广播电视英语短句 第 294 课：46个染色体-4

In the early nineteen eighties they lived an average of just twenty-five years. 在19世纪80年代早期，他们平均只能活到25岁。

Today the life expectancy for someone with Down syndrome is sixty years. 如今，对于一些患有唐氏综合症的人来说，其生命预期达到60年。

But with that longer life, people with Down syndrome may have an increased risk for Alzheimer's disease at an early age. 但是，随着拥有更长的生命，患有唐氏综合症的人会有一种逐步增加的风险，那就是从小就罹患老年痴呆症。

An estimated twenty-five percent of those thirty-five and older show signs of the brain-wasting disease. 在一项统计中，35岁及更大年龄的这类人中有25%显示出脑萎缩疾病的征兆。

It slowly destroys memory, thinking and reasoning skills. （这种疾病）它会逐渐破坏记忆，思考以及推理技能。