Diagnosis of cognitive impairment

The first stage in diagnosing dementia is to identify cognitive impairment and assess their severity (syndromic diagnosis). For the study of cognitive functions, clinical methods (collection of complaints, anamnesis of the patient) and neuropsychological tests are used. Ideally, every patient with cognitive complaints should undergo a detailed neuropsychological study, but in practice this is hardly possible. Therefore, neurologists, psychiatrists and doctors of other specialties are recommended to use the so-called screening scales of dementia, which take relatively little time and are quite simple in carrying out and interpreting. Most often use a short scale of assessment of mental status and a test drawing hours.

Brief scale of assessment of mental status

The function under study	The task	Number of points
Orientation in time	Name the date (day, month, year, day of the week, time of year)	0-5
Orientation in place	Where are we (country, region, city, clinic, room)?	0-5
Perception	Repeat three words: lemon, key, ball	O
Concentration of attention	Serial account (for example, from 100 to subtract 7) - five times	0-5
Memory	Recall the three words (sounded when checking the perception)	0-3
Naming of objects	What it is? (The patient should name the items shown to him, for example, the pen and watch.)	0-2
Reiteration	Repeat the phrase: "No if, no no"	0-1
Understanding the team	Take the right hand of a sheet of paper, fold it twice and put it on the table	O
Reading	Read aloud what is written ("Close your eyes"), and do it	0-1
Letter	Invent and write some suggestion	0-1
Painting	Draw this drawing	0-1

The total score is 0-30.

Instructions and Interpretation

• Orientation in time. Ask the patient to fully name today's date, month, year, day of the week and time of year. For each correct answer, 1 point is added. Thus, the patient can receive from 0 to 5 points.
• Orientation in place. They ask the question: "Where are we?" The patient should name the country, region, city, institution in which the survey takes place, room number (or floor). For each correct answer the patient receives 1 point. Thus, for this test the patient can also receive from 0 to 5 points.
• Perception. The patient is given the instruction: "Repeat and try to memorize three words: lemon, key, ball." Words must be pronounced as legibly as possible at a speed of one word per second. Correct repetition of each word to patients is estimated at 1 point. After this, we ask the patient: "Remember the words? Repeat them one more time. " If the patient finds it difficult to re-pronounce them, call the words again until the patient remembers them (but no more than 5 times). In points, only the result of the first repetition is evaluated. With this sample, the patient can receive from 0 to 3 points.
• Concentration of attention. Give the following instruction: "Please, from 100 take away 7, from what will turn out, once again take 7 and so do it several times." Use 5 subtractions (to result 65). For each correct subtraction, 1 point is added. The patient can get in this sample from 0 to 5 points. In case of an error the doctor should correct the patient, having prompted the correct answer. The score for an erroneous action does not accrue.
• Memory. They ask the patient to remember the words he memorized while checking his perception. Each correctly named word is rated at 1 point.
• Naming of objects. They show the patient a pen and ask: "What is it?", The clock is similarly used. Each correct answer is rated at 1 point.
• Repeat the phrase. Ask the patient to repeat the following phrase: "No if, no no." The phrase is pronounced only once. Correct repetition is rated at 1 point.

• Understanding the team. Orally give a command that involves the sequential commission of 3 actions. "Take a sheet of paper with your right hand, double it and put it on the table." Each correctly performed action is estimated at 1 point.
• Reading. The patient is given a sheet of paper, on which it is written in large letters: "CLOSE EYES". Give the following instruction: "Read aloud and follow what is written here." The patient receives 1 point, if after a correct reading aloud he really closes his eyes.
• Letter. The patient is asked to come up and write some proposal. The patient receives 1 point if the proposal he devises is meaningful and correct in a grammatical sense.
• Painting. The patient is given a sample (2 intersecting pentagons with equal angles, a quadrilateral is formed at the intersection), which he must redraw on non-liner paper. In the event that the patient redraws both figures, each of which contains five corners, the lines of the pentagons are connected, the figures really intersect, a quadrilateral is formed at the intersection, the patient receives 1 point. If at least one of the conditions is not met, the score does not accrue.

The overall result of the test is obtained by summing the results for each of the items. 24 points or less is typical of dementia.

Clock drawing test

Ask the patient on a non-linear paper to draw a round clock with arrows on the dial indicating a certain time (for example, without 15 minutes 2). The patient draws the clock independently (without prompts), from memory (without looking at the real clock). The result is evaluated on a 10-point system.

