Fig. 24.

Biomarker abnormality in A− N−, A+ N−, SNAP, and A+ N+ MCI patient groups, disaggregated by progressive cognitive deterioration. MCI subjects were grouped on the basis of absence or presence of abnormal levels of amyloid and neurodegeneration. SNAP subjects were neurodegeneration positive but amyloid negative. All four groups significantly differed in CSF Aβ₄₂ concentrations, hypometabolism on FDG PET, and hippocampal volume. SNAP subjects were characterized by more severe hippocampal atrophy than other groups in the absence of abnormal amyloid. Triangles denote progressors, whereas circles denote nonprogressors. Abbreviations: AD, Alzheimer’s disease; A− N−, amyloid negative neurodegeneration negative; A+ N−, amyloid positive neurodegeneration negative; A+ N+, amyloid positive neurodegeneration positive; CSF, cerebrospinal fluid; FDG, [¹⁸F]-fluorodeoxyglucose; MCI, mild cognitive impairment; PET, positron emission tomography; SNAP, suspected non-Alzheimer’s pathology. Reproduced with permission from [291].