Memory loss in 20s is serious, may be suffering from neurasthenia, depression, autoimmune encephalitis and other diseases caused. 1. Neurasthenia: Continuing to be in a state of tension or long-term internal conflict may induce neurasthenia, resulting in severe memory loss in the patient’s 20s. May also be accompanied by headaches, dizziness, poor concentration, insomnia and other symptoms. 2. Depression: Parental genetic factors, environmental factors, psychological factors, etc. are common causes of depression, patients may experience severe memory loss, slow thinking, reduced volitional activity, cognitive impairment and other symptoms. 3. Autoimmune encephalitis: If the patient’s central nervous system autoantigen is mistaken by the immune system as foreign antigen, causing immune attack, it will trigger autoimmune reaction and induce autoimmune encephalitis. Patients may experience severe memory loss, mental behavioral abnormalities, cognitive impairment, and seizures. If memory loss is severe in the 20s, it is recommended that the patient go to the hospital for relevant examinations under the guidance of a doctor to clarify the cause of the disease and treat the symptoms in a timely manner.