Biomarkers of Alzheimer’s disease pathology in atypical non‐amnestic clinical phenotypes

Abstract

AbstractBackgroundAlzheimer’s disease (AD) is most commonly presented with memory loss features. However, there are atypical clinical phenotypes including predominant visual, language, executive, behavioural, or motor dysfunction. The goal of our study was to estimate the prevalence of Alzheimer’s pathology in non‐amnestic clinical variants.MethodWe examined 40 patients (17 males, 23 females, 66.1±8.3 yrs) with atypical phenotypes of AD (Table 1). Seven patients had the phenotype of logopenic variant of primary progressive aphasia (lvPPA), 3 patients had the diagnosis of posterior cortical atrophy (PCA), 19 had corticobasal syndrome (CBS), and 11 cases met research criteria of clinical behavioral variant of AD (bvAD). All patients underwent lumbar puncture. CSF biomarkers Abeta‐42 (cutoff 150 pg/mL) and p‐tau181 (cutoff 600 pg/mL) were analyzed. According to the recommendations of International Working Group (2021) we defined probable and possible AD based on clinical phenotype and studied CSF biomarkers.ResultThe overall prevalence of AD pathology in the studied groups was 42.5% (20% for probable diagnosis and 22.5% for possible). All results are presented in Table 1. The highest prevalence of AD pathology in atypical clinical phenotypes was found in the group of PCA (66.7%), the lowest ‐ in the group of bvAD (36.4%). Almost a half of patients in both lvPPA and CBS groups had AD pathology based on biomarkers – 42.9% and 42.2%, respectively.ConclusionThe results showed the importance of verifying AD pathology biomarkers in common (PCA, lvPPA) and uncommon (CBS) phenotypes. Behavioral variant, considered as a rare AD phenotype, in our studied cohort was characterized by relatively high occurrence of positive AD biomarkers. Increasing the use of AD biomarkers in clinical practice and greater recognition of atypical phenotypes can ensure early diagnosis, treatment and care for these patients.