日前，一项新研究指出，在乡村地区出生并成长起来的人，晚年患阿尔茨海默氏症的几率比生活在城市里的人要高两倍多。研究人员将相关研究成果发表在《国际流行病学期刊》（International Journal of Epidemiology）上。
虽然引起这一趋势的原因尚不清楚，但科学家表示，获得卫生保健的情况，以及暴露于某些特殊物质等因素，可能在其中扮演了重要角色。
在英国，阿尔茨海默氏症影响了大约80万人的健康，并且随着人口老龄化，患者数量到2050年还将翻一番。
爱丁堡大学的一组研究人员调查了过去数十年中发表的51篇学术论文，分析了其中包含的来自全世界的12580人的医疗报告，结果发现，总体来说，痴呆症在农村和城市居民中的发病率存在的差异并不大，但是，阿尔茨海默氏症的发病率却有着显著的不同。
研究人员强调，两组人群间差异的下降可能会与生活在城市里的各种福利有联系，而非与乡村中的有害因素有关。但是，要找出具体的原因还需要进一步详细地研究，不过，卫生保健体系、社会经济学因素、未知事物的影响等因素可能会起到一定作用。
英国阿尔茨海默氏症研究专家Simon Ridley则表示，该研究数据显示了乡村生活和阿尔茨海默氏症发病几率及普遍性之间的联系，但是，这些复杂的证据并不足以引起人潮涌入城市。（生物谷Bioon.com）
doi:10.1093/ije/dys103
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Geographical variation in dementia: systematic review with meta-analysis
Tom C Russ1,2,3,*, G David Batty4, Gena F Hearnshaw5, Candida Fenton6 and John M Starr
Background Geographical variation in dementia prevalence and incidence may indicate important socio-environmental contributions to dementia aetiology. However, previous comparisons have been hampered by combining studies with different methodologies. This review systematically collates and synthesizes studies examining geographical variation in the prevalence and incidence of dementia based on comparisons of studies using identical methodologies. Methods Papers were identified by a comprehensive electronic search of relevant databases, scrutinising the reference sections of identified publications, contacting experts in the field and re-examining papers already known to us. Identified articles were independently reviewed against inclusion/exclusion criteria and considered according to geographical scale. Rural/urban comparisons were meta-analysed. Results Twelve thousand five hundred and eighty records were reviewed and 51 articles were included. Dementia prevalence and incidence varies at a number of scales from the national down to small areas, including some evidence of an effect of rural living [prevalence odds ratio (OR)?=?1.11, 90% confidence interval (CI) 0.79–1.57; incidence OR?=?1.20, 90% CI 0.84–1.71]. However, this association of rurality was stronger for Alzheimer disease, particularly when early life rural living was captured (prevalence OR?=?2.22, 90% CI 1.19–4.16; incidence OR?=?1.64, 90% CI 1.08–2.50). Conclusions There is evidence of geographical variation in rates of dementia in affluent countries at a variety of geographical scales. Rural living is associated with an increased risk of Alzheimer disease, and there is a suggestion that early life rural living further increases this risk. However, the fact that few studies have been conducted in resource-poor countries limits conclusions.
