柏克莱加州大学研究人员Thaddeus Haight指出，吸二手烟有导致患老年痴呆症和其它痴呆症的危险。这是第一项将精神痴呆症状与二手烟相关联的研究，这篇研究报告将于本周在波士顿举行的美国神经病学会的年会上提出。
研究作者表示，过去的研究显示，吸二手烟与早期心血管疾病和临床心血管疾病有关。但是也有研究显示，脂肪沉滞性动脉硬化症和动脉硬化与痴呆症的危险增加有关。
这项新研究试着探索心血管疾病与痴呆症之间的关系，以及烟草对神经系统的单独和直接作用。除心血管疾病外，还有其它因素可能产生毒害神经的作用，二手烟会透过痴呆症影响神经分化，因此使得痴呆症的机率升高。
研究人员在长期的心血管健康研究中，分析了3602名两组参与者的数据，一组是既无心血管疾病、也无痴呆症的不吸烟者共985人，另一组是吸二手烟平均28年的495人。将两组进行六年的对比分析后显示，吸二手烟逾30年的老年人患痴呆症的比率，比从未吸二手烟的人高30%。
目前研究人员正研究吸烟如何对痴呆症产生直接影响，试着找到二手烟在临床血管疾病过程中的作用。分析数据显示，如果长期吸二手烟并患心血管疾病，将使患痴呆症的危险增加近一倍，若只是长期吸二手烟，患痴呆症的危险则约高三分之一。如果颈动脉异常再加上吸二手烟，患痴呆症的机率则比颈动脉既不异常、也不吸二手烟的人高2.5倍。
（编译/姜欣慧） (资料来源 : Bio.com)
英文原文：
Secondhand Smoke Increases Risk Of Dementia
05/02/07 -- Exposure to secondhand tobacco smoke increases the risk of developing dementia, according to new research. For the study, researchers evaluated 3,602 people age 65 and older in the Cardiovascular Health Study. Of those, 985 people had no cardiovascular disease, no dementia, and were never smokers. A total of 495 people reported their lifetime secondhand smoke exposure, with an average of about 28 years of exposure. Then the researchers evaluated which participants developed dementia over a six-year period.
Based on preliminary results, the study authors found that elderly people with high lifetime exposure to secondhand smoke were approximately 30 percent more likely to develop dementia than those with no lifetime secondhand smoke exposure. High exposure was defined as more than 30 years of exposure to secondhand smoke.
"We are still conducting analyses to control for other factors that may be influencing these results, but this finding potentially implicates lifetime exposure to secondhand tobacco smoke as a risk factor for dementia in older adults," said study author Thaddeus Haight of UC Berkeley.
The study also found that exposure to secondhand smoke resulted in a greater occurrence of dementia for people who had not been diagnosed with cardiovascular disease but who had detectable abnormalities of their carotid arteries, based on carotid ultrasound imaging, compared to those without these underlying abnormalities. These abnormalities included narrower carotid arteries and thicker carotid arterial walls, and serve as indicators of preclinical cardiovascular disease and are risk factors for stroke. People with these underlying conditions and high lifetime exposure to secondhand smoke were nearly two-and-a-half times as likely to develop dementia as those with no secondhand smoke exposure and no indications of carotid artery disease.
"This is one of the first studies to look at the risk of dementia in people who never smoked, but were exposed to secondhand smoke," Haight said. "These results show that secondhand smoke is associated with increased risk of dementia, even in people without known risk factors for dementia related to diagnosed cardiovascular disease."
The study investigators used statistical methods to assess the associated risk of exposure to secondhand smoke independent of its known effects on clinically diagnosed cardiovascular disease.
"The fact that there were more people in this study population who were not diagnosed, but had underlying cardiovascular disease compared to people who were diagnosed points to the health risks associated with lifetime exposure to secondhand tobacco smoke in a potentially wider segment of the elderly population," said Haight.
Haight said the study findings provide additional evidence of the hazards of secondhand smoke and provide additional support for policies that seek to reduce the public's exposure to tobacco smoke.
The findings were presented at the American Academy of Neurology's 59th Annual Meeting in Boston which ran from April 28 to May 5, 2007.
The study was supported by a grant from the Flight Attendant Medical Research Institute, University of California, San Francisco.
Source: American Academy of Neurology
