Symptoms of cognitive impairment

Symptoms of dementia include cognitive, behavioral, emotional, and daily functioning disorders.

Cognitive impairment is the clinical core of any dementia. Cognitive impairment is the main symptom of this condition, so its presence is mandatory for diagnosis.

Cognitive functions (from the English cognition - "knowledge") are the most complex functions of the brain, with the help of which rational cognition of the world and interaction with it is carried out. Synonyms for the term "cognitive functions" are "higher brain functions", "higher mental functions" or "cognitive functions".

The following functions of the brain are usually considered cognitive.

• Memory is the ability to capture, store and repeatedly reproduce received information.
• Perception (gnosis) is the ability to perceive and recognize information coming from outside.
• Psychomotor function (praxis) is the ability to create, maintain and execute motor programs.
• Speech is the ability to understand and express your thoughts using words.
• Intelligence (thinking) is the ability to analyze information, generalize, identify similarities and differences, make judgments and conclusions, and solve problems.
• Attention is the ability to select the most important information from the general flow of information, concentrate on current activities, and maintain active mental work.
• Regulation of voluntary activity - the ability to voluntarily choose the goal of the activity, build a program to achieve this goal and control the implementation of this program at various stages of the activity. Insufficient regulation leads to a decrease in initiative, interruptions in current activity, increased distractibility. Such disorders are usually designated by the term "dysregulatory disorders".

By definition, dementia is a polyfunctional disorder, so it is characterized by the simultaneous insufficiency of several or all cognitive abilities at once. However, different cognitive functions suffer to different degrees - depending on the causes of dementia. Analysis of the characteristics of cognitive disorders plays an important role in establishing an accurate nosological diagnosis.

The most common type of cognitive disorders in dementias of various etiologies are memory disorders. Severe and progressive memory disorders, first for recent and then for distant life events, are the main symptom of Alzheimer's disease. The disease debuts with memory disorders, then spatial praxis and gnosis disorders join them. Some patients, especially those younger than 65-70 years, also develop speech disorders such as acoustic-amnestic aphasia. Attention and voluntary activity regulation disorders are expressed to a lesser extent.

At the same time, disorders of regulation of voluntary activity become the main clinical characteristic of vascular dementia, dementia with Lewy bodies, and diseases with predominant damage to the subcortical basal ganglia (Parkinson's disease, Huntington's disease, etc.) at the initial stages. Disorders of spatial gnosis and praxis are also present, but have a different nature and therefore do not lead, in particular, to disorientation in the area. Memory disorders are also noted, usually expressed to a moderate degree. Dysphasic disorders are not typical.

For frontotemporal lobar degeneration (frontotemporal dementia), the most typical combination is dysregulatory cognitive disorders and speech disorders such as acoustic-amnestic and/or dynamic aphasia. At the same time, memory for life events remains intact for a long time.

In dysmetabolic encephalopathy, the dynamic characteristics of cognitive activity suffer to the greatest extent: reaction speed, activity of mental processes, increased fatigue and distractibility are characteristic. This is often combined with various degrees of disturbance of the sleep-wake cycle.

Emotional disorders in dementias are most common and expressed in the initial stages of the pathological process and gradually regress later. Emotional disorders in the form of depression are found in 25-50% of patients with the initial stages of Alzheimer's disease and in most cases of vascular dementia and diseases with predominant damage to the subcortical basal ganglia. Anxiety disorders are also very typical, especially in the early stages of Alzheimer's disease.

Behavioral disorders are pathological changes in the patient's behavior that cause concern to him or her and/or those around him or her. Like emotional disorders, behavioral disorders are not required for a diagnosis of dementia, but they are quite common (approximately 80% of patients). Behavioral disorders usually develop at the stage of mild or moderate dementia.

The most common behavioral disorders include the following.

• Apathy - decreased motivation and initiative, absence or reduction of any productive activity of the patient.
• Irritability and aggressiveness.
• Aimless motor activity - walking from corner to corner, wandering, moving things from place to place, etc.
• Sleep disorders - daytime sleepiness and psychomotor agitation at night (the so-called sunset syndrome).
• Eating disorders - decreased or increased appetite, changes in food preferences (for example, increased cravings for sweets), hyperoralism (constant chewing, sucking, smacking, spitting, eating inedible objects, etc.).
• Lack of criticality - loss of a sense of distance, immodest or tactless questions and comments, sexual incontinence.
• Delusion - persistent false conclusions. The most typical delusions are those of damage (relatives stealing or plotting something evil), jealousy, doubles (the spouse has been replaced by an outwardly very similar ill-wisher), delusions of the type "I am not at home".
• Hallucinations are usually visual, in the form of images of people or animals, and less often auditory.

Disorders of daily activities are an integral result of cognitive and behavioral symptoms of dementia, as well as other neurological disorders associated with the underlying disease of the brain. The term "disorders of daily activities" means disorders of professional, social and everyday adaptation of the patient. The presence of disorders of daily activities is evidenced by the impossibility or significant difficulties at work, when interacting with other people, performing household duties, and in severe cases - in self-care. The presence of disorders of daily activities indicates a greater or lesser loss of independence and autonomy by the patient, with the need for outside help.

