Subjective and functional cognitive impairment: diagnostics using biological markers of Alzheimer's disease

Cognitive impairment (CI) is one of the most common disorders in elderly. The development of dementia is usually preceded by subjective (SCI) and mild cognitive impairment (MCI) over several years. Patients with SCI are at increased risk of developing MCI and dementia, but SCI may not progress for a long time and in many cases is functional in nature (functional CI – FCI). The article discusses the manifestations and diagnostic issues of SCI and FCI and the possibilities of diagnosing Alzheimer's disease (AD) at the SCI stage using biological markers for AD in cerebrospinal fluid (CSF). The article presents the results of a long-term follow-up (more than 4 years) of two patients with SCI who showed no significant disturbances in repeated neuropsychological examinations. In one patient with SCI, positive biological markers for AD were found in the CSF, indicating an early (second) stage of AD, while in the other patient the absence of these markers indicated a functional nature of the CI. The article discusses the treatment of patients with SCI and the possibilities of anti-amyloid therapy when the Alzheimer's nature of CI is detected.

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