OBJECTIVE

To evaluate the frequency of Alzheimer’s disease (AD) confirmed by cerebrospinal fluid (CSF) biomarkers in a cohort of patients with classical (amnesic) and atypical phenotypes of this disease.

MATERIAL AND METHODS

The study included 63 patients (24 men and 39 women; median age 65 years [60; 71]). All patients were divided into 3 groups according to the phenotype: a classic amnesic phenotype (n=32), frequent non-amnesic phenotypes (n=21) and rare non-amnesic phenotypes (n=10). All patients underwent lumbar puncture followed by the CSF biomarkers evaluation (beta-amyloid 1—42 (Aβ1—42) and phosphorylated tau protein 181 (p-tau181)) to confirm the AD pathology. The clinical characteristics of each subgroup were studied.

RESULTS

A decreased level of CSF Aβ1—42 in combination with an increased level of p-tau181 was found in 36 patients (57.1%). A change in at least one biomarker was detected in 54 patients (85.7%). The highest frequency of the Alzheimer’s type pathology was found in the group with predominant amnestic phenotype (87.5%), as well as in the subgroups with logopenic variant of primary progressive aphasia (lvPPA) (100%) and with posterior cortical atrophy (PCA) (100%). In the group with rare phenotypes, the frequency of AD CSF changes characteristic of AD was 50% for patients with predominant behavioral disorders and 66.7% for corticobasal syndrome.

CONCLUSION

The high frequency of AD CSF biomarkers in both the classical (amnesic) and atypical phenotypes is shown. This indicates the need to expand the use of AD CSF biomarkers for a more reliable assessment of the prevalence of AD In Russia.