Validation of the Cognitive Telephone Screening Instruments COGTEL and COGTEL+ in Identifying Clinically Diagnosed Neurocognitive Disorder Due to Alzheimer's Disease in a Naturalistic Clinical Setting.

BACKGROUND: Telephone-based neurocognitive instruments embody valuable tools in identifying cognitive impairment in research settings and lately also in clinical contexts due to the pandemic crisis. The accuracy of the Cognitive Telephone Screening Instrument (COGTEL) in detecting mild- (MiND) and major (MaND) neurocognitive disorder has not been studied yet. OBJECTIVE: Comparison of the utility of COGTEL and COGTEL+, which is enriched with orientation items, with the modified Mini-Mental State Examination (3MS) in detecting MiND and MaND due to Alzheimer's disease (AD) and assessment of the impact of COGTEL face-to-face-versus telephone administration on individual performance. METHODS: The study included 197 cognitively intact individuals (CI), being at least 45 years old, 95 and 65 patients with MiND and MaND due to AD, respectively. In 20 individuals COGTEL was administered both in face-to-face and telephone sessions. Statistical analyses included proportional odds logistic regression models, stratified repeated random subsampling used to recursive partitioning to training and validation set (70/30 ratio), and an appropriate F-test. RESULTS: All studied instruments were significant predictors of diagnostic outcome, but COGTEL+ and 3MS explained more variance relative to the original COGTEL. Except for the validation regression models including COGTEL in which the average misclassification error slightly exceeded 15%, in all other cases the average misclassification errors (%) were lower than 15%. COGTEL administration modality was not related to systematic over- or underestimation of performance on COGTEL. CONCLUSION: COGTEL+ is a valuable instrument in detecting MiND and MaND and can be administered in face-to-face or telephone sessions.

Fluid biomarker agreement and interrelation in dementia due to Alzheimer's disease.

The cerebrospinal fluid (CSF) levels of ß-amyloid 42, total tau, and phosphorylated tau 181 are supposed to be all continuously abnormal in dementia due to Alzheimer's disease (AD), being the most advanced disease stage. The aim of the present study, which included a monocentric and a multicentric sample (N = 119 and 178, respectively), was to investigate the degree of CSF biomarker agreement and interrelation in AD dementia. Based on previously published cut-off values, biomarker values were categorized as positive or negative for AD (dichotomization strategy) and as either positive, negative, or borderline (trichotomization strategy). The statistical analyses relied on distance correlation analysis and kappa (k) statistics. Poor agreement (k < 0.4) and low interrelations between the studied biomarkers were detected in all cases with the exception of the interrelation between the markers total tau and phosphorylated tau 181, especially in the monocentric sample. Interestingly, lower interrelation and agreement degrees were observed in carriers of the Apolipoprotein E ε4 allele compared to non-carriers. The clinical phenotype currently referred to as "AD dementia" is characterized by an inhomogeneous CSF biomarker profile, possibly mirroring the complex genesis of AD-typical dementia symptoms and pointing to the necessity of shedding more light on the hypothesis of biomarker stability over time in symptomatic AD.