Dementia in Alzheimer's Disease - Diagnosis

Criteria for clinical diagnosis of Alzheimer's disease NINCDS/ADRDA (according to McKhann et al., 1984)

1. A clinical diagnosis of possible Alzheimer's disease can be made when:
   • the presence of dementia syndrome in the absence of other neurological, psychiatric or systemic diseases capable of causing dementia, but with atypical onset, clinical manifestations or course;
   • the presence of a second systemic or neurological disease that can cause dementia, but cannot be considered as the cause of dementia in this case;
   • a gradually progressive, severe impairment of one cognitive function in the absence of other causes identified in scientific research
2. The criteria for a clinical diagnosis of probable Alzheimer's disease are as follows:
   • dementia established by clinical examination, Mini-Mental State Examination (MMET) or similar tests and confirmed by neuropsychological examination; impairment in two or more cognitive areas;
   • progressive deterioration of memory and other cognitive functions;
   • absence of disturbances of consciousness;
   • onset of the disease between the ages of 40 and 90, more often after 65 years;
   • absence of systemic disorders or other diseases of the brain that could lead to progressive impairment of memory and other cognitive functions
3. The following signs confirm the diagnosis of probable Alzheimer's disease:
   • progressive impairment of specific cognitive functions such as speech (aphasia), motor skills (apraxia), perception (agnosia);
   • disturbances in daily activities and changes in behavior;
   • a burdened family history of this disease, especially with pathological confirmation of the diagnosis;
   • Results of additional research methods:
   • no changes in cerebrospinal fluid during standard examination;
   • no changes or nonspecific changes (eg, increased slow wave activity) on the EEG,
   • presence of cerebral atrophy on CG with a tendency to progression during repeated studies
4. Criteria for diagnosis of definite Alzheimer's disease:
   • clinical criteria for probable Alzheimer's disease and histopathological confirmation by biopsy or autopsy

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DSM-IV Diagnostic Criteria for Alzheimer's Dementia

A. Development of multiple cognitive impairment, manifested by the following two signs:

1. Memory impairment (impaired ability to remember new or recall previously learned information)
2. One (or more) of the following cognitive disorders:
   • aphasia (speech disorder)
   • apraxia (impaired ability to perform actions despite the preservation of basic motor functions)
   • agnosia (impaired ability to recognize or identify objects despite the preservation of basic sensory functions)
   • disorder of regulatory (executive) functions (including planning, organization, step-by-step implementation, abstraction)

B. Each of the cognitive impairments specified in criteria A1 and A2 causes significant impairment in functioning in the social or occupational spheres and represents a significant decline in relation to the previous level of functioning

B. The course is characterized by a gradual onset and a steady increase in cognitive impairment.

D. The cognitive impairments covered by criteria A1 and A2 are not caused by any of the following diseases:

• other central nervous system disease causing progressive impairment of memory and other cognitive functions (eg, cerebrovascular disease, Parkinson's disease, Huntington's disease, subdural hematoma, normal pressure hydrocephalus, brain tumor)
• systemic diseases that can cause dementia (hypothyroidism, vitamin B12 deficiency, folic acid or nicotinic acid deficiency, hypercalcemia, neurosyphilis, HIV infection)
• conditions caused by the introduction of substances

D. Cognitive impairment does not develop exclusively during delirium.

E. The condition is not better explained by the presence of another Axis I disorder (eg, major depressive disorder, schizophrenia).

Despite the large number of diseases that can lead to the development of dementia, differential diagnosis is facilitated by the fact that approximately 80-90% of all dementias are degenerative or vascular. Vascular variants of dementia account for about 10-15% of all dementias and are represented by "multi-infarct dementia" and Binswanger's disease. The main cause of both forms is hypertension; in second place is atherosclerosis; then - cardiogenic cerebral embolism (most often with non-valvular atrial fibrillation), etc. It is not surprising that both forms are sometimes combined in one patient. Multi-infarct dementia is manifested by multiple foci of rarefaction (cortical, subcortical, mixed) of brain tissue on MRI, Binswanger's disease - diffuse changes in the white matter. The latter are designated on MRI as leukoareosis (leukoareosis). Leukoaraiosis appears on CT or MRI (T2-weighted imaging) as patchy or diffuse decreased white matter density in the periventricular area and centrum semiovale.

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