다음의 글은 밑에 Beau Kim님께서 소개하신 글이다. 한 10여년 전 까지만 해도 치매 특히 알츠하이머씨 병은 유전적 원인에 의해 발병하는 것이라는 생각이 지배적이었다. 가장 중심에 되는 유전자가 아밀로이드 프레커서 프로틴이라는 유전자로 이 유전자가 어떻게 잘못 되면 단백질이 잘못 잘리게 되고 잘못 잘린 작은 단백질 조각인 펩타이드가 플라크를 형성하고, 이 플라크 주위의 뇌세포가 죽기 때문에 기억 상실이나 인성 변화가 야기된다는 이론이 중심이었다.

따라서 여기에 연관된 유전자들을 찾기에 정말로 혈안이 되었었다. APP (아밀로이드 프레커서 프로틴)의 유전자 돌연변이도 여러개 찾아내었고, 이 단백질을 자른는 부분이 되는 프레시넬린 1, 2 라는 유전자의 변형도 찾아내었고, 지질 대사에 관계하는 에이포 리포프로틴 이라는 유전자가 각 사람마다 여려 형태를 가지고 있는데 그 중에 제 4형 (혹은 E형)을 가지고 있으면 알츠하이머 발병이 현저히 증가한다는 사실을 알아냈다.

하지만 그게 다이다..위의 변형된 유전자들을 가지고는 일반 사람들이 왜 알츠하이머에 걸리는지를 설명할 방법이 없다. 위의 유전자들이 멀쩡한 사람들도 병에 걸리기 때문이다. 전체 인구의 90 퍼센트 이상은 유전자에 변형이 없는데도 이 병에 걸린다...다른 유전자가 또 있을 것이라는 주장은 터무니 없는 소리다. 그 많은 사람들이 20여 년 간을 이 잡듯이 뒤졌는데도 나오지 않는다면 이 병을 유발하는 키 유전자 (결정 유전자)가 존재하지 않음은 명확하다.

그래서 다음으로 등장한 이론이 치매는 대사과정의 산물이라는 거다. 인간의 몸은 끊임 없는 대사를 해야 하고, 그 과정의 산물로 알츠하이머가 발병한다는 생각이 일견 맞아보인다. 하지만 여기에 그렇다면 왜 어떤 사람에게는 발병하고 어떤 사람에게는 발병하지 않는가 하는 의문이 제기된다.

그래서 점점 수렴해 가는 생각이, 알츠하이머씨 병은 아직 우리가 잘 알지 못하는 환경적 요인 때문에 인간의 대사 과정 부산물로 생기는 병이라는 거다.


따라서 아직 밝혀지지 않은 그 환경적 요인만 찾아내면 이 병은 정복할 수 있는 것이다. 환경적 요인으로 들 수 있는 것은 수 없이 많지만 그 중에 가장 주목받고 있는 이론은 음식이다. 그리고 또 한가지 빼 놓을 수 없는게 인간의 삶에 대한 태도이다.

다음의 글은 이를 설명할 수 있게하는 연구를 소개한다. 조그만 가능성이 보이면 우리는 거기에 집중해 연구하고, 답을 얻어낼 수도 있지 않을까 생각한다.


기쁘게 살고, 열심히 두뇌를 쓰고, 육고기 덜 먹고 올리브 기름 많이 먹고 (메디테라니안 다이어트를 하는 사람들의 그룹이 알츠하이머가 낮다는 연구 보고가 있다), 단 것 덜 먹고 (제 2형 당뇨병 환자는 정상인에 비해 알츠하이머에 걸릴 확률이 2 배나 더 높다)






July 16, 2013
Dementia Rate Is Found to Drop Sharply, as Forecast
By GINA KOLATA

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.

The British researchers, led by Dr. Carol Brayne of the Cambridge Institute of Public Health, took advantage of a large study that tested 7,635 randomly selected people, ages 65 and older, for dementia between 1984 and 1994. The subjects lived in Cambridgeshire, Newcastle and Nottingham. Then, between 2008 and 2011, the researchers assessed a similar randomly selected group living in the same areas.

“We had the same population, the same geographic area, the same methods,” Dr. Brayne said. “That was one of the appeals.”

But Dr. Carrillo questioned the data because many subjects had declined to be assessed: the researchers assessed 80 percent of the group it approached in the first round and 56 percent of those approached in the second. Her concern is reasonable, Dr. Brayne said, but the researchers addressed it by analyzing the data to see if the refusals might have skewed the results. They did not.

In the Danish study, Dr. Kaare Christensen of the University of Southern Denmark in Odense and his colleagues compared the physical health and mental functioning of two groups of elderly Danish people. The first consisted of 2,262 people born in 1905 who were assessed at age 93. The second was composed of 1,584 people born in 1915 and assessed at age 95. In addition to examining the subjects for physical strength and robustness, the investigators gave them a standard dementia screening test, the mini-mental exam and a series of cognitive tests.

The investigators asked how many subjects scored high, had scores indicating dementia and were in between. The entire curve was shifted upward among the people born in 1915, they discovered.

Dr. Anderson, of the National Institute on Aging, said the news was good.

“With these two studies, we are beginning to see that more and more of us will have a chance to reach old age cognitively intact, postponing dementia or avoiding it altogether,” he said. “That is a happy prospect.”