視力、聽力減退可能導(dǎo)致認(rèn)知能力下降

Now and then I hear someone (myself included) proclaim “my brain is on overload.” This is not surprising given the myriad complex tasks the brain performs, among them enabling you to learn, plan, remember, communicate, see, hear and smell.

我不時(shí)會(huì)聽到有人(包括我自己)說“我的腦子超負(fù)荷”?？紤]到大腦承擔(dān)的數(shù)不清的復(fù)雜任務(wù)，包括讓你能夠?qū)W習(xí)、規(guī)劃、記憶、交流、看、聽和聞，這不足為奇。

Perhaps also not surprising, a growing number of studies have linked compromised sensory functions like poor vision and hearing to a decline in cognitive abilities. The brain, it seems, can do only so much, and when it must struggle to make sense of the world – from reading the words on a page to understanding the spoken word – it may be less able to perform other important tasks.

或許同樣不足為奇的是，越來(lái)越多的研究把視力和聽力下降等感官功能受損和認(rèn)知能力下降聯(lián)系在了一起。似乎大腦能力有限，當(dāng)它必須掙扎著理解外部世界——從看懂書面文字到理解口頭語(yǔ)言——它進(jìn)行其他重要任務(wù)的能力可能會(huì)減弱。

While a cause-and-effect relationship has yet to be established, evidence is gradually increasing to suggest that uncorrected deficits in vision and hearing can accelerate cognitive decline.

盡管還沒確定兩者之間的因果關(guān)系，但越來(lái)越多的證據(jù)表明，未得到修復(fù)的視力和聽力受損可能會(huì)加劇認(rèn)知能力的下降。

National statistics demonstrate the importance of this relationship. The number of Americans with poor vision, often undetected among older adults, is expected to double by 2050; hearing loss – mostly untreated or undertreated – afflicts nearly two-thirds of adults over 70; both vision and hearing impairment occur in one person in nine age 80 and older (fewer than one in five have neither), and the prevalence of dementia is now doubling every 20 years.

全國(guó)性統(tǒng)計(jì)數(shù)據(jù)顯示出了這種關(guān)系的重要性。到2050年，美國(guó)視力下降的人數(shù)預(yù)計(jì)會(huì)翻倍，而這在上了年紀(jì)的人群中是經(jīng)常未被察覺的一個(gè)問題;聽力受損者在70歲以上的人群中占近三分之二，他們大多未得到治療或治療不充分;80歲及以上的人群中，視力和聽力都下降的比例為九分之一(兩者均未受損的不到五分之一)，癡呆癥的發(fā)病率現(xiàn)在每20年翻一倍。

The latest study, published in August in JAMA Ophthalmology, found that among a representative sample of nearly 3,000 older Americans and a second sample of 30,000 Medicare beneficiaries, poor vision was associated with poor cognition.

8月發(fā)表在《眼科學(xué)紀(jì)要》(JAMA Ophthalmology)上的一項(xiàng)最新研究發(fā)現(xiàn)，在由3000名美國(guó)老年人組成的代表性樣本和3萬(wàn)名聯(lián)邦醫(yī)療保險(xiǎn)(Medicare)的受益者組成的另一份樣本中，視力不良和認(rèn)知能力差存在關(guān)系。

The two data sets used different measurements of cognitive abilities like memory, orientation and planning, and the consistency of their findings suggests that the association between vision impairment and compromised brain function is real, the researchers concluded.

兩個(gè)數(shù)據(jù)集用不同的方法對(duì)記憶力、方向感和規(guī)劃能力等認(rèn)知能力進(jìn)行了衡量，得到了一致的結(jié)果。研究人員斷定，這表明視力受損和大腦功能受損之間的關(guān)聯(lián)是真實(shí)存在的。

The lead author, Dr. Suzann Pershing, ophthalmologist at Stanford University School of Medicine, said that “while this association doesn’t prove vision loss causes cognitive decline, intuitively it makes sense that the less engaged people are with the world, the less cognitive stimulation they receive, and the more likely their cognitive function will decline.”

第一作者、斯坦福大學(xué)醫(yī)學(xué)院(Stanford University School of Medicine)眼科專家蘇珊·珀欣(Suzann Pershing)說，“盡管這種關(guān)聯(lián)無(wú)法證明視力下降導(dǎo)致認(rèn)知能力下降，但它直觀地解釋了人們與外部世界的互動(dòng)越少，他們受到的認(rèn)知刺激越少，認(rèn)知功能下降的可能性越大。”

An earlier study of 625 elderly people at the University of Michigan by Dr. Mary A.M. Rogers and Kenneth M. Langa found that those with poor vision had a 63 percent greater risk of developing dementia over a period of eight and a half years. Those with poor vision who did not visit an ophthalmologist were five times more likely to experience cognitive decline and nine and a half times more likely to develop Alzheimer’s disease.

