Biomarkers

To describe the incidence of medial temporal hypometabolism as a pattern suggestive of LATE in patients with MCI, along with clinical characteristics, amyloid burden, and conversion to AD dementia.

We studied 207 MCI patients (mean age 72±6.1; MMSE 27±2.6; 50.8% male) who underwent FDG-PET and amyloid PET imaging, with follow-up over 24±17.5 months. FDG-PET patterns were classified as LATE-like (medial temporal), AD, and mixed (AD-LATE). Differences among these patterns were analyzed using SPM12, comparing to healthy controls. Amyloid PET was classified visually and quantified using the Centiloid scale. Statistical tests (Chi-square, ANOVA, and Cox regression) were applied to assess clinical features, amyloid burden, and AD dementia conversion rates.

LATE-like patterns were identified in 22 patients (10.6%), AD patterns in 57 (27.5%), and mixed patterns in 21 (10.1%). The remaining 107 patients (51.7%) with non-AD patterns were excluded. The LATE-like group showed prominent medial temporal hypometabolism, while posterior cingulate and parietotemporal hypometabolism were predominant in AD and mixed groups. LATE-like patients had higher MMSE scores, lower amyloid positivity, and lower Centiloid values compared to AD and mixed groups. Conversion to AD dementia was slower in LATE-like patients compared to AD (p = 0.005; HR=0.26 [0.1-0.67]) and mixed (p = 0.02; HR=0.29 [0.11-0.83]).

The LATE-like FDG-PET pattern is not uncommon in MCI. It is linked to better cognitive performance, lower amyloid burden, and slower progression to AD dementia compared to AD and mixed patterns.