With the increasing trend of population aging, the issue of the elderly has become a hot topic of public concern, and the frequent occurrence of dementia has become an important factor affecting the health of the elderly and family happiness. So, how should we pay attention to the problem of dementia in the elderly and make their sunset-like old age shine? This article details the epidemiology of dementia and the early manifestations of dementia, and makes suggestions for the prevention and treatment of dementia. Dementia is a syndrome of persistent, acquired intellectual impairment caused by brain dysfunction and manifests as an acquired progressive intellectual disability. Dementia usually presents as a group of symptoms that are both chronic and progressive in nature. Patients exhibit impairment in thinking, memory, comprehension, calculation, language, judgment, orientation, learning, and some personality changes in the waking state. Etiologically, dementia includes the following types: neurodegenerative dementia (commonly known as Alzheimer’s disease, “senile dementia”, but also frontotemporal dementia, Lewy body dementia, Parkinson’s disease, etc.); vascular dementia (multiple infarct dementia, single infarcts at critical sites, watershed infarct dementia, subcortical arteriosclerotic encephalopathy, hemorrhagic dementia, autosomal dominant disorders combined with subcortical infarcts and leukoencephalopathy), and other causes of dementia (including infection-related, such as K-Y disease; substance abuse related, such as alcohol-dependent dementia; nutritional deficiency related, such as vitamin B12 deficiency, folic acid deficiency; hypothyroidism, uremic syndrome, etc.). Among dementia in old age, Alzheimer’s disease and vascular dementia account for the majority of cases, with Alzheimer’s disease accounting for 60-80% of dementia and vascular dementia for 20%. 1.Dementia epidemiology Every 7 seconds, one person with dementia is born worldwide, and dementia is a common challenge for all human beings. The situation in China is also extremely serious. The prevalence of dementia among the elderly over 65 years old in China is about 7.8% (of which senile dementia and vascular dementia account for 4.8% and 1.1% respectively). Epidemiological and statistical studies have found that the incidence of dementia has a clear age dependence, i.e., the incidence is low in youth, gradually increases in middle age, and surges in old age, with a prevalence of 0.3-1.0% between 60 and 64 years old, 20% between 80 and 90 years old, and 40% above 90 years old. With the aging of China’s population structure, it is now tentatively estimated that there are as many as 10 million dementia patients in China, accounting for more than a quarter of the total number of cases in the world. In a stratified random survey of 5276 people aged 55 and above in Guangzhou, 183 people were found to have dementia, with a crude prevalence rate of 3.47%, of which the crude prevalence rates of senile dementia, vascular dementia and other dementias were 2.43%, 0.85% and 0.19% respectively. 2.How to detect dementia early? Near-memory deficits, decreased ability to learn new knowledge and acquire new skills, mood changes, and personality disorders are common early manifestations of dementia. (1) Near-memory deficits are often the earliest clinical manifestation, mainly due to impaired memory function. However, patients are self-aware of this and seek to mask and compensate for it, often taking a series of auxiliary measures, such as taking detailed written notes or uncharacteristically asking someone to remind them, thus reducing or avoiding the adverse effects of memory deficits on work, society and life, and thus masking the memory loss as a symptomatic manifestation. The overall involvement of memory and deficits in comprehension and judgment may cause delusions that are brief, variable, and unsystematic, usually about theft, loss, suspicion, victimization, or jealousy of a spouse. Impairment of memory and judgment may result in disorientation, with the patient losing the ability to recognize time, place, people, or even themselves. Therefore, they are often unable to distinguish between day and night, do not know the way back or wander aimlessly. (2) Decreased ability to learn new knowledge and acquire new skills, and easy fatigue, frustration and irritation when encountering unfamiliar assignments is another early symptom of dementia. (3) Emotionally, the early stage shows emotional instability, which gradually becomes indifferent and sluggish in the evolution of the disease. Sometimes the emotions lose control and become shallow and changeable. They may be anxious, depressed and negative, indifferent or angry, prone to crying and laughing, and unable to control themselves. Higher emotional activities, such as shame, morality, responsibility and honor are affected at the earliest. (4) Personality disorders can sometimes appear early in the disease. Patients become less energetic, easily fatigued, lose enthusiasm for work, lose interest in activities they used to enjoy, seem inattentive to people and things, sometimes make bad jokes that are out of place, do not pay as much attention to dress and grooming as before, and may become untidy and unkempt. Sometimes there are violations of social and moral norms such as molestation of young children or exposure of the pubic area. Some people become suspicious, stubborn and calculating. Among them, Alzheimer’s disease starts insidiously, develops slowly, often without exact time of onset and symptoms of onset, and is often not easily