研究發現老年痴呆症發病率下降
2013年07月17日
Chris Steele-Perkins/Magnum
一項最近研究發現在，在英格蘭和威爾士，65歲及以上人群中的痴呆症患者比例正在下降。
一項最新研究發現，在英格蘭和威爾士，65歲及以上人群中痴呆症患者的比例在過去二十年下降了25%，從8.3%下降到了6.2%。研究人員稱，這種趨勢可能正發生在所有發達國家，並且可能對家庭和社會帶來重要的社會和經濟影響。
前不久，在丹麥做的另一項研究發現，在2010年接受心智
能力標準測試的90多歲的人的得分，遠遠好於十年前的那些90多歲的人。在2010年接受測試的人中，將近四分之一的得分達到了最高水平，這個比例是
1998年那次測試的兩倍。在調查對象當中，心智能力嚴重受損者的比例從22%降到了17%。
英國的研究和丹麥的研究分別於本周二和上周發表在《柳葉刀》(The Lancet)上。這兩項研究緩和了倡導組織和一些公共健康官員的警告，這些組織和官員預測，痴呆症患者的人數以及照顧這些患者的成本將會快速增加。這些預測的假定前提是患痴呆症的幾率不會改變。
然而，研究老齡化問題的專家稱，這兩項研究還證實了他們有
所懷疑卻難以證明的東西：隨着人們變得更健康，接受的教育更好，痴呆症患者比例將會下降，精神敏銳度也會得到改善。在受教育程度更好和控制血壓及膽固醇的
人中間，痴呆症發病率較低，可能是因為部分痴呆症是由短暫性腦缺血發作和其他血管損傷導致的。因此，鑒於人們更好地控制了心血管風險因素，並接受了更多的
教育，患痴呆症的風險有所降低也是順理成章的事情。之前已經有六項研究暗示這一比例正在下降，但這些研究存在一些瑕疵，導致一些人質疑它們的結論。
研究人員稱，這兩項最新研究是迄今為止最有力、最可靠的證據，證明那些研究的預感是對的。美國痴呆症研究的主要出資機構國家老齡化研究所(National Institute on Aging)痴呆症流行病學專家達拉斯·安德森(Dallas Anderson)表示，最新研究「很嚴密，可以作為有力的證據」。他補充說，他估計美國也出現了同樣的趨勢，但必須通過研究才能確證。
杜克大學(Duke University)的阿耳茨海默氏征研究員P·穆拉利·多雷斯瓦米(P. Murali Doraiswamy)博士沒有參與這項新研究，但他表示，「這是一個好消息」，意味着關於每一代都有相同的痴呆症風險的普遍假定是站不住腳的。
在關於阿耳茨海默氏征和痴呆症的壞消息不絕於耳之際，新研
究給出了希望。治療阿耳茨海默氏征的一些主要臨床藥物試驗已經失敗。基於痴呆症患病比例將維持穩定的假定，蘭德公司(RAND
Corporation)最近的一項分析得出結論稱，隨着嬰兒潮一代的老去，未來30年里，患有痴呆症的人口數量將會翻番，照顧這些病人的成本也將翻番。
不過，此次分析的主要作者、蘭德公司的首要資深研究員邁克爾·D·赫德(Michael D.
Hurd)在一次採訪中說，如果在英國發現的痴呆症患病比例下降的狀況也適用於美國的話，那他對這種病的未來病例和成本的預測就不能算數了。
荷蘭的內梅亨大學奈美恩醫學院(Radboud
University Nijmegen Medical Center)博士馬塞爾·奧爾德·里克爾特(Marcel Olde
Rikkert)為丹麥的研究撰寫了一篇隨文社評，他說，老年人患上痴呆症風險的預測「急需重設」。
不過，倡導組織阿耳茨海默氏征協會(Alzheimer』s Association)的醫學和科學關係副會長瑪麗亞·卡里略(Maria Carrillo)並不確定這種趨勢是真的，也不確定美國會出現這種趨勢。
評估痴呆病的研究不僅針對阿耳茨海默氏征，也針對其他可能引發腦功能退化的病況。國家老齡化研究所行為與社會研究分部主管理乍得·蘇茲曼(Richard Suzman)說，新研究無法告訴人們，阿耳茨海默氏征是正在變得更為普遍，還是有所收斂。
Dementia Rate Is Found to Drop Sharply, as Forecast
July 17, 2013
A new study has found that dementia rates among
people 65 and older in England and Wales have plummeted by 25 percent
over the past two decades, to 6.2 percent from 8.3 percent, a trend that
researchers say is probably occurring across developed countries and
that could have major social and economic implications for families and
societies.
Another recent study,
conducted in Denmark, found that people in their 90s who were given a
standard test of mental ability in 2010 scored substantially better than
people who had reached their 90s a decade earlier. Nearly one-quarter
of those assessed in 2010 scored at the highest level, a rate twice that
of those tested in 1998. The percentage of subjects severely impaired
fell to 17 percent from 22 percent.
The British study, published on Tuesday in The
Lancet, and the Danish one, which was released last week, also in The
Lancet, soften alarms sounded by advocacy groups and some public health
officials who have forecast a rapid rise in the number of people with
dementia, as well as in the costs of caring for them. The projections
assumed the odds of getting dementia would be unchanged.
Yet experts on aging said
the studies also confirmed something they had suspected but had had
difficulty proving: that dementia rates would fall and mental acuity
improve as the population grew healthier and better educated. The
incidence of dementia is lower among those better educated, as well as
among those who control their blood pressure and cholesterol, possibly
because some dementia is caused by ministrokes and other vascular
damage. So as populations controlled cardiovascular risk factors better
and had more years of schooling, it made sense that the risk of dementia
might decrease. A half-dozen previous studies had hinted that the rate
was falling, but they had flaws that led some to doubt the conclusions.
Researchers said the two
new studies were the strongest, most credible evidence yet that their
hunch had been right. Dallas Anderson, an expert on the epidemiology of
dementia at the National Institute on Aging,
the principal financer of dementia research in the United States, said
the new studies were “rigorous and are strong evidence.” He added that
he expected that the same trends were occurring in the United States but
that studies were necessary to confirm them.
“It’s terrific news,” said
Dr. P. Murali Doraiswamy, an Alzheimer’s researcher at Duke University,
who was not involved in the new studies. It means, he said, that the
common assumption that every successive generation will have the same
risk for dementia does not hold true.
The new studies offer hope
amid a cascade of bad news about Alzheimer’s disease and dementia. Major
clinical trials of drugs to treat Alzheimer’s have failed. And a recent
analysis
by the RAND Corporation — based on an assumption that dementia rates
would remain steady — concluded that the number of people with dementia
would double in the next 30 years as the baby boom generation aged, as
would the costs of caring for them. But its lead author, Michael D.
Hurd, a principal senior researcher at RAND, said in an interview that
his projections of future cases and costs could be off if the falling
dementia rates found in Britain held true in the United States.
Dr. Marcel Olde Rikkert of
Radboud University Nijmegen Medical Center in the Netherlands, who wrote
an editorial to accompany the Danish study, said estimates of the risk
of dementia in older people “urgently need a reset.”
But Maria Carrillo, vice
president of medical and scientific relations at the Alzheimer’s
Association, an advocacy group, was not convinced that the trends were
real or that they held for the United States.
The studies assessed
dementia, which includes Alzheimer’s disease but also other conditions
that can make mental functioning deteriorate. Richard Suzman, the
director of the division of behavioral and social research at the
National Institute on Aging, said it was not possible to know from the
new studies whether Alzheimer’s was becoming more or less prevalent.
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