The causes of hippocampal shrinkage are mainly the following: First, if adolescents and children have shrunken hippocampus, consider that the patient has congenital brain dysplasia, which will show shrunken hippocampus, and the patient has mental disorders, memory loss or mood disorders; Second, for example, elderly patients with previous history of hypertension, diabetes, hyperlipidemia or long-term smoking and drinking can also cause arteriosclerosis in the brain and appear temporal lobe infarction, which can also result in hippocampal shrinkage; third, some patients, such as those with Alzheimer’s disease, exhibit atrophy of the cerebral cortex, which can also result in hippocampal shrinkage due to hippocampal atrophy. In short, hippocampal shrinkage is mostly due to the above mentioned reasons. Patients with shrunken hippocampus have memory impairment, emotional disturbance, and in some cases, seizures.