressive with deviations in social behavior and hygiene, characterized by untidiness in urine and feces. Some patients become unmotivatedly cheerful and noisy, but others, on the contrary, are passive, taciturn and inactive. If these symptoms are extreme, the condition may be akinetic mutism.

Loss of normal inhibition may cause primitive reflexes, of which the most important are the following:

• prehensile- involuntary grasping that occurs when a light blow is struck on the patient’s palm. Most pronounced when the patient's attention is distracted
• sucking- caused by a jerky touch of a spatula or a neurological hammer to the patient’s lips; in the case of a positive reflex, the lips are pulled forward.

Clinical manifestations

Bilateral frontal lobe lesions may be caused by trauma, tumor, infarction, or focal degenerative lesions.

Localized cognitive functions

Hemispheric dominance

For most people left hemisphere the brain is responsible for speech functions. Even for most left-handers, the left hemisphere is dominant.

Functions of the dominant hemisphere

Speech

Definitions

Aphasia, or dysphasia, - violation speech functions as a result of focal brain damage. There are problems with pronunciation, reading and writing, which can occur independently of each other ( alexia/dyslexia And agraphia/dysgraphia respectively).

Dysphasia should be distinguished from dysarthria- articulation disorders due to damage to the muscles involved in pronunciation or the cranial nerves innervating them (including damage to the lower (bulbar) parts of the brain stem), cerebellum, basal ganglia, cerebral hemispheres. Mutism— complete absence speech production may be a consequence of a severe form of aphasia or dysarthria (anarthria) or a manifestation of mental illness.

Survey

Clinical tests for speech impairment are performed.

• Smoothness of speech; the patient can spontaneously (with a free story) pronounce phrases of normal length (five or more words). When fluency of speech is impaired, syntax errors
• Speech understanding; it is necessary to assess whether the patient can point to an object used in everyday activities (pen, watch, keys) when calling them a doctor. Can he perform more complex tasks (“Take the keys and pass me the pen”)? Can I answer specific questions(“What is the name gray dust, which remains after smoking a cigarette?”)?
• Repetition; whether the patient can repeat individual words or sentences
• Naming everyday items: a watch or a fountain pen, as well as less common ones - a pen, a buckle, an adjustable wrench. The function of naming objects is impaired to a certain extent in the majority of patients with aphasia ( anomie).

In addition to the above tests, writing and reading abilities can be assessed separately.

Clinical anatomy

Using these tests, it is possible to more accurately determine the degree of dysphasia a patient has (Fig. 2). The causes of focal lesions in the areas responsible for speech functions can be trauma, heart attack or tumor. Degenerative brain diseases (such as dementia, see below) are less likely to be the cause of these disorders.

Rice. 2. Topical diagnosis and classification of dysphasia syndrome. The location of the lesion anterior to line a causes dysphasia with impaired speech fluency. With a more dorsal localization of the lesion, fluency of speech is preserved. If affected in the area below the line b, passing through the Sylvian fissure, the understanding of addressed speech suffers, while when the focus is located higher, it is preserved. Damage to the area enclosed by the line With, affects the patient's ability to repeat phrases, whereas if affected outside this area, this ability is preserved. Thus, speech in Broca's aphasia (area B) is intermittent, its smoothness is lost, repetition is impaired, but understanding is preserved. The topical characteristics indicated in the diagram are fully valid for the occurrence of conduction aphasia (area C) and Wernicke's aphasia (W). With the development of global aphasia, all speech functions suffer

The ability to write is associated with the area of ​​the angular gyrus, which is located anterior to the speech zone. Lesions in this area in combination with a writing disorder (agraphia or dysgraphia) in typical cases lead to disorders such as acalculia or dyscalculia - an impairment in the ability to understand numbers, write them, and hence, counting disorders.

Praxis

Dyspraxia (apraxia)- inability to perform complex motor actions, not associated with a decrease in muscle strength, sensitivity and coordination. It may be detected when the patient performs tests to repeat gestures or imitate the use of household objects, such as a hammer or scissors. The cause of dyspraxia may be damage to the parietal region of the dominant hemisphere. The pathways that provide praxis originate in the parietal region and go to the premotor region of the frontal lobe of the same and contralateral hemispheres, passing to the opposite side through the corpus callosum.

Functions of the subdominant hemisphere

Due to the fact that most of the areas responsible for speech functions are located in the dominant hemisphere of the brain, the subdominant hemisphere in to a greater extent(although not exclusively) responsible for visuospatial functions.

