The diagnosis of senile dementia must first meet the diagnostic criteria for dementia, primarily characterized by impairment in multiple cognitive areas such as memory, language skills, executive function, and computational ability, and these impairments affect daily life; this is called senile dementia. Before dementia occurs, there are some precursory signs, mainly slight declines in memory. For example, patients might occasionally forget to bring keys when going out, or forget to turn off the stove while cooking. These mild memory impairments are some of the precursors to senile dementia. Additionally, there is a decline in learning ability, including the symptoms of learning new knowledge and mastering new skills; these declines are also precursors to senile dementia. Therefore, the precursors of senile dementia can primarily be summarized as a slight decline in memory function and some slight decline in learning ability.