Before diagnosing Alzheimer's disease, it is essential to determine whether the patient meets the diagnostic criteria for dementia. A diagnosis of dementia can be made if the following conditions are met: First, there must be impairment in at least two cognitive domains, which may or may not be accompanied by behavioral symptoms. These domains include learning and memory, language function (speaking, listening, reading, and writing), reasoning and judgment, executive function and the ability to handle complex tasks, and visuospatial function. These impairments may or may not be accompanied by changes in personality or behavior. Second, the patient's work ability or daily living activities must be affected. Third, the symptoms cannot be explained by delirium or a psychiatric disorder. Once dementia is confirmed, the patient's age should be considered to determine whether they meet the diagnostic criteria for Alzheimer's disease.