• 10 points - the norm, a circle is drawn, the numbers are in the right places, the arrows show the given time.
• 9 points - minor inaccuracies in the position of the arrows.
• 8 points - more noticeable errors in the location of the arrows (one of the arrows deviates from the desired time more than on the hour of the hour).
• 7 points - both hands show a wrong time.
• 6 points - the arrows do not perform their functions (for example, the time is circled or written numerically). .
• 5 points - incorrect arrangement of numbers on the dial (they follow in the reverse order, ie counterclockwise, or the distance between the numbers is not the same).
• 4 points - the integrity of the clock is lost, some numbers are missing or located outside the circle.
• 3 points - the numbers and the dial are not related to each other.
• 2 points - the activity of the patient shows that he is trying to follow the instructions, but without success.
• 1 point - the patient does not attempt to follow the instructions.

Interpretation: less than 9 points - a sign of pronounced cognitive impairment.

Further, one should also assess how cognitive impairments affect the daily activities of the patient. To do this, you need to get information about his professional activities, hobbies and hobbies, degree of independence in social communication, household duties, use of household appliances, self-service. Information received from the patient, it is desirable to check with his relatives, friends or colleagues, because for the early stages of dementia is very typical dissimulation: patients hide their defect or minimize its severity. In the presence of real difficulties in daily activities, it is possible to speak of dementia proper, otherwise the syndromal diagnosis should be formulated as: "mild cognitive impairment" or "moderate cognitive impairment".

The second stage of diagnostic search is the differential diagnosis of dementia and conditions that mimic dementia, such as pseudodementia and delirium.

By definition, dementia is marked primary cognitive impairment, not related causally to emotional disturbances or disturbances in the level of wakefulness or consciousness.

Depressive pseudodegmentia are cognitive and / or behavioral disorders secondary to depression. Such disorders can lead to difficulties in daily activities and mimic dementia, but they do not have an organic substrate and regress when the mood is normal.

Signs of having a patient with depression:

• oppressed or depressed state, marked most of the time during the last month or more;
• feeling of despair, expressed dissatisfaction with one's life, lack of desire to live, frequent thoughts about death, suicidal utterances;
• difficulties of falling asleep or early morning awakenings occurring almost every night;
• chronic headaches (> 15 days per month) or constant heaviness in the head, not allowing to concentrate;
• strong unrestrained anxiety, especially in the evenings, anxiety, irritability, resulting in frequent conflicts in the family or at work;
• marked deterioration of appetite, loss of body weight in the absence of somatic reasons for this;
• expressed concern about memory loss with normal or almost normal results of neuropsychological tests.

The presence of clinically significant depression is the basis for consulting and supervising a psychiatrist and conducting appropriate therapy. In this case, elderly people should avoid drugs with a pronounced anticholinergic effect, such as tricyclic antidepressants. Drugs of this pharmacological group have a negative effect on cognitive functions. Therefore, selective serotonin reuptake inhibitors or serotonin reuptake inhibitors and norepinephrine are more preferred. According to some sources, these drugs, on the contrary, contribute to the improvement of cognitive functions.

Regression of cognitive disorders on the background of the appointment of antidepressants indicates a secondary nature of disorders of higher cerebral functions with respect to depression. In these cases, the diagnosis of pseudodement is justified. If, despite a good antidepressant effect, cognitive disorders persist, it is a combination of true dementia and depression, which is possible with vascular and mixed dementia, Parkinson's disease and other diseases with subcortical basal ganglia lesions with dementia, in the early stages of Alzheimer's disease, temporal dementia. In these cases, a repeated assessment of the violations, clinical laboratory and instrumental research is necessary. Thus, differential diagnosis of pseudodementia and true dementia in combination with depression is carried out by ex juvantibus on the basis of the results of appropriate therapy.

Delirium is an acute state of confusion with pronounced mnestic-intellectual disorders. Suspected of delirium should be in all cases of acute or subacute development of cognitive impairment and in the presence of marked fluctuations in the severity of the disorders, for example, depending on the time of day. Typically, delirium is accompanied by disorientation in place and time, psychomotor agitation and psycho-productive symptoms in the form of delusions and hallucinations. However, these features are not always present. The presence of pronounced cognitive impairments associated with confusion or confusion is deemed essential.

The main causes of delirium in the elderly are as follows.

