APOE and dementia: During the period of 2016–2017, the terms “CSF biomarkers,” “deposition,” “predictors,” “apolipoprotein E,” “medial temporal lobe,” and “entorhinal cortex” suggested that hot theme was predictors of mild cognitive impairment progression to dementia, to more accurately identify high-risk groups; During the period of 2018–2019, the terms “prevalence,” “Alzheimer’s association work,” “older adults,” “diagnostic guidelines” suggested that the hottest topics at this stage were the diagnostic criteria of MCI and epidemiological studies.