engleski

The ALZENTIA system: a sensitive non-invasive hidden goal test for early cognitive impairment screening

There is a need to identify reliable predictors of mild cognitive impairment (MCI) and dementia due to Alzheimer's disease (AD) in normal elderly people to enable timely intervention. The Mini- Mental State Examination (MMSE) is the best-known and the most often used short screening tool for providing an overall measure of cognitive impairment in clinical, research, and community settings. However, MMSE is not actually a mental status examination designed to detect dementia as it was originally developed to differentiate organic from functional psychiatric patients. The MMSE has low sensitivity in detecting dementia as well as poor specificity, and low negative (NPV), and positive predictive values (PPV), especially in early-stage AD. A recent systematic review also did not find evidence supporting a substantial role of MMSE as a stand-alone single- administration test in the identification of MCI patients who could develop dementia (Cochrane Database Syst Rev. 2015: CD010783). We have developed a new system (ALZENTIA) that helps detect early MCI, mainly caused by AD. This system consists of original software and hardware, and stems from the original efforts by the late Jan Bures and his colleagues to develop a hidden-goal task (HGT) test in which the human subject has to find a target that is not visible ; instead, the navigation must be based on a previously memorized target position, in relation to the starting position and/or other navigational landmarks (orientation cues). The average duration of the test is approximately 25 min. per subject. Our preliminary results obtained on 91 healthy controls (HC) and 33 MCI patients have been recently published (J. Neurosci. Methods, 2020 ; 332: 108547). Receiver operating characteristic (ROC) analysis revealed that two measurements (variables) reached 85% or higher sensitivity and specificity: combined allocentric-egocentric average error of all 8 attempts, and egocentric average error of the first 4 attempts. The high NPVs (over 90% in almost all subtests and at all prevalences) suggested high discriminative capacity and diagnostic potential for the ALZENTIA system as a tool to detects subjects in healthy population who will progress to MCI. Considering the low sensitivity of the MMSE and Montreal Cognitive Assessment (MoCA) tests currently used for this purpose, we believe that ALZENTIA can significantly improve early identification of MCI patients who will progress to AD.

Alzheimer's disease ; early diagnosis ; hidden-goal task ; mild cognitive impairment ; screening test ; spatial orientation

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