Ignoring

Patients with acute extensive damage subdominant (usually right) hemisphere, such as those with a stroke, may behave as if left half space ceased to exist. This can apply both to the left side of the patient's body and to the outside world. The patient experiences:

• denial of the inability of the left side of the body, despite its paralysis due to a stroke
• complaints that left hand belongs to someone else
• ignoring visual and tactile stimuli on the left side
• dressing only right side, eating only on the right side of the plate.

Ignoring can be established through tests in which the patient is asked to redraw a simple drawing of a house or a clock dial. Ignoring the left side of the picture is a sign of damage to the subdominant hemisphere. More subtle disorders can be detected by tests such as strike-out given letters on a page of text or an attempt to bisect a horizontal line (a patient with neglect will certainly bisect the line to the right of the center point).

Ideas about the mechanisms underlying ignoring are contradictory; this phenomenon remains poorly studied. Although many stroke patients recover from neglect, for a significant number of patients this problem remains and significantly limits the ability to carry out rehabilitation measures.

Apraxia of dressing

Patients with damage to the subdominant (right) hemisphere of the brain very often cannot dress themselves correctly. The term “apraxia” in this situation is not entirely correct to use, since the disorder has not so much a motor as a visual-spatial basis due to the fact that patients are not able to correctly orient parts of their body for dressing.

Constructive apraxia

A patient with a lesion of the subdominant hemisphere is usually unable to create complex shapes from several elements, such as a star, cube, or overlapping polygons. Again, the term “apraxia” is not entirely correct here, since the patient has predominantly visuospatial disorders rather than motor ones.

Agnosia

More complex visual-perceptual disorder. Usually occurs with bilateral parieto-occipito-temporal lesions and includes:

• inability to recognize objects presented visually ( visual agnosia - visual agnosia). The diagnosis can be established if dysphasia, damage to the eye itself and intellectual decline are excluded
• inability to recognize familiar faces ( prosopagnosia)
• central color vision disorders.

Dementia

Dementia is a global acquired disorder intellectual abilities, usually progressive and occurring in a state of maintained level of wakefulness. The patient with dementia has impairment in two or more cognitive functions (one of which is memory, and the other may include impairments in language, praxis, visuospatial gnosis, personality and social behavior, and abstract thinking) in the absence of depression and mental disorders, such as depression and schizophrenia, the manifestations of which may be similar to those of dementia.

Cortical and subcortical dementia

It is useful to distinguish dementia with predominant damage to either the cerebral cortex or subcortical structures (some types of dementia have mixed character). When the cortex is damaged, the patient experiences impairment of speech functions, memory, praxis and/or visuospatial gnosis. Subcortical dementias are characterized to a greater extent by a slowdown in cognitive functions and thinking ( bradyphrenia), personality and mood disorders. Patients become apathetic and inert, with signs frontal lesion. The functions of memory, speech, praxis and gnosis may remain relatively intact, according to at least in the early stages of the disease.

Neuropsychological examination

Cognitive function can be assessed during a clinical examination. In addition, there are standard scales and questionnaires; one of the most used - Mini Mental Status Rating Scale(Mini-Mental State Examination, MMSE) (Table 1). A score of less than 24 (out of a possible 30) is a sign of dementia. However, the total score based on the results of using this scale is insensitive to early stages dementia, in particular in patients with high premorbid intellectual level, in cases with limited cognitive deficits, for example, with damage to the subdominant hemisphere or frontal lobes. Many patients with cognitive deficits require in-depth psychometric evaluation with the participation of a psychologist.

Table 1. Mini-Mental State Examination (MMSE)

Sign	Sum of points
Orientation
Year, month, day, date, season
State, city, street, hospital, ward
Naming objects
The doctor names three objects and asks the patient to repeat them (then repeat the same three objects three times)
Attention
Serial counting by 7 (5 numbers in total); Each correct answer is worth 1 point
Memorization
The subject is asked to remember the three words that he repeated earlier
Speech
Ask the subject to name a pen and a watch
Repeat the phrase: “If and or no but”
Completing a three-step task: (each step is worth 1 point): take a sheet of paper right hand, fold it in half and place it on the table
Follow the command written on paper: “Close your eyes”
Write a phrase, note whether it has a subject and predicate
Copy
Copy two overlapping pentagons
Total amount points

Neurology for doctors general practice. L. Ginsberg

Cognitive functions of the brain are the ability to understand, cognize, study, realize, perceive and process (memorize, transmit, use) external information. This is a function of the central nervous system– highest nervous activity, without which a person’s personality is lost.