瑪麗·A·M·羅格斯(Mary A.M. Rogers)和肯尼斯·M·蘭加(Kenneth M. Langa)早前在密歇根大學(xué)(University of Michigan)對(duì)625名老年人進(jìn)行的一項(xiàng)研究發(fā)現(xiàn)，視力下降的人在八年半的時(shí)間里患癡呆癥的風(fēng)險(xiǎn)要高出63%。視力下降卻不看眼科醫(yī)生的人認(rèn)知能力下降的幾率要高出五倍，患阿茲海默癥的可能性高出9.5倍。

“This is not necessarily a one-way relationship,” Dr. Pershing said. “If you improve the vision of people with cognitive impairment, they can function better.”

“這不一定是一種單向關(guān)系，”珀欣說。“如果改善認(rèn)知能力受損者的視力，它們的功能都會(huì)提升。”

Likewise with hearing, where there is stronger evidence that hearing loss can speed cognitive decline. However, it is not yet known whether wearing properly adjusted hearing aids can decrease the risk of dementia or slow its onset. A study sponsored by the National Institute on Aging should show in five years whether using hearing aids can help preserve brain function in people with hearing loss as they age.

聽力也是如此，有更有力的證據(jù)證明，聽力受損會(huì)加速認(rèn)知能力的下降。不過，尚不清楚佩戴合適的助聽器能否降低患癡呆癥的風(fēng)險(xiǎn)或延緩它的發(fā)生。美國(guó)國(guó)家老齡問題研究所(National Institute on Aging)資助的一項(xiàng)研究應(yīng)該能在五年后證明，佩戴助聽器能否幫助保護(hù)那些因年老而出現(xiàn)聽力損傷的人的腦部功能。

Dr. Frank R. Lin, otolaryngologist at the Johns Hopkins Center on Aging and Health, said “the potential impact is huge,” especially now. Companies like Apple and Samsung are expected to soon market hearing aids that cost perhaps $50 to $300 instead of $5,000 a pair, making this assist accessible to many more people. (Already, Dr. Lin said, “Costco has made a huge dent in affordability,” lowering the cost of hearing aids fitted and serviced by well-trained audiologists.)

約翰斯·霍普金斯老齡與健康研究中心(Johns Hopkins Center on Aging and Health)的弗蘭克·R·林博士(Frank R. Lin)表示，“潛在的影響是很大的”，尤其是現(xiàn)在。蘋果(Apple)和三星(Samsung)等公司有望很快推出可能僅需50至300美元的助聽器，讓更多人負(fù)擔(dān)得起這種設(shè)備(林博士說，“好市多[Costco]已經(jīng)極大減輕了人們的經(jīng)濟(jì)負(fù)擔(dān)”，降低了由訓(xùn)練有素的聽力學(xué)家裝配和提供服務(wù)的助聽器的成本)。

Meanwhile, here’s what we already know. A prospective study of 1,984 older adults directed by Dr. Lin found that those who initially had hearing loss were 24 percent more likely than their age-mates with normal hearing to experience cognitive decline within six years.

與此同時(shí)，我們已經(jīng)知道了以下這些情況。林博士主持的一項(xiàng)對(duì)1984名老年人進(jìn)行的前瞻性研究發(fā)現(xiàn)，在實(shí)驗(yàn)之初就有聽力損傷的人在六年內(nèi)出現(xiàn)認(rèn)知能力下降的幾率比聽力正常的同齡人高24%。

Their cognitive abilities declined up to 40 percent faster than others with normal hearing. They had greater problems with brain functions like thinking and memory, developing them on average three years earlier than people their age with normal hearing. And the more severe their hearing loss at the start of the study, the greater their cognitive loss over time.

他們的認(rèn)知能力下降的速度比聽力正常的同齡人快40%。他們比聽力正常的同齡人平均早三年出現(xiàn)思考和記憶等更嚴(yán)重的腦功能問題。在實(shí)驗(yàn)之初聽力受損情況更嚴(yán)重的人，在一段時(shí)間后認(rèn)知能力受損的程度也更嚴(yán)重。

“Older adults with hearing loss face an increased risk of dementia even when you control for diseases like diabetes and high blood pressure,” Dr. Lin said in an interview. “So we think they’re causally related.”

“聽力受損的老年人面臨更高的患癡呆癥風(fēng)險(xiǎn)，盡管排除了糖尿病和高血壓等疾病的影響，”林博士在接受采訪時(shí)說。“所以我們認(rèn)為，它們之間存在因果聯(lián)系。”

He suggested three ways that may explain how poor hearing and dementia are linked. One involves “cognitive load” — when you can’t hear well, the brain receives garbled signals, forcing it to work harder to derive meaning from the message.

