Correlação entre neuroimagem molecular, estrutural e funcional em superidosos

Abstract

SuperAgers (SA) are older adults at 80 years or above with memory similar to middle-aged adults. These older adults exhibit unique brain features, such as increased cortical thickness of the anterior cingulate cortex and increased functional connectivity within the same region. In this study, we analyze SuperAgers through multimodal neuroimaging using PET with [18F]Fluorodeoxiglicose (FDG) and [11C]Pittsburgh Compound B (PIB), functional MRI (fMRI) and structural MRI (sMRI). Community-dwelling individuals were evaluated with a broad cognitive battery and then classified in 4 groups. SA were defined as individuals at or above 80 years of age and delayed-memory scores similar to middle-aged adults between 50 to 65 years-old, while non-memory tests within the normal range for age. Age-matched Controls (C80) were defined as older adults cognitively normal for age. Middle-aged controls (C50) were defined as individuals between 50 to 65 years-old, cognitively normal for age. All individuals underwent the neuroimaging protocol to measure metabolic activity (PET-FDG), amyloid deposition (PET-PIB), functional connectivity (fMRI), cortical thickness and volume (sMRI). The relationship between cognitive scores and cingulate areas and hippocampus were examined. The SA group showed increased FDG SUVr in the left subgenual Anterior Cingulate Cortex (sACC, p<0.005) as compared to that in the C80 group. Amyloid deposition was similar between SA and C80 in the described regions or overall areas (p>0.05). The SA group also presented decreased connectivity between left sACC and posterior cingulate (p<0.005) as compared to that of C80 group. These results support the key role of ACC in SA, even in the presence of amyloid deposition. It also suggests that sACC can be used as a potential memory biomarker in older adults.