Gnosis is the perception of information and its processing, mnestic functions are memory, praxis and speech are the transfer of information. When these mnestic-intellectual functions decrease (taking into account the initial level), they speak of cognitive impairment, cognitive deficit.

Decreased cognitive function is possible in neurodegenerative diseases, vascular diseases, neuroinfections, severe traumatic brain injuries. In the mechanism of development, the main role is played by mechanisms that separate connections between the cerebral cortex and subcortical structures.

The main risk factor is considered arterial hypertension, which triggers the mechanisms of vascular trophic disorders and atherosclerosis. Episodes of acute circulatory disorders (strokes, transient ischemic attacks, cerebral crises) contribute to the development of cognitive disorders.

There is a disruption of neurotransmitter systems: degeneration of dopaminergic neurons with a decrease in the content of dopamine and its metabolites, the activity of noradrenergic neurons decreases, and the process of excitotoxicity is launched, that is, the death of neurons as a result of disruption of neurotransmitter relationships. The magnitude of the damage and the localization of the pathological process matter.

Thus, with damage to the left hemisphere, it is possible to develop apraxia, aphasia, agraphia (inability to write), acalculia (inability to count), alexia (inability to read), letter agnosia (failure to recognize letters), logic and analysis, mathematical abilities are impaired, voluntary mental activity is suppressed .

Damage to the right hemisphere is manifested visually - by spatial disturbances, the inability to consider the situation as a whole, the body diagram, spatial orientation, emotional coloring of events, the ability to fantasize, dream, and compose are disrupted.

The frontal lobes of the brain play an important role in almost all cognitive processes - memory, attention, will, expressive speech, abstract thinking, planning.

The temporal lobes provide the perception and processing of sounds, smells, visual images, and the integration of data from all touch analyzers, memorization, experience, emotional perception of the world.

Damage to the parietal lobes of the brain results in a variety of cognitive impairments - spatial orientation disorder, alexia, apraxia (inability to perform purposeful actions), agraphia, acalculia, left-right orientation disorder.

The occipital lobes are visual analyzer. Its functions are visual fields, color perception and recognition of faces, images, colors and the relationship of objects with colors.

Cerebellar lesions cause cerebellar cognitive affective syndrome with blunting emotional sphere, disinhibited by inappropriate behavior, speech disorders - decreased speech fluency, the appearance of grammatical errors.

Causes of cognitive disorders

Cognitive impairments can be temporary, after a traumatic brain injury, poisoning and recover in a time interval from days to years, or they can have a progressive course - in Alzheimer's disease, Parkinson's disease, and vascular diseases.

Vascular diseases of the brain are the most common reason cognitive disorders to varying degrees severity from minimal disorders to vascular dementia. The first place in the development of cognitive impairment is occupied by arterial hypertension, followed by occlusive atherosclerotic lesions great vessels, their combination, aggravated acute disorders blood circulation - strokes, transient attacks, disorders of systemic circulation - arrhythmias, vascular malformations, angiopathy, disorders of the rheological properties of blood.

Metabolic disorders due to hypothyroidism, diabetes mellitus, renal and liver failure, vitamin B12 deficiency, folic acid, with alcoholism and drug addiction, abuse of antidepressants, antipsychotics, tranquilizers can cause the development of dysmetabolic cognitive disorders. At timely detection and treatment they can be reversible.

Therefore, if you yourself notice any intellectual deviations that have appeared in yourself, consult a doctor. The patient himself may not always realize that something is wrong with him. A person gradually loses the ability to think clearly, remember current events and at the same time clearly remember old ones, intelligence and spatial orientation decrease, the character changes to irritable, mental disorders are possible, and self-care is impaired. Relatives may be the first to notice disturbances in daily behavior. In this case, bring the patient for examination.

Testing for cognitive impairment

To determine the presence of cognitive dysfunction, the baseline level is taken into account. Both the patient and relatives are interviewed. Cases of dementia in the family, head injuries, alcohol consumption, episodes of depression, taken medicines.

