据新英格兰医学杂志2016年2月11日报告，美国著名的“Framingham 研究”跟踪了5千2百多人40年后发现，老年痴呆发病率逐年降低，累积减少44%之多。这个“铁证”（robust evidence ），再加上2005年的一项类似研究报告，让医学界着实兴奋起来，可问题是为什么呢？药物科学家不敢声明“有功”，因为到目前为止还没有发现一个公认抗老年痴呆的有效药；心脏科医生尝试“领功”，因为血管性痴呆有减少，可是与血管病无关的阿尔茨海默痴呆同样减少。也就是说，尽管投入巨额研究经费和努力，没发现什么灵丹妙药，老年痴呆自己减少了！这个深奥的现象或许能给医学界点启示，现在实行的“疾病主攻战略”是否有一定局限性，常常是“按了葫芦起了瓢”，刚降低了一个疾病，另外一又高发起来。而人体的健康和各种疾病之间很可能存在一种“平衡状态”，类似中医所说的“天人合一”和“整体观”，医疗要做的不仅是抗病，还要帮助患者提高身体素质和生活质量。这里还要指出研究中发现的一个细节，老年痴呆的减少只发生在有高中以上文化的人，可见老师也有功。 （李永明）
Incidence of Dementia over Three Decades in the Framingham Heart Study
February 11, 2016
N Engl J Med 2016; 374:523-532
Participants in the Framingham Heart Study have been under surveillance for incident dementia since 1975. In this analysis, which included 5205 persons 60 years of age or older, we used Cox proportional-hazards models adjusted for age and sex to determine the 5-year incidence of dementia during each of four epochs. We also explored the interactions between epoch and age, sex, apolipoprotein E ε4 status, and educational level, and we examined the effects of these interactions, as well as the effects of vascular risk factors and cardiovascular disease, on temporal trends.
The 5-year age- and sex-adjusted cumulative hazard rates for dementia were 3.6 per 100 persons during the first epoch (late 1970s and early 1980s), 2.8 per 100 persons during the second epoch (late 1980s and early 1990s), 2.2 per 100 persons during the third epoch (late 1990s and early 2000s), and 2.0 per 100 persons during the fourth epoch (late 2000s and early 2010s). Relative to the incidence during the first epoch, the incidence declined by 22%, 38%, and 44% during the second, third, and fourth epochs, respectively. This risk reduction was observed only among persons who had at least a high school diploma (hazard ratio, 0.77; 95% confidence interval, 0.67 to 0.88). The prevalence of most vascular risk factors (except obesity and diabetes) and the risk of dementia associated with stroke, atrial fibrillation, or heart failure have decreased over time, but none of these trends completely explain the decrease in the incidence of dementia.
Among participants in the Framingham Heart Study, the incidence of dementia has declined over the course of three decades. The factors contributing to this decline have not been completely identified. (Funded by NIH)