People who smoked two packs of cigarettes or more a day at midlife were more than twice as likely as nonsmokers to develop dementia and dementia subtypes such as Alzheimer’s disease, according to a report published online Oct. 25 in the Archives of Internal Medicine.

The association between midlife smoking and dementia 2-3 decades later remained robust after the data were adjusted to account for several confounding factors, including stroke. Therefore, smoking “seems to have some independent effect on vascular dementia, beyond acceleration of cerebrovascular disease,” said Dr. Minna Rusanen of the department of neurology at the University of Eastern Finland, Kuopio, and her associates.

Very few studies have addressed the long-term cerebrovascular consequences of smoking in middle age, and those that have done so had small sample sizes of predominantly white subjects, the investigators noted (Arch. Intern. Med. 2010 [doi:10.1001/archinternmed.2010.393]).

Dr. Rusanen and her colleagues studied the issue using data from a large, multiethnic cohort of more than 33,000 people who were members of the Kaiser Permanente Medical Care Program of Northern California. The study subjects took part in the Multiphasic Health Checkup and were first assessed at enrollment between 1978 and 1985, when they were aged 50-60 years. For the analysis, the medical records of 21,123 people who were still living and in the health plan at follow-up in 1994 were reviewed for dementia diagnoses.

A total of 5,367 people (25%) were diagnosed by neurologists, neuropsychologists, or internists as having dementia, including 1,136 cases of Alzheimer’s disease and 416 cases of vascular dementia.

After researchers adjusted for age, sex and certain cardiovascular risk factors, they found that people who smoked two or more packs per day at midlife were more than twice as likely as nonsmokers to develop dementia (risk-adjusted hazard ratio, 2.14), Alzheimer’s disease (HR, 2.57), or vascular dementia (HR, 2.72) 20-30 years later.

The association between smoking and dementia risk was analyzed separately for people who had stroke, compared with those who did not have stroke, because stroke is a robust predictor of dementia and is highly associated with smoking. Midlife smoking remained a robust independent predictor of dementia and dementia subtypes in that subanalysis, the investigators said. Compared with nonsmokers who had a stroke, those who had smoked two or more packs per day and had a stroke were 1.83 times more likely to develop dementia.

The link between midlife smoking and later dementia also remained robust when the data were adjusted for patient race, ethnicity, and gender. “Based on the present results, we can postulate that the deleterious effects of smoking on risk of dementia seem to be the same for both sexes and across different ethnic groups,” Dr. Rusanen and her associates said.

The study was supported by the National Graduate School of Clinical Investigation, Kuopio University Hospital, the Juho Vainio Foundation, the Maire Taponen Foundation, Kaiser Permanente Community Benefits, Finland’s National Institute for Health and Welfare, and the Academy of Finland. One of Dr. Rusanen’s associates reported ties to Elan Corp., Pfizer, Janssen, and Novartis.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

东芬兰大学神经病学系Minna Rusanen博士10月25日在《内科学年鉴》在线发表的一篇报告称，中年人每日吸烟2包或以上的人群发生痴呆症和痴呆症亚型如阿尔茨海默病的风险是非吸烟者的2倍以上 (Arch. Intern. Med. 2010 [doi:10.1001/archinternmed.2010.393]).

 

此前，有关中年人吸烟对脑血管长期影响的研究很少，研究对象以白色人种为主且样本量很小。为此，研究者进行了大规模、多种族队列研究，以考察中年人吸烟对后来痴呆症发生风险的影响。

 

研究对象为1978～1985年入组参与健康调查项目的人群，年龄50～60岁。研究者查阅了目前仍存活的21,123例自1994年开始接受随访人群的病历，以统计痴呆症的发生情况。

 

结果显示，5,367例(25%)随访者被诊断为痴呆症，其中包括1,136例阿尔茨海默病和416例血管性痴呆。研究者调整年龄、性别和肯定的心血管风险因素后发现，每天吸烟2包或以上的受访者20～30年后发生痴呆症(风险因素调整后风险比为2.14)、阿尔茨海默病(风险比为2.57)或血管性痴呆(风险比为2.72)的风险是非吸烟者的2倍以上。每天吸烟2包或以上且发生卒中者发生痴呆症的风险高出非吸烟卒中者1.83倍。此外，调整种族、民族以及性别因素后，中年吸烟与此后发生痴呆症风险仍呈现高度相关。

 

研究表明，中年吸烟与20~30年后痴呆症发生风险高度相关，中年吸烟是痴呆症及其亚型的显著独立预测因素，并且吸烟对不同性别和不同种族人群发生痴呆症风险的有害影响相似。

 

该研究接受多家医学机构和基金会资助。

 

爱思唯尔  版权所有