mlp0515

作者：Deborah Brauser  
出處：WebMD醫學新聞

　　January 28, 2010 — 根據發表於1月25日內科醫學誌(Archives of Internal Medicine)的兩篇新研究，參與持續的運動計畫可以減少55歲以上者的認知衰退。
　　
　　在德國的一篇世代研究中，研究者發現，適度或高度運動與55歲以上年長者發生認知不佳的風險降低有關。
　　
　　另一篇隨機控制研究則是顯示，持續的訓練計畫改善了加拿大65至75歲女性之注意力與解決衝突能力等認知技能。
　　
　　德國慕尼黑科技大學精神與心理治療學系助理教授Thorleif Etgen醫師等人寫道，我們對一大群年長對象進行的人口基礎前瞻研究發現，缺乏體能活動和兩年後發生認知不全有顯著關係。
　　
　　Etgen醫師在Medscape Neurology的訪問中表示，他對於研究發現的內容感到驚訝。體能活動減少了將近半數的偶發性認知不全發生，我們也對適度活動可以和高度活動獲得幾乎相同的效果感到驚訝。
　　
　　他指出，老年人口持續增加，因此，認知衰退與失智的發生率也呈現成長，極需有用且便宜的介入方式來延緩這些衰退。
　　
　　【研究顯示減少不佳情形】
　　Etgen醫師與其團隊在他們的研究中，檢視了於2001至2003年招募自「the Intervention Projecton Cerebrovascular Diseases and Dementia in the Community ofEbersberg, Bavaria study (INVADE)」研究的3,903名病患，每3個月追蹤一次、為期兩年。所有病患都完成一個有6項的認知不全檢測以及一份問卷，根據活動程度將他們分成以下組別：沒有運動組(n = 584人)、適度運動組(n = 1523人)以及高度運動組(n = 1796)。
　　
　　適度運動定義為每週進行費力運動(包括走路、徒步旅行、騎腳踏車與游泳)少於3天，高度運動定義為每週進行這些運動3天或以上。
　　
　　Etgen醫師表示，我們希望確定體能活動的一些保護效果，因為以前的研究多數聚焦在失智，我們對這部份INVADE研究的目標是，進一步探索認知不全(失智的早期型式)和體能活動之間的關聯。
　　
　　開始時，418名研究對象(10.7%)有認知不全，其中，無運動組有21.4%、適度運動組和高度運動組分別有10.5% 和7.3%。
　　
　　兩年結束時，研究者發現，有另外207名病患(5.9%)發生認知不全，無運動組發生新的認知不全的比率為13.9%，適度運動組和高度運動組都顯著較低，分別只有6.7% (勝算比[OR]為0.57；95%信心區間[CI]為0.37 – 0.87；P = .01)與5.1% (OR，0.54；95% CI，0.35 – 0.83；P = .005)。
　　
　　校正年紀、性別、憂鬱、慢性腎臟病與心血管風險因素之後，前述關聯依舊相當顯著。
　　
　　Etgen醫師表示，希望大家記住的是，保持活動。醫師們應更積極要求他們的病患從事體能活動，並提醒他們的年長病患進行某種規律的體能活動。
　　
　　【肌力訓練改善認知技能】
　　在第二篇研究中，研究者試圖檢視年長女性的肌力訓練與改善認知之間的關聯。
　　
　　加拿大英屬哥倫比亞物理治療系助理教授、溫哥華綜合醫院髖骨健康與活動力研究中心研究員Teresa Liu-Ambrose博士寫道，就我們所知，迄今沒有研究檢視有認知助益的最少量肌力訓練頻率。
　　
　　Liu-Ambrose博士向Medscape Neurology表示，我們對於肌力訓練特別有興趣，因為與其他訓練相比，它有多種助益，因為它與預防跌倒和骨折有關。我們知道，這對骨骼健康、預防肌肉流失、幫助加強強度等有效果，不過，多數有關運動對認知有幫助的研究僅著眼於有氧訓練。
　　
　　她的團隊於2007年5月至2008年4月間納入了155名年紀在65至75歲的婦女，將她們隨機分派接受每週一次(n = 54人)或每週兩次(n = 52人)的肌力訓練課程，或者每週兩次的平衡與增強訓練課程(對照組、n = 49人)。
　　
　　所有病患都進行關於選擇性注意力和衝突解決力的「叫色執行測驗」，以及路徑描繪測驗，另外也測量步態速度與全腦容量。
　　
　　一年後的結果顯示，相較於對照組，兩種肌力訓練組病患的叫色測驗都有顯著的改善(P≦.03)，此外，研究作者們寫道，每週一次以及每週兩次肌力訓練組的任務進行改善率分別是12.6%和10.9%，平衡與增強訓練課程組則是惡化了0.5%。
　　
　　不過，令人驚訝的是，兩種肌力訓練組也顯示全腦容量比對照組顯著減少(P≦.03)。
　　
　　Liu-Ambrose博士表示，這個減少是令人驚訝的發現，因為那通常與不佳的認知功能有關，我們目前針對更多資料來評估灰質和白質容量。
　　
　　最後，增加步態速度與促進選擇性注意力和衝突解決能力有顯著關聯(P < .01)。
　　
　　Liu-Ambrose博士解釋，這個發現與臨床相當有關，因為走路速度是一個人的一般健康狀態與預測發病的一項重要指標。
　　
　　研究作者們寫道，整體而言，這些結果有重要的臨床意義，不過，因為研究的病患族群之故，這個發現無法推論到男性或者其他年紀的女性。此外，他們指出，是在訓練後12個月才發現認知方面的助益，在6個月、試驗中期時並未發現。
　　
　　Liu-Ambrose博士解釋，這可能是因為肌力訓練組有許多的動作學習與教育項目，特別是最初的2-3個月時，因此，在教導、學習這些技巧與熟悉它們之間有一個時間差。
　　
　　她表示，希望大家從這個研究記住的是，應更推廣肌力訓練，目前在臨床促進運動，但是我認為應更廣泛，例如「走更多路」，有許多新證據顯示，肌力訓練不只和有氧訓練有類似的助益，還有一些特別的好處，它也是活動力有限之年長者的選項之一。
　　
　　Ambrose博士報告指出，她的團隊希望繼續追蹤這群病患，且在新試驗中期時比較有氧訓練以及肌力訓練和平衡與增強訓練等，對於有風險的病患族群的效果。
　　
　　【有希望的證據】
　　佛羅里達大學老化與老年醫學研究系主任、老化研究中心主任Marco Pahor教授向Medscape Neurology表示，這兩篇研究都提供了「任何型式的體能活動都可望改善認知功能」的證據。Pahor教授與他的同事、位於北卡羅來納Winston-Salem的Wake Forest大學醫學中心老年醫學小組主任Jeff Williamson醫師一起撰寫編輯評論。
　　
　　Pahor教授表示，不過，這兩篇研究都有一些限制，Etgen醫師的研究是一個觀察型研究，無法提供因果關係的明確證據。加拿大的這篇研究是一個隨機控制試驗，但是樣本數有限，且只有12個月，時間太短而無法評估對於認知的效果。
　　
　　他結論表示，希望大家記住的是，這兩篇研究提供了更多證據證明，體能活動對於促進年長成人的健康是很重要的因素，這兩篇研究都相當令人信服，也建立了進行更大型多中心試驗的基礎。
　　
　　Allgemeine Orskrankenkasse (巴伐利亞邦的一個保險公司)資助第一篇研究。溫哥華基金會、加拿大自然科學與工程研究委員會、Michael Smith健康研究基金會、加拿大研發基金會的新機會資金等資助第二篇研究。研究者和編輯都宣告沒有任何相關的財務關係。