During examination, a neurologist can detect the underlying disease with corresponding neurological symptoms. Analysis mental state carried out according to various tests, tentatively by a neurologist and in depth by a psychiatrist. Attention, reproduction, memory, mood, following instructions, creative thinking, writing, counting, and reading are examined.

The short MMSE (Mini-mental State Examination) scale is widely used - 30 questions for an approximate assessment of the state of cognitive functions - orientation in time, place, perception, memory, speech, performance of a three-stage task, reading, drawing. MMSE is used to assess the dynamics of cognitive functions, the adequacy and effectiveness of therapy.

Mild decline in cognitive functions - 21 - 25 points, severe - 0 - 10 points. 30 – 26 points is considered the norm, but the initial level of education should be taken into account.

A more accurate clinical rating scale for dementia (Clinical Dementia Rating scale - CDR) is based on a study of disturbances in orientation, memory, interactions with others, behavior at home and at work, and self-care. On this scale, 0 points is normal, 1 point is mild dementia, 2 points is moderate dementia, 3 – severe dementia.

The Frontal Dysfunction Battery is used to screen for dementias with predominant involvement of the frontal lobes or subcortical cerebral structures. It's more complex technique and violations of thinking, analysis, generalization, choice, fluency of speech, praxis, and reaction of attention are determined. 0 points – severe dementia. 18 points – the highest cognitive abilities.

The clock drawing test is a simple test where the patient is asked to draw a clock - a clock face with numbers and arrows pointing certain time can be used for differential diagnosis of frontal type dementia and in cases of damage to subcortical structures from Alzheimer's.

For a patient with acquired cognitive deficit, it is necessary to carry out laboratory examination: blood test, lipid profile, determination thyroid-stimulating hormone, vitamin B 12, blood electrolytes, liver tests, creatinine, nitrogen, urea, blood sugar.

For neuroimaging of brain damage, computer and magnetic resonance imaging, Dopplerography of the great vessels, and electroencephalography are used.

The patient is examined for the presence somatic diseases – hypertension, chronic diseases lungs, heart.

Conducted differential diagnosis vascular dementia and Alzheimer's disease. Alzheimer's disease is characterized by a more gradual onset, gradual slow progression, minimal neurological disorders, late violation memory and executive functions, cortical type of dementia, absence of walking disorders, atrophy in the hippocampus and temporo-parietal cortex.

Treatment of disorders

Treatment of the underlying disease is mandatory!

Donepezil, galantamine, rivastigmine, memantine (Abixa, Mema), nicergoline are used to treat dementia. Dosages, duration of administration and regimens are selected individually.

To improve cognitive functions, various medications are used pharmacological groups, having neuroprotective properties - glycine, Cerebrolysin, Semax, Somazina, Ceraxon, Nootropil, Piracetam, Pramistar, Memoplant, Sermion, Cavinton, Mexidol, Mildronate, Solcoseryl, Cortexin.
Treatment of hypercholesterolemia is mandatory. This helps reduce the risk of developing cognitive dysfunction. This is following a low-cholesterol diet - vegetables, fruits, seafood, low-fat dairy products; B vitamins; statins – liprimar, atorvastatin, simvatin, Torvacard. Avoid smoking and alcohol abuse.

Consultation with a neurologist on the topic of cognitive impairment

Question: Is it useful to solve crossword puzzles?
Answer: yes, this is a kind of “gymnastics” for the brain. You need to force your brain to work - read, retell, remember, write, draw...

Question: is it possible to develop cognitive impairment in multiple sclerosis?
Answer: yes, the structure of cognitive function deficits in multiple sclerosis consists of disturbances in the speed of information processing, mnestic disturbances (short-term memory), disturbances of attention and thinking, and visual-spatial disturbances.

Question: What are “evoked cognitive potentials”?
Answer: The brain's electrical response to performing a mental (cognitive) task. The neurophysiological method of evoked cognitive potentials is the recording of the bioelectrical responses of the brain in response to the performance of a mental task using electroencephalography.

Question: what medications can you take on your own for mild absent-mindedness, attention and memory problems after emotional overload?
Answer: glycine 2 tablets dissolve under the tongue or ginkgo biloba preparations (Memoplant, Ginkofar) 1 tablet 3 times a day, B vitamins (neurovitan, milgamma) for up to 1 month or nootropil - but here the doctor will prescribe the dosage depending on age and diseases. It’s better to see a doctor right away - you may underestimate the problem.

Neurologist Kobzeva S.V.