O1–04–03: Association between memory and amyloid deposition and synaptic dysfunction in EMCI, LMCI and Alzheimer's disease patients

Deficits in list of words or history recall performance is associated with regional declines in brain metabolism, neurodegeneration and amyloid deposition. However, little is known regarding the neurocorrelates of these tests in early stages of AD. Here we aimed to investigate the association between these tests and synaptic depletion and amyloid deposition measured by [18 F]FDG and [18 F]AV45 respectively We analyzed a subsample of participants from ADNIGO & ADNI2 who had clinical, neuropsychological, and [18F]AV45/[18F]FDG data collected in a single visit. Diagnosis of cognitively normal (CN), early mild cognitive impairment (EMCI), late mild cognitive impairment (LMCI) and AD was adjusted using ADNI2 guidelines. Scores on the Rey Auditory Verbal Learning Test 30 min delay (RAVLT30), total recall (RAVLTT), sum of trials (RAVLTST), Logical Memory 30 min delay (LM) were obtained from the ADNI database. RAVLTST was calculated by adding the 5 initial trials of the Rey Auditory Verbal Learning Test. T1 MRIs underwent non-uniformity correction, were skull-stripped and nonlinearly registered to MNI152 space. After registration to MRI, PET uptake ratios were calculated dividing [18F]AV45 and [18F]FDG scans by the median counts of cerebellar-gm and pons, respectively. PET images were subsequently registered to MNI152 space. Voxel-based (age corrected) regression between PET images and LM, RAVLT30, RAVLTT and RAVLST were calculated with PET-UR resampled to MNI space and blurred with a 6mm Gaussian filter. Demographics are summarized in table 1. [18 F]FDG uptake correlated positively (Figure 1) with RAVLT30 and RAVLTST in the hippocampus of EMCI. Hypometabolism correlated with LM (left hippocampus) in LMCI and with RAVLTST (temporal lobe) in AD. [18 F]AV45 uptake(Figure 2) correlated negatively with LM (temporal and parietal) and RAVLTT (parietal) in controls and with RAVLT30, RAVLTT and RAVLTST in the frontal and parietal lobes of EMCI. For all groups collapsed, all tests correlated with brain hypometabolism and [18 F]AV45 uptake in temporal, parietal and frontal areas RAVLT30 and RAVLTST convey neurodegeneration in EMCI while LM reflects neurodegeneration in LMCI. LM30 correlates with amyloid deposition only in controls, while RAVLT30, RAVLTT and RAVLTST reflect amyloidosis in EMCI. Shows significant correlation between [18F]FDG uptake ratio and Logical memory 30 min delay, Rey auditory verbal learning test 30 min delay (RAVLT30) and Rey auditory verbal learning test sum of trails (RAVLTST) scores in early and late MCI. Shows significant correlation between [18F]AV45 uptake ratio and Logical memory 30 min delay, Rey auditory verbal learning test 30 min delay Rey auditory verbal learning test total recall (RAVLTT) and Rey auditory verbal learning test sum of trials scores in controls and early MCI

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