Exercise May Improve Cognitive Skills in Older Population

By Deborah Brauser
Medscape Medical News

January 28, 2010 — Participating in a sustained exercise program may decrease cognitive decline in patients older than 55 years, according to results from 2 new studies published in the January 25 issue of the Archives of Internal Medicine.

In a cohort study from Germany, investigators found that moderate or high physical activity was associated with a lower risk of developing cognitive impairment in patients older than 55 years.

The second randomized controlled study showed that resistance training programs improved the cognitive skills of attention and conflict resolution in women between the ages of 65 and 75 years in Canada.

"Our population-based prospective study of a large cohort of elderly subjects found that lack of physical activity yielded a significant association with incident cognitive impairment after 2 years," write Thorleif Etgen, MD, assistant professor in the Department of Psychiatry and Psychotherapy at the Technische Universitat in Munich, Germany, and colleagues.

In an interview with Medscape Neurology, Dr. Etgen said that he was amazed at the extent of the findings. "Physical activity cut in half the odds of developing incident cognitive impairment. We were also surprised that moderate physical activity had nearly the same effect as high physical activity."

"The population of older adults is expanding, and with this, the incidence of cognitive decline and dementia is growing," he added. "There is a high demand for powerful and inexpensive methods of preventing or delaying these declines."

Study Shows Decreased Impairment

In their study, Dr. Etgen and his team examined a cohort of 3903 patients enrolled in the Intervention Projecton Cerebrovascular Diseases and Dementia in the Community ofEbersberg, Bavaria study (INVADE) between 2001 and 2003 and followed up every 3 months for 2 years. All patients had filled out 6-item Cognitive Impairment Tests and a questionnaire that divided them by activity levels: none (n = 584), moderate (n = 1523), and high (n = 1796).

Moderate activity was defined as strenuous activities (including walking, hiking, bicycling, and swimming) performed fewer than 3 days a week, whereas high activity was defined as 3 or more times a week of participation.

"We were hoping to establish some protective effect of physical activity," said Dr. Etgen. "As most studies in the past focused on dementia, our aim of this part of the INVADE study was to further explore the association between cognitive impairment (as an early form of dementia) and physical activity."

At baseline, 418 participants (10.7%) had cognitive impairment. Of these, 21.4% were in the no activity group compared with 10.5% and 7.3% in the moderate and high activity groups, respectively.

