TY  - JOUR
AU  - Lewczuk, Piotr
AU  - Wiltfang, Jens
AU  - Kornhuber, Johannes
AU  - Verhasselt, Anneleen
TI  - Distributions of Aβ42 and Aβ42/40 in the Cerebrospinal Fluid in View of the Probability Theory.
JO  - Diagnostics
VL  - 11
IS  - 12
SN  - 2075-4418
CY  - Basel
PB  - MDPI
M1  - DZNE-2022-00304
SP  - 2372
PY  - 2021
AB  - Amyloid β 42/40 concentration quotient has been empirically shown to improve accuracy of the neurochemical diagnostics of Alzheimer's Disease (AD) compared to the Aβ42 concentration alone, but this improvement in diagnostic performance has not been backed up by a theoretical argumentation so far. In this report we show that better accuracy of Aβ42/40 compared to Aβ1-42 is granted by fundamental laws of probability. In particular, it can be shown that the dispersion of a distribution of a quotient of two random variables (Aβ42/40) is smaller than the dispersion of the random variable in the numerator (Aβ42), provided that the two variables are proportional. Further, this concept predicts and explains presence of outlying observations, i.e., AD patients with falsely negatively high Aβ42/40 ratio, and non-AD subjects with extremely low, falsely positive, Aβ42/40 ratio.
KW  - Alzheimer’s disease (Other)
KW  - amyloid β (Other)
KW  - distribution of a random variable (Other)
KW  - probability theory (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:34943609
C2  - pmc:PMC8700661
DO  - DOI:10.3390/diagnostics11122372
UR  - https://pub.dzne.de/record/163548
ER  -