As society develops and the aging process of the population accelerates, the number of patients with dementia is increasing. One of the most common causes is progressive degeneration of the brain, such as Alzheimer’s disease. These diseases are slowly progressive but eventually disabling or even fatal, and no effective prevention or cure has been found by the medical community. If good care is given in the early stages of the disease, it is still possible to slow down the progression as much as possible, and scientific care in the later stages is the key. There are also some causes of dementia that are treatable, such as folic acid and vitamin B12 deficiency, hypothyroidism, hydrocephalus, etc. If effective and early intervention is carried out, dementia can be significantly improved or even cured; the accompanying vascular risk factors such as hypertension, diabetes, hyperlipidemia, hyperhomocysteinemia, obesity, etc. can be improved through active treatment; some occupational risk factors such as hypertension, diabetes, hyperlipidemia, hyperhomocysteinemia, obesity, etc. can be cured. Some occupational risk factors such as organic solvents, electromagnetic fields and lead can be effectively prevented; moderate alcohol and coffee consumption may be protective factors for dementia. In conclusion, the effectiveness of dementia treatment varies depending on the cause, and most degenerative dementias cannot be completely cured.