许多疾病都有特定的原因 - 例如麻疹是由麻疹病毒引起的。虽然目前尚不清楚为什么人们会患上痴呆症，但有许多因素被认为与病情的发展有关。一些是风险因素，而另一些是保护性的。
Many diseases have specific causes - for example a virus causes measles. Although it is not currently understood why people develop dementia, there are many factors which have been suggested to be linked to the development of the condition. Some are risk factors, while others appear to be protective.
Risk factors are characteristics or factors that appear to have some relationship to the development of a disease. If these risk factors are present, there is an increased chance, but not a certainty,that the disease will develop. For example, not everyone who smokes develops heart disease and not everyone with heart disease has been a smoker. However,smoking is a strong risk factor for heart disease.
Risk factors can include family background or exposures to a substance or product. Going back to the example of smoking: aperson who smokes has a greater risk of developing heart disease than someone who does not smoke. Some risk factors can be modified, for example lowering blood pressure reduces the risk of a stroke; other risk factors cannot be modified, for example age or family history.
Age and a strong family history of dementia are risk factors with a strong link to dementia. Excessive alcohol consumption,head injury, and risk factors for heart disease such as high blood pressure,diabetes, smoking and being overweight also seem to increase the risk of getting dementia.
How can I reduce my risk?
There is no cure for dementia but keeping active, eating well and engaging in social activities all promote good brain health, and may reduce your risk of developing the disease. Keeping your heart healthy, including by avoiding smoking and excessive alcohol consumption, can also lower your risk of dementia, and other diseases too.
It seems that people who keep their brains active may be at less risk of developing dementia. Reading, engaging in a hobby such as playing bridge or chess, or doing crosswords and word puzzles may help to reduce risk. You do not need to be highly educated to lower your risk:research suggests that those who speak multiple languages, or who play musical instruments may also be at a lower risk of dementia.