重度吸烟成倍增加得老年痴呆的几率（Heavy Smoking Doubles Alzheimer's Risk）

Heavy Smoking Linked to Alzheimer's, Dementia Risk

Looking to lower your odds of developing Alzheimer's disease and dementia? Stop smoking if you light up.

New research finds that heavy smoking during middle age more than doubles a person's risk of these brain disorders later in life. People who smoke two packs of cigarettes a day increase their risk of Alzheimer's by 157 percent, according to a study published Monday in the Archives of Internal Medicine. And they have a 172 percent higher risk of developing vascular dementia, the second-most-common form of dementia after Alzheimer's.

Researchers analyzed the medical records of more than 20,000 people who were followed for 23 years starting in their 50s and 60s to see who would develop these conditions as they hit their twilight years The heightened risk may be due to smoking causing tissue inflammation, which plays a role in Alzheimer's, the study authors say.

"We've known for some time that smoking is bad for your respective health," research scientist Rachel Whitmer told Reuters. "This really adds to our understanding that the brain is also susceptible."

美国科学家跟踪调查了20,000名中年男女，其年龄为50—60岁。受访者还接受老年痴呆症筛查。研究期限为1978—1985年。

新研究结果发现，在平均23年的跟踪调查期间，5367人(占25.4%)确诊患有老年痴呆症，其中416人为血管性老年痴呆症，1136人为早老性痴呆症。与从不吸烟者和戒烟者相比，每天至少抽烟两包的人罹患早老性痴呆症的危险增加157%，血管性痴呆症危险增加172%。然而，与从不吸烟者相比，戒烟者和少量吸烟者(每天不到半包)的老年痴呆症危险并没有增加。研究还发现，“过量吸烟者增加老年痴呆症危险”这一结论，既不分男女，又适用于所有种族。

新研究负责人，来自加利福尼亚的凯撒医学集团的蕾切尔·惠特默博士表示，新研究发现，大脑对长期过量吸烟起不到免疫作用。吸烟会通过影响血压，增加血凝因子进而危及血管系统。血管健康问题是老年痴呆症的一大致病风险因素。

研究人员表示，研究业已证实，吸烟是导致中风的一大危险因素，而吸烟增加血管性痴呆危险也具有类似的机理。吸烟会进一步加重氧化压力和炎症——导致早老性痴呆的两大关键因素。研究报告称，吸烟也可能会通过血管和神经性退化的途径加速老年痴呆症的形成。

惠特默博士表示，这项新研究以大规模多种族参试者为对象，首次量化了吸烟增加老年痴呆症的长期危险性。