重度吸煙成倍增加得老年癡呆的幾率（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."

美國科學家跟蹤調查了20,000名中年男女，其年齡為50—60歲。受訪者還接受老年癡呆症篩查。研究期限為1978—1985年。

新研究結果發現，在平均23年的跟蹤調查期間，5367人(占25.4%)確診患有老年癡呆症，其中416人為血管性老年癡呆症，1136人為早老性癡呆症。與從不吸煙者和戒煙者相比，每天至少抽煙兩包的人罹患早老性癡呆症的危險增加157%，血管性癡呆症危險增加172%。然而，與從不吸煙者相比，戒煙者和少量吸煙者(每天不到半包)的老年癡呆症危險並沒有增加。研究還發現，“過量吸煙者增加老年癡呆症危險”這一結論，既不分男女，又適用於所有種族。

新研究負責人，來自加利福尼亞的凱撒醫學集團的蕾切爾·惠特默博士表示，新研究發現，大腦對長期過量吸煙起不到免疫作用。吸煙會通過影響血壓，增加血凝因子進而危及血管係統。血管健康問題是老年癡呆症的一大致病風險因素。

研究人員表示，研究業已證實，吸煙是導致中風的一大危險因素，而吸煙增加血管性癡呆危險也具有類似的機理。吸煙會進一步加重氧化壓力和炎症——導致早老性癡呆的兩大關鍵因素。研究報告稱，吸煙也可能會通過血管和神經性退化的途徑加速老年癡呆症的形成。

惠特默博士表示，這項新研究以大規模多種族參試者為對象，首次量化了吸煙增加老年癡呆症的長期危險性。