Dementia is not a normal aging but rapid degeneration and deterioration of brain functions, leading to the decline of a person’s ability. The patient's cognitive ability will gradually lose, including memory, language ability, visual spatial judgment, execution ability, calculation and decision-making and other aspects, so that daily-living, behavior and emotions are also affected.

At present, one person is diagnosed with dementia every 3 seconds in the world, and there is one patient in every 10 elderly people aged 70 or above in Hong Kong suffering from dementia. The prevalence rate is as high as one-third at the age of 85 years, thus situation cannot be ignored.

Causes and classification of dementia
Alzheimer’s Disease
Alzheimer's disease is the most common type of dementia, accounting for 50% to 75% of all cases. The cause of this degenerative disease is unknown, there is currently no cure, and the patient's decline is gradual. As brain cells develop disease, abnormal substances will be produced in the body to form ""plaques"", disturbing the information in the brain, and destroying the connections between brain cells. The death of brain cells leads to the loss of certain functions or abilities. The problems that arise include memory loss, taking a long time to complete habitual tasks, loss of focus and repetitive speech, etc. When the condition continues to deteriorate, eventually the patient may be bedridden for a long time.
Vascular Dementia
Vascular dementia is the second most common type of dementia. This is due to a series of strokes or vascular diseases, resulting in accumulated brain damage. The decline of patients is mostly cascading, that is, every time a patient has a stroke, their brain function degrades again. Mixed dementia is the most common type of vascular dementia, which is caused by multiple strokes or decreased cerebral blood flow. Multiple strokes may damage some parts of the brain responsible for controlling certain functions. If the part responsible for decision-making and thinking is damaged, symptoms of dementia may appear. So far, patients with cerebrovascular circulation problems can only be controlled with drugs, and maintaining a healthy lifestyle and regular exercise can maintain the patient's physical fitness and slow down the decline; it can also reduce the risk of falls.