The predictive factors of dementia conversion in amyloid‐negative amnestic mild cognitive impairment

Abstract

AbstractBackgroundAround 15–20% of patients with clinically probable Alzheimer’s disease have been found to have no significant Alzheimer’s pathology on amyloid PET. A previous study shows that conversion to dementia from amyloid‐negative mild cognitive impairment (MCI) was observed in up to 11% of patients, drawing attention to this condition. We gathered the detailed neuropsychological and neuroimaging data of this population to elucidate factors for conversion to dementia from amyloid‐negative amnestic MCI.MethodThis study was a retrospective cohort study of patients over the age 50 with amyloid‐negative amnestic MCI who visited the memory clinic of Asan Medical Center with no less than a 36 months follow‐up period. All subjects underwent detailed neuropsychologic tests, three tesla brain magnetic resonance imaging (MRI) scans including 3‐dimensional T1 imaging, and fluorine‐18[F18]‐florbetaben amyloid PET scans.ResultDuring the 36 months of follow‐up, 39 of 107 (36.4%) patients converted to dementia from amnestic MCI. The volumetric analysis revealed that the converter group had significantly reduced total hippocampal volume on the right side, gray matter volume in the right lateral temporal, lingual gyri, and occipital pole. In terms of cerebellar gray matter (GM) volumetric analysis, reduced Crus I/II volume adjusted with total intracranial volume (TIV) and age was observed in the converter group. The converter group had also more severe impairments in all visual memory tasks.ConclusionOur study showed that the reduced gray matter volume related to visual memory processing in the cerebrum and Significant cerebellar GM atrophy involving the bilateral Crus I/II may predict the clinical progression in this amyloid‐negative MCI population.