The disease may be a heterogeneous group of disorders that develop in response to multiple factors, including biological and psychosocial factors. From current studies, there are more than 30 possible factors and hypotheses for the disease, such as family history, female, head trauma, low education level, thyroid disease, high or low maternal childbearing age, and viral infection. The following factors are associated with the development of the disease: 1. Family history The vast majority of epidemiological studies suggest that family history is a risk factor for the disease. Some patients have a higher risk of having family members with the same disease than the general population, and an increased risk of congenital stupidity has also been found. Further genetic studies have confirmed that the disease may be due to autosomal dominant genes. Recently, gene localization studies have revealed that the pathogenic gene for amyloid in the brain is located on chromosome 21. It is clear that dementia is more definitely genetically related. Congenital dysmorphic disorder (DS) has similar pathological changes, and the chance of DS occurring in adults is about 100%, and the gene responsible for DS is known to be located on chromosome 21, which has aroused great interest in the genetics of the disease. St. George-Hyslop et al. (1989) reviewed data from a family lineage study of the disease and found that the risk of the disease in family members was 14.4% for parents and 3.8%-13.9% for siblings. Using lifespan statistics, the risk of the disease in first-degree relatives with FAD was as high as 50%, whereas in controls it was only 10%. These data support the idea that some of the early-onset FAD is a group of dominant autosomal dominant inheritance associated with age; in the literature, there is one female only family with the disease, and X-linked inheritance can be excluded because it is very rare, while most of the disseminated cases may be the result of the interaction of genetic susceptibility and environmental factors. There are at least four known genetic loci associated with AD: the early-onset AD locus is located on chromosomes 2l, 14, and 1, respectively. The corresponding probable causative genes are APP, S182 and STM-2 genes. The late-onset AD locus is located on chromosome 19, and the probable causative gene is the apolipoprotein E (APOE) gene. 2. Some physical diseases such as thyroid disorders, immune system disorders, and epilepsy have been studied as risk factors for the disease. Those with a history of hypothyroidism have a high relative risk of developing the disease. A history of seizures prior to the onset of the disease is more frequent. A history of migraine or severe headache is not associated with the disease. A number of studies have found a history of depression, especially in old age, to be a risk factor for the disease. A recent case-control study suggested an association with other functional psychiatric disorders such as schizophrenia and paranoid psychosis in addition to depression. Chemicals that have been studied as risk factors for the disease include heavy metal salts, organic solvents, pesticides, and pharmaceuticals. The role of aluminum has been of interest because animal studies have shown that aluminum salts have an effect on learning and memory; epidemiological studies suggest that the prevalence of dementia is related to the amount of aluminum in drinking water. It is possible that the aging process is accelerated due to the accumulation of neurotoxins such as aluminum or silicon in the body. 3, head trauma Head trauma refers to head trauma with impaired consciousness, and traumatic brain injury has been reported more frequently as a risk factor for the disease. Clinical and epidemiological studies suggest that severe traumatic brain injury may be one of the causes of some of these diseases. 4, other Progressive failure of the immune system, weakened detoxification and lentiviral infections, as well as psychosocial factors such as widowhood, solitude, economic hardship, and life hardship can be causative factors for the development of the disease.