Diagnostic Accuracy of the Five-Word Test for Mild Cognitive Impairment Due to Alzheimer's Disease

Abstract

New diagnostic methods have been developed for the early diagnosis of Alzheimer’s disease (AD) with the primary purpose of intercepting the transition-phase (mild cognitive impairment, MCI) between normal aging and dementia. We aimed to explore whether the five-word test (FWT) and the mini-mental state examination (MMSE) are predictive for the early diagnosis of MCI due to AD (AD-MCI). We computed ROC analyses to evaluate the sensitivity and specificity of MMSE and FWT in predicting abnormal CSF (t-Tau, p-Tau181, Aβ1−42) and amyloid-PET biomarkers. AD-MCI patients showed lower MMSE and FWT scores (all p < 0.001) than non-AD-MCI. The best predictor of amyloid plaques’ presence at amyloid-PET imaging was the encoding sub-score of the FWT (AUC = 0.84). Both FWT and MMSE had low/moderate accuracy for the detection of pathological CSF Aβ42, t-Tau and p-Tau181 values, with higher accuracy for the t-Tau/Aβ1−42 ratio. In conclusion, the FWT, as a single-domain cognitive screening test, seems to be prompt and moderately accurate tool for the identification of an underlying AD neuropathological process in patients with MCI, supporting the importance of associating biomarkers evaluation in the work-up of patients with dementing neurodegenerative disorders.

Keywords: AD-MCI; Aβ1–42; CSF biomarkers; amyloid-PET imaging; five-word test; mini-mental state examination; p-Tau181; t-Tau.

Figure 1

ROC curves for (A) amyloid-PET, (B) CSF Aβ_1–42, (C) CSF t-Tau and (D) CSF p-Tau₁₈₁. ROC: receiver operating characteristics; MMSE: mini-mental state examination (blue line); FWT: five-word test; IRS: immediate recall score (green line); DRS: delayed recall score (orange line); TRS: total recall score (purple line); CSF: cerebrospinal fluid.