Non‐Alzheimer's amnestic mild cognitive impairment with medial temporal hypometabolism

Abstract

INTRODUCTIONThe increasing use of Alzheimer's disease (AD) biomarkers has led to the recognition of a subgroup of non‐AD amnestic mild cognitive impairment (aMCI) patients who have medial temporal hypometabolism on fluorodeoxyglucose‐positron emission tomography (FDG‐PET).METHODSIn this academic memory‐clinic‐based consecutive series, 16 non‐AD aMCI patients and 28 AD controls matched for sex, age, and baseline Mini‐Mental State Examination (MMSE) were followed for a median duration of 4.5 years. Our primary outcome was the MMSE decline rate over the subsequent years. We also determined the final diagnosis over time.RESULTSFDG‐PET showed more pronounced medial temporal hypometabolism in non‐AD cases and more inferior parietal lobule hypometabolism in AD controls. MMSE decline was slower in non‐AD (β = −0.51) than in AD (β = −2.00) patients. Five non‐AD cases developed frontotemporal dementia years after symptom onset, and one developed dementia with Lewy bodies.DISCUSSIONNon‐AD aMCI patients with medial temporal hypometabolism show slower cognitive decline.Highlights Non‐AD aMCI with medial temporal hypometabolism shows slower cognitive decline than AD. FDG‐PET revealed distinct metabolic patterns between non‐AD aMCI and AD patients. Approximately one‐third of non‐AD aMCI cases developed frontotemporal dementia. Comprehensive diagnostic biomarkers are crucial for non‐AD aMCI characterization.