Severe memory loss may be caused by Alzheimer’s disease, cerebral infarction, brain tumor and other diseases. 1. Alzheimer’s Disease: Alzheimer’s Disease is a disease caused by genes, lifestyle, environmental factors, etc. Patients will suffer from impaired memory, aphasia, emotional apathy and other symptoms, and patients will suffer from severe memory loss. 2. Cerebral infarction: Cerebral infarction is a disease caused by atherosclerosis of large arteries, cardiogenic embolism, occlusion of small arteries, etc. The patient mainly manifests symptoms such as impaired consciousness, coma, hemiparesis, aphasia, etc., and the patient will suffer from severe memory loss. 3. Brain tumor: brain tumor is considered to be a disease caused by ionizing radiation, viral infection, neurological carcinogen, etc. The main symptoms of patients are headache, vomiting, vision loss, aphasia, sensory disorder, etc., and the patients will have symptoms of severe memory loss. When patients experience symptoms of severe memory loss, they should consult a doctor in time to find out the specific cause of the disease and follow the doctor’s instructions for symptomatic treatment.