他認(rèn)為有三種方法可以解釋為什么聽力不好和癡呆癥有關(guān)。一個(gè)解釋涉及“認(rèn)知負(fù)荷”——你聽不清楚時(shí)，大腦接收的是錯(cuò)亂的信號(hào)，迫使它更努力地工作，試圖弄清那條信息的意思。

Another mechanism may be that people who can’t hear well tend to become socially isolated, which results in diminished cognitive stimulation and cognitive loss.

另一個(gè)機(jī)制可能是那些聽不清的人往往更孤僻，那會(huì)導(dǎo)致認(rèn)知刺激減少，認(rèn)知能力受損。

Perhaps most important is a third possible explanation involving brain structure; hearing loss results in a faster rate of brain atrophy mostly over the hearing portion of the brain, which is also involved in functions like memory, learning and thinking.

可能最重要的是第三種可能的解釋，它與大腦結(jié)構(gòu)有關(guān)。聽力損傷會(huì)導(dǎo)致大腦萎縮速度加快，主要是大腦的聽力部分，而這個(gè)部分也跟記憶、學(xué)習(xí)和思考等功能有關(guān)。

At Washington University in St. Louis, Jonathan Peelle and colleagues have shown through functional M.R.I. studies that even people with mild hearing loss “recruit more of their frontal cortex,” which means that the part of the brain needed for thinking and decision-making is overworked when trying to understand speech.

圣路易斯華盛頓大學(xué)(Washington University)的喬納森·皮爾(Jonathan Peelle)和同事們通過功能性核磁共振研究發(fā)現(xiàn)，即使是那些具有輕微聽力障礙的人“也需要更多的使用自己的額皮質(zhì)”，那就意味著大腦需要用來(lái)進(jìn)行思考和決策的部分因努力理解講話而被過度使用。

“Even in young adults with clinically normal hearing,” Dr. Peelle said, “just a small decline in how well they hear engages more of their frontal cortex.” When hearing loss is advanced, studies have shown that the auditory cortex shrinks, which may diminish the brain’s ability to perform tasks other than hearing, he said.

皮爾博士表示，“即使是那些被臨床判定聽力正常的年輕人，哪怕聽力略微下降，也會(huì)更多地使用額皮質(zhì)。”他還說，多項(xiàng)研究表明，聽力損傷加重后，聽覺皮質(zhì)會(huì)萎縮，那可能會(huì)降低大腦完成聽力之外的其他任務(wù)的能力。

While the cost-effectiveness of regular screening programs for vision and hearing in older adults has yet to be demonstrated, experts strongly recommend periodic exams to pick up correctable problems that may diminish the risk of dementia and would certainly improve quality of life.

雖然老年人定期進(jìn)行視力和聽力篩查的成本效用尚待確認(rèn)，但專家們強(qiáng)烈建議定期進(jìn)行檢查，以便發(fā)現(xiàn)可糾正的問題，從而可能降低患癡呆癥的風(fēng)險(xiǎn)，且無(wú)疑能提高生活質(zhì)量。

The American Academy of Ophthalmology recommends a comprehensive eye exam every two to four years for people aged 40 to 54 with no symptoms or risk factors for vision loss, increasing to every one to three years for those aged 55 to 64, and every year or two thereafter. The exams can help to preserve vision by detecting correctable or treatable problems like glaucoma, cataracts and age-related macular degeneration.

美國(guó)眼科學(xué)會(huì)(American Academy of Ophthalmology)建議40歲至54歲沒有任何視力損傷癥狀或風(fēng)險(xiǎn)的人每二至四年進(jìn)行一次全面眼部檢查，55歲至64歲的人每一至三年檢查一次，之后每一至兩年檢查一次。那些檢查可以幫助保護(hù)視力，因?yàn)橥ㄟ^它們可以查出青光眼、白內(nèi)障以及老年性黃斑變性等可以矯正或治療的問題。

The American Speech-Language-Hearing Association recommends a hearing test “at least every decade through age 50 and every three years thereafter.” As Dr. Lin explained, hearing loss can occur so gradually that people don’t recognize the problem until it is well advanced. Also, there is no harm done in getting tested.

美國(guó)演講語(yǔ)言聽力協(xié)會(huì)(American Speech-Language-Hearing Association)建議“50歲之前至少每十年進(jìn)行一次聽力檢查，之后每三年進(jìn)行一次”。林博士表示，聽力損傷進(jìn)展得十分緩慢，人們只會(huì)在它非常嚴(yán)重時(shí)才會(huì)發(fā)現(xiàn)。而且，檢查一下也沒什么壞處。