A + T ± status across MCI and dementia due to AD: a clinic-based, retrospective study

Background This study aimed at comparing, within the 2018 NIA-AA amyloidosis/tauopathy/neurodegeneration (ATN) framework, the distribution of T +/- profiles across A+patients with MCI and dementia in a retrospective, single-center, clinic-based cohort.Methods We retrospectively collected data on N=168 A+patients with either MCI due to AD (N=50) or probable AD dementia (ADD; N=118). ATN status was assigned, according to the 2018 NIA-AA framework, based on cerebrospinal fluid (CSF) biomarker concentrations. A chi(2)-test for independent samples was run to compare the distribution of A + T + vs. A + T- profiles, regardless of N status, across MCI and dementia patients.Results The most represented ATN profile in both groups was A+T+N+(MCI: 54%; dementia: 70.3%); 3.4% of dementia patients and none within the MCI cohort presented with an A+T-N+ profile. When grouping ATN profiles solely based on A and T dimensions, the prevalence of A+T+ was of 76.3% and 66% in dementia and MCI patients, respectively. No association between clinical diagnoses (i.e., MCI vs. dementia status) and AT profiles (i.e., A+T+ vs. A+T-) was detected.Discussion The distribution of A+T+ vs. A+T- does not differ between MCI and ADD, with A+T+profiles being predominant in both clinical categories. This does not support the common notion of A+T- profiles being relatively more prevalent in MCI patients, as indexing an earlier and/or less severe disease. Hence, caution should be exerted in attributing a case of MCI to prodromal AD solely based on A-positivity in the presence of a T-negative profile.