At the end of 2 years, the investigators found that 207 additional patients (5.9%) had developed impairment. Although the incidence of new cognitive impairment among those with no physical activity was 13.9%, the incidence was significantly lower at only 6.7% (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.37 – 0.87; P = .01) and 5.1% (OR, 0.54; 95% CI, 0.35 – 0.83; P = .005) in those who underwent moderate and high activity, respectively.

This association remained statistically significant even after adjusting for age, sex, depression, chronic kidney disease, and cardiovascular risk factors.

"The take-home message is: keep on moving," said Dr. Etgen. "Clinicians should more actively ask their patients about their physical activity and alert their elder patients to perform some sort of regular physical activity."

Resistance Training Improves Cognitive Skills

In the second study, investigators sought to examine the association between resistance training and improved cognition in older women.

"To our knowledge, no study to date has examined the minimum frequency of resistance training required for cognitive benefits," write Teresa Liu-Ambrose, PhD, PT, researcher at the Center for Hip Health and Mobility at Vancouver General Hospital and assistant professor at the Department of Physical Therapy at the University of British Columbia in Canada, and colleagues.

"We were interested in resistance training specifically because it has multiple benefits over other training as it relates to falls and fracture prevention," added Dr. Liu-Ambrose to Medscape Neurology. "We know that it benefits bone health, prevents muscle loss, and helps strengthen mass. However, most studies looking at the benefits of exercise for cognition have focused on aerobic training."

Her team enrolled 155 women between the ages of 65 and 75 years and randomized them to undergo either once-weekly (n = 54) or twice-weekly (n = 52) resistance training classes or twice-weekly balance and tone training classes (control group, n = 49) between May 2007 and April 2008.

All patients took the Stroop executive test on selective attention and conflict resolution and Trail Making Tests. Gait speed and whole brain volume were also measured.

Results at the end of 1 year showed that the patients in both of the resistance training groups had significantly improved scores on the Stroop test compared with the control group patients (P ? .03). In addition, "task performance improved by 12.6% and 10.9% in the once-weekly and twice-weekly resistance training groups, respectively. It deteriorated by 0.5% in the balance and tone group," write the study authors.

However, surprisingly, both resistance training groups also showed significant reductions in whole-brain volume compared with the control group (P < .03).

"This reduction was a surprising finding because that's usually associated with poor cognitive function. We are currently looking at more data to specifically assess grey and white matter volume," said Dr. Liu-Ambrose.

Finally, enhanced selective attention and conflict resolution were significantly associated with increased gait speed (P < .01).

"This finding was quite clinically relevant because walking speed is a big indicator of a person's general well-being and also a predictor of mortality," explained Dr. Liu-Ambrose.

Overall, "the results have important clinical implications," write the study authors. However, because of the patient population studied, "the findings may not generalize to men or to women of other ages."

In addition, they note that the cognitive benefits were found after 12 months of training but not at the 6-month trial midpoint.

"This could be because there was a lot of motor learning and motor teaching in terms of resistance training for this group, especially for the first 2 to 3 months of this study," explained Dr. Liu-Ambrose. "So there was a lag time between teaching the technique and them becoming comfortable with it."

She said that her takeaway from this study is that resistance training should be more widely promoted. "I think that exercise is currently promoted clinically but I think it's typically more, 'Take more walks.' But there is a lot of emerging evidence that shows that resistance training not only has similar benefits as aerobic training, but it also has very specific benefits. It's also an option for seniors with limited mobility."

Dr. Ambrose reported that her team hopes to continue following this patient group and is in the middle of a new trial comparing aerobic training to resistance training and to tone and balance training in an at-risk patient population.

Promising Evidence

"Both studies provide very promising evidence that physical activity in any form can improve cognitive function," Marco Pahor, MD, professor and director at the Institute on Aging and chair of the Department of Aging and Geriatric Research at the University of Florida in Gainesville, told Medscape Neurology. Dr. Pahor wrote the accompanying editorial with his colleague Jeff Williamson, MD, MHS, chief of the Division of Geriatric Medicine at Wake Forest University Medical Center in Winston-Salem, North Carolina.

"However, both studies have some limitations," cautioned Dr. Pahor. "The primary limitation of the Etgen study is that it is observational and doesn't provide definitive evidence of cause and effect. The Canadian study is a randomized controlled trial but has a limited sample size of participants and a short duration of 12 months, which is a short time to access the effects on cognition."

"The takeaway is that they provide 1 more piece of evidence that physical activity is a very important factor for improving health in older adults," he concluded. "Both studies are extremely compelling and set the stage for larger multicenter trials to come."

The first study was funded by Allgemeine Orskrankenkasse (a Bavarian health insurance company). The second study was funded by grants from The Vancouver Foundation, the Natural Sciences and Engineering Research Council of Canada, and the Michael Smith Foundation for Health Research and by a New Opportunities Fund from the Canada Foundation for Innovation. None of the study or editorial authors have disclosed any relevant financial relationships.

Arch Intern Med. 2010;170(2):124-125, 170-178, 186-193.