The following types of activities are considered to be part of the sphere of everyday activity:

• professional - the ability to continue to perform one's job effectively;
• social - the ability to interact effectively with other people;
• instrumental - the ability to use household appliances;
• self-service - the ability to dress, perform hygiene procedures, eat, etc.

The timing of development and the sequence of occurrence of certain symptoms of dementia are determined by the nature of the underlying disease, but some of the most general patterns can be traced.

As a rule, dementia is preceded by a stage of mild cognitive impairment (MCI). Mild cognitive impairment is usually understood as a decrease in cognitive abilities that clearly goes beyond the age norm, but does not significantly affect daily activities.

Modified diagnostic criteria for mild cognitive impairment syndrome (Touchon J., Petersen R., 2004)

• Cognitive impairment according to the patient and/or his immediate environment (the latter is preferable).
• Evidence of recent decline in cognitive ability compared to the individual's normal range.
• Objective evidence of cognitive impairment obtained using neuropsychological tests (a decrease in neuropsychological test results of at least 1.5 standard deviations from the average age norm).
• There are no disturbances in the patient's usual forms of daily activity, but there may be difficulties in complex types of activities.
• Dementia is absent - the Mini-Mental State Examination result is at least 24 points,

At the stage of moderate cognitive impairment, the patient complains of memory impairment or decreased mental performance. These complaints are confirmed by neuropsychological examination data: objective cognitive impairments are revealed. However, cognitive impairments at this stage are expressed to a small degree, so they do not significantly limit the patient's usual daily activity. At the same time, difficulties in complex and unusual types of activity are possible, but patients with moderate cognitive impairments retain their ability to work, they are independent and self-sufficient in social life and everyday life, and do not need outside help. Criticism of their condition is most often preserved, so patients, as a rule, are adequately alarmed by changes in their cognitive status. Moderate cognitive impairments are often accompanied by emotional disorders in the form of anxiety and depression.

Progression of disorders and the emergence of difficulties in the patient's usual activities (usual work, interaction with other people, etc.) indicate the formation of mild dementia syndrome. At this stage, patients are fully adapted within their apartment and the immediate area, but experience difficulties at work, when navigating in unfamiliar areas, driving a car, making calculations, making financial transactions and other complex activities. Orientation in place and time is usually preserved, but due to memory disorders, an erroneous determination of the exact date is possible. Criticism of one's own condition is partially lost. The range of interests narrows, which is associated with the inability to maintain more intellectually complex types of activity. Behavioral disorders are often absent, while anxiety-depressive disorders are very common. An exacerbation of premorbid personality traits is very typical (for example, a thrifty person becomes greedy, etc.).

The emergence of difficulties within one's own home is a sign of transition to the stage of moderate dementia. At first, difficulties arise in using household appliances (the so-called impairments of instrumental daily activities). Patients forget how to cook food, use a TV, telephone, door lock, etc. There is a need for outside help: at first only in certain situations, and then - most of the time. At the stage of moderate dementia, patients are usually disoriented in time, but are oriented in place and their own person. A significant decrease in criticism is noted: patients in most cases deny having any memory impairment or other higher brain functions. Behavioral disorders are quite typical (but not obligatory), capable of reaching significant severity: irritability, aggressiveness, delusional ideas, inadequate motor behavior, etc. As the pathological process progresses further, difficulties with self-care (dressing, performing hygiene procedures) begin to appear.

Severe dementia is characterized by almost complete helplessness of the patient in most everyday situations, which requires constant outside assistance. At this stage, delirium and other behavioral disorders gradually regress, which is associated with increasing intellectual disability. Patients are disoriented in place and time, there are pronounced disorders of praxis, gnosis and speech. Significant severity of cognitive disorders makes differential diagnostics between various nosological forms of dementia very difficult at this stage. Neurological disorders, such as gait and pelvic disorders, join in. The final stages of dementia are characterized by loss of speech, inability to walk independently, urinary incontinence and neurological symptoms of decortication.

The main stages of dementia development:

• mild cognitive impairment;
• violation of professional and social activities;
• decreased criticism, personality change;
• disruption of instrumental daily activities;
• formation of behavioral disorders;
• self-care disorder;
• loss of speech, pelvic disorders, urinary incontinence;
• decortication.

Characteristics of the main stages of cognitive deficit

Stage	Cognitive functions	Emotional and behavioral disorders	Daily activities
Mild cognitive impairment	Minor violations with intact criticism	Anxiety-depressive disorders	Not violated
Mild dementia	Severe impairments with decreased criticism	Anxiety-depressive disorders. Personality changes	Professional and social activity is impaired. The patient is independent at home.
Moderate dementia	Marked impairments with decreased criticism. Disorientation in time	Delirium, aggression, aimless motor activity, sleep and appetite disturbances, tactlessness	Impaired instrumental daily activities. Sometimes requires outside help.
Severe dementia	Gross violations. Disorientation in place and time	Regression of delusion, lack of initiative	Impaired self-care. Constantly needs outside help.

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