Depression in the elderly is normal and not pathological when faced with a sudden and significant mental stimulus and occurs for a period of time. Only when there are persistent symptoms of depression that progress to a severe level can the disease be considered. In addition, people will develop Alzheimer’s disease in old age, and some patients with depression in old age, when the disease develops to a serious stage, the patient’s thinking and movement will be inhibited (especially thinking inhibition), then the clinical manifestations will appear similar to Alzheimer’s disease. Therefore, we should pay special attention to identify the existence of “fake dementia and real depression” in these patients, in order to avoid misunderstanding the disease, delaying treatment and affecting recovery. How to distinguish geriatric depression from dementia? 1. Geriatric depression starts quickly and develops rapidly, while Alzheimer’s disease starts slowly and develops slowly. 2.The depressive symptoms of geriatric depression last longer; the mood of Alzheimer’s disease patients is more variable, unstable and unpredictable, just like a young child. 3.The intellectual impairment of patients with geriatric depression is temporary and partial, and the results of each examination are different; whereas the intellectual impairment of patients with senile dementia is comprehensive and progressive deterioration. 4. Patients with senile depression have no central nervous system symptoms and no positive findings on brain CT examination; this is not the case for patients with senile dementia, who may have central nervous system symptoms and signs. Many patients also have a history of hypertension, arteriosclerosis or “mini-stroke”, and brain CT examination can reveal different degrees of brain atrophy or (and) brain infarction. 5.After using antidepressant drugs, the old age depression patients will be cured and resume their pre-morbid laughter and talk freely; but for Alzheimer’s patients, antidepressant drugs will not play any role. Of course, some patients with Alzheimer’s disease, in the early stage of the disease, can also appear depressive symptoms, rather like “old age depression”, to the middle and late stage of the disease, only to reveal the “true face of Alzheimer’s disease”.