Diagnosing preclinical and clinical Alzheimer's disease with visual atrophy scales in the clinical practice

Visual atrophy scales from the medial temporal region are auxiliary biomarkers of neurodegeneration in Alzheimer's disease (AD). Therefore, they may correlate with progression from cognitively unimpaired (CU) status to mild cognitive impairment (MCI) and AD, and they become a valuable tool for diagnostic accuracy.

To compare the medial temporal lobe atrophy (MTA) and entorhinal cortex atrophy (ERICA) scores measured through magnetic resonance image (MRI) scans as a useful method for probable AD diagnosis regarding clinical diagnosis and amyloid positron-emission tomography (PET).

Two neurologists blinded to the diagnoses classified 113 older adults (age > 65 years) through the MTA and ERICA scores. We investigated the correlations involving these scores and sociodemographic data, amyloid brain cortical burden measured through PET imaging with (11)C-labeled Pittsburgh Compound-B (11C-PIB PET), and clinical cognitive status, in individuals diagnosed as CU (CU; N = 30), presenting mild cognitive impairment (MCI, N = 52), and AD patients (N = 31).

The inter-rater reliability of the atrophy scales was excellent (0.8-1) according to the Cohen analysis. The CU group presented lower MTA scores (median value: 0) than ERICA (median value: 1) scores in both hemispheres. The 11C-PIB-PET was positive in 45% of the sample. In the MCI and AD groups, the ERICA score presented greater sensitivity, and the MTA score presented greater specificity. The accuracy of the clinical diagnosis was sufficient and no more than 70% for both scores in AD.

In the present study, we found moderate sensitivity for the ERICA score, which could be a better screening tool than the MTA score for the diagnosis of AD or MCI. However, none of the scores were useful imaging biomarkers in preclinical AD.