detected in the early stage, and once it occurs, it progresses slowly and irreversibly. In the early stage, the main manifestations are memory (mainly recent memory) and calculating power, and then there is a gradual development of slow thinking, slow reaction, time and spatial orientation, reduced initiative, change of stubbornness and suspicious personality. In the early stages, there is usually no impairment in limb movement and the patient is still able to take care of himself or herself, while cranial CT and magnetic resonance imaging (MRI) show more extensive brain atrophy. The early symptoms are similar to those of Alzheimer’s disease, but are often accompanied by impaired movement of the limbs. The course of the disease is mostly stepwise, i.e. the disease is stable for a long period of time, not deteriorating or even improving, and the cranial CT and MRI show that there are foci of ischemia or hemorrhage in the brain of varying degrees, and through corresponding treatment, along with the recovery of limb movement disorders, intellectual impairment may also be partially or basically recovered, but with the deterioration of vascular disease, the course of the disease will gradually progress. Early prevention of dementia There is no way to stop the development of Alzheimer’s disease, but active prevention and control measures can be taken early to reduce the prevalence of the disease. There are many risk factors for dementia, including advanced age, positive family history of dementia, cardiovascular disease, depressed mood, emotional depression, living alone, not participating in social activities, illiteracy and low education, lack of physical and mental exercise, long-term smoking, alcohol consumption, over-eating, and obesity. If these risk factors were reduced by 25%, the number of Alzheimer’s patients could be reduced by 3 million per year. Except for age and genetic factors that cannot be changed, all other risk factors can be prevented and slowed down through positive behavioral interventions. For older adults with these risk factors, we suggest the following: (1) Using your brain is a great way to prevent dementia. Once the nerve cells in the brain are damaged, they cannot be repaired, so brain stimulation and exercise can be used to promote the vitality of brain cells and prevent dementia. You should use your brain more, observe and think more often, and keep your career and creativity. You can also write more articles, listen to more music, and learn to raise flowers, plants, and fruits and vegetables. (2) Actively prevent and treat hypertension, diabetes, hyperlipidemia, hyperhomocysteinemia, and arteriosclerosis. The above diseases are the culprits of stroke, which may lead to cerebrovascular dementia. Therefore, long-term effective control of hypertension, diabetes, hyperlipidemia, hyperhomocysteinemia, and atherosclerosis can help prevent Alzheimer’s disease. (3) Change the isolation and go to the society. Actively participate in various forms of activities, such as friends’ gatherings, recreational performances, chess and cards, travel and other activities, all of which help to exercise the brain and increase the interest of life. (4) Avoid all kinds of psychological stressful stimuli. A variety of negative psychological stimuli can contribute to dementia in the elderly, therefore, to deal with a variety of psychological and mental stimuli, should take a “thoughtful” generous calm mind, learn to self-control and regulation of the psyche. (5) Start with diet. Avoid smoking, less alcohol, moderate recreational activities, avoid overwork; reduce salt, sugar intake, food to grain and legumes, while the intake of high-quality protein such as fish, lean meat, eat more vegetables and fruits; control weight. The latest research shows that the aging of people, the decline of immunity, and the occurrence of dementia may be caused by the free radicals. The best substances to prevent and destroy free radicals are antioxidant nutrients, including vitamin C, E, B and carotene intake can eliminate free radicals in the body and prevent dementia. (6) Other: including avoiding the use of aluminum products to reduce the possibility of aluminum poisoning. Prevent traumatic brain injury and regular physical examination. Participate in more exercise, mild people walk 30 minutes a day, walk 5000 steps, have a preventive effect. (7) Of course, optimism and open-mindedness, physical and mental activities and self-confidence are also important factors in the prevention of Alzheimer’s disease. If an elderly person shows early signs of dementia as mentioned above, family members should actively bring him/her to the hospital. The following tests should be performed in cooperation with the doctor: cognitive function and psychiatric symptom assessment, blood tests (including routine blood, blood glucose, lipids, serum homocysteine, electrolytes, liver and kidney function, thyroid function, vitamin B12, syphilis, H I V serology, erythrocyte sedimentation rate), structural neuroimaging (including CT and MRI, which should be performed in all patients with suspected dementia) It can be used to identify hippocampal atrophy, frontotemporal degeneration, vascular dementia and some specific types of dementia), functional neuroimaging (including PET and SPECT, which are often used as a complement to structural imaging in patients with differential diagnostic difficulties), electroencephalography, cerebrospinal fluid analysis (specific biological markers in the cerebrospinal fluid such as AB42, total Tau protein, phosphorylated Tau protein and 142323 protein).