• Dysmetabolic disorders; dehydration, hepatic or renal insufficiency, hypoxia, hypo- or hyperglycemia, acute intoxication.
• Infectious diseases: pneumonia, urinary infection, any infection with high fever.
• Trauma: craniocerebral injury, including lung, fractures of limbs.
• Operative interventions, especially with the use of general anesthesia.
• Decompensation of cardiac or respiratory failure.

When establishing the cause of delirium and timely correction of dismetabolic or other disturbances, the level of consciousness of the patient is restored, which is accompanied by a significant improvement in cognitive functions. However, cognitive abilities rarely return to the pre-diarrheal state. More often after exiting from the state of acute decompensation, patients show a slight decrease in cognitive functions compared to the baseline level.

The third stage of the diagnostic search is the establishment of a nosological diagnosis of dementia. For this purpose, clinical-laboratory and neuroimaging imaging of patients is performed.

Nosological diagnosis should begin with a search for the so-called potentially reversible dementia. Potentially reversible dementia is a condition where timely diagnosis and proper treatment can lead to complete or almost complete regression of disorders. According to statistics, at least 5% of dementia are potentially reversible. These include the following types:

• dementia secondary to systemic dysmetabolic disorders (dysmetabolic encephalopathy);
• dementia in brain tumors or other volumetric processes;
• Dementia in normotensive hydrocephalus.

The main causes of dismetabolic encephalopathy are the following:

• hypothyroidism;
• deficiency of vitamin B ₁₂ or folic acid;
• liver failure;
• kidney failure;
• chronic hypoxic condition;
• poisoning with salts of heavy metals;
• alcoholism and drug addiction;
• drug intoxication (anticholinergic drugs, tricyclic antidepressants, neuroleptics, benzodiazepines, etc.).

The minimum amount of research necessary to identify these causes is the following:

• general analysis of blood and urine;
• biochemical blood test with the determination of the concentration of creatinine, urea nitrogen, the activity of liver enzymes, if possible - the content of vitamin B ₁₂ and folic acid, homocysteine;
• laboratory examination of thyroid function (content of triiodothyronine, thyroxine, thyroid-stimulating hormone, antibodies to thyroglobulin).

The use of methods of neuroimaging allows to diagnose such potentially reversible brain lesions as normotensive hydrocephalus and brain tumor.

Clinical and visualization signs of normotensive hydrocephalus

Cognitive impairment	Neurological disorders	CT or MRT signs
Infringements of regulation of activity	Violation of gait. Urinary incontinence	Significant symmetrical expansion of the ventricular system

Clinical and visualization signs of a brain tumor

Cognitive impairment	Neurological disorders	CT or MRT signs
Different in severity and qualitative characteristics (depending on the location of the tumor)	Focal symptomatology (depending on the location of the tumor). Headache, stasis on the fundus, vision impairment	Focal damage of the brain, accumulating contrast agent. Ventricular expansion (occlusive hydrocephalus)

Suspicion of the presence of normotensive hydrocephalus or a brain tumor is an occasion for contacting a neurosurgeon, which solves the question of indications for surgical treatment.

After eliminating the potentially reversible forms of dementia, the clinical, psychological and instrumental features of the case should be re-examined.

Comparative characteristics of the main nosological forms of dementia

	Alzheimer's disease	Vascular dementia	Dementia with Levy bodies	Frontal temporal dementia
Start	Always gradual, not earlier than 40 years, more often after 60 years	Acute or gradual, at any age, but more often after 60 years	Gradual, rarely acute, usually after 60 years	Gradual, usually up to 60 years
Family history	Sometimes	Rarely	Sometimes	Often
The main cognitive symptom	Memory malfunction	Disorder irregularities	Visual-spatial disturbances, fluctuations	Disregulatory disorders, speech disorders
Neurological disorders	None	Gait disorders, pseudo-bulbar syndrome	Parkinsonism	"Primitive reflexes" (for example, grasping)
Emotional Disorders	Anxiety, depression at the onset of a disease	Depression, emotional lability	Depression	Indifference, rarely depression
Changes in MRI	Atrophy of the cortex, hippocampus	Postinfarction cysts, leukoareosis	Extension of the posterior horns of the lateral ventricles	Local atrophy of the frontal and anterior parts of the temporal lobes (often asymmetric)
Behavioral disorders	Delirium damage (in the stage of moderate dementia)	Irritability	Visual hallucinations	Reduction of criticism, disinhibition, apathy

[1], [2], [3], [4], [5]