The World Health Organization (WHO) defines dementia as an illness marked by a decline in a person's ability to think, reason and understand " beyond what might be expected from normal aging" .

世界卫生组织（WHO）将痴呆症定义为一种疾病，其特征是患者的思考、推理和理解能力以" 超出正常老化" 的速度退化。

Results showed that the cyclists did not experience body changes usually equated with a normal aging process. For example, they did not lose muscle mass or strength. Also, their body fat and cholesterol levels did not increase with age.

结果表明，骑自行车的人没有经历身体变化，通常等同于正常的老化过程。例如，他们的肌肉质量或力量没有减小。此外，他们的身体脂肪和胆固醇指标并没有随着年龄增加而上升。