A century after German doctor Alois Alzheimer (1864-1915) described the first documented case of Alzheimer's disease -- a serious cognitive decline suffered by elderly patients -- Chinese scientists may have discovered one of the illness' hidden facets. Their discovery reveals one more piece of the puzzle on this mysterious affliction, which affects millions worldwide.
The most striking early symptom of Alzheimer's is short-term memory loss, oft seen first as minor forgetfulness that worsens along with the illness, with a tendency to preserve older memories. As the disorder progresses, intellectual losses spread to language, movement co-ordination and recognition. When we know these abilities are seen as essential for quality of living, one can see the true devastating effect Alzheimer's disease has upon both its sufferers and their loved ones.
It is rapidly becoming one of the leading diseases among elderly people worldwide. The average cost of treatment and care for an Alzheimer's patient is over US$100,000 worrying many that this will over-stretch preciously thin health budgets if baby-boomers begin to fall ill in the same proportions as previous generations.
On November 20, a research team led by Pei Gang of the Shanghai Institute of Biochemistry and Cell Biology (SIBCB) of the Chinese Academy of Sciences (CAS) published its studies in the premier journal Nature Medicine. It was revealed that the activation of a certain part of a brain cell called the 2-adrenergic receptor may well be one of the culprits.
Over decades of research, scientists have learned that a substance known as amyloid plaque is the primary cause of Alzheimer's.
Amyloid plaque is produced by protein metabolism in certain areas of the brain. In healthy people, amyloid plaque is rapidly metabolized by their immune systems. However, if a person's brain cells produce abnormally high levels of amyloid plaque whilst their immune system lessens its ability to cleanse the plaque, it will begin to accumulate in the brain.
This accumulation twists nerve filaments together, killing substantial numbers of nerve cells. However, little is known about how amyloid plaque formation is regulated.
Drug treatments can only reduce the accumulation of amyloid plaques and lessen the symptoms of Alzheimer's disease; however, there is no cure.
Amyloid plaque formation has been the primary concern of Pei and his colleagues, including Ni Yanxiang of SIBCB, the first author of the paper published in Nature Medicine.
"As early as 2001, we have been focusing our studies on a molecule called presenilin, because it has been reported that more than 100 mutations of this molecule are related to Alzheimer's disease," Ni told China Daily.
Among new discoveries, Ni's focus shifted to other substances whose activities are associated with, but not decided by, presenilin. The 2-adrenergic receptor is one of them.
After activating the 2-adrenergic receptor in mice with Alzheimer's disease for a long time, scientists found that a greater accumulation of amyloid plaques developed in the mice's brains. Consequentially, the mice show accelerated syndromes of Alzheimer's disease.
On the other hand, Ni and his colleagues discovered that using a chemical called 2-adrenergic receptor agonist inhibits the plaque's accumulation.
The repeated studies have verified the link between 2-adrenergic receptor and the accumulation of amyloid plaques.
"The discovery implies an innovative way to prevent amyloid plaque formation and the consequential onset of Alzheimer's disease," Ni said. He said his research team has applied to internationally patent using 2-adrenergic receptor agonist to treat Alzheimer's.
There is a long way to go before the discovery can be used to develop a new drug, but Ni said that stress, nervousness and anxiety activate the 2-adrenergic receptor.
"If we try to lead an easy life, avoiding stress as much as possible, we can largely reduce the risk of developing Alzheimer's disease," he said.
The studies by scientists and doctors worldwide could enhance the research of the Shanghai scientists who traced the relationship between Alzheimer's disease and stress.
Late last year, scientists at the US-based Utah University found that eating more fruits and vegetable can slow the decline of an aging person's memory, which is often the first sign of Alzheimer's.
However, a separate study conducted by researchers at the US-based Accera Pharmaceuticals, in Colorado, says that the benefits of eating vegetables should not make people to become vegetarians.
According to their studies, published in Nutrition and Metabolism journal in late 2005, scientists say that a high intake of fat and low consumption of carbohydrates can reduce the deposit of amyloid plaques.
It is also widely observed that moderate wine drinking slows the onset of Alzheimer's.
Besides food and drink, a more active social life could not only delay the onset of the Alzheimer's, but also reduce its effects on diagnosed patients, according to research by David Bennett at the Chicago-based Rush University.
In a study published in early October in the journal Alzheimer's, US scientists discovered that curcumin, an extract from turmeric, curry and ginger, plays a powerful role in curbing the onset of the Alzheimer's.
The study indicates that immunity cells distilled from Alzheimer's patients which have been treated with curcumin are more effective in metabolizing amyloid plaques.
While scientists are further exploring the molecular mechanisms by which curcumin battles the onset of Alzheimer's, traditional Chinese medicine (TCM) doctors say that using herbal extracts could demonstrate TCM's capability to combat the disease.
For a long time, without knowing the name of the disease let alone the molecular mechanisms that cause Alzheimer's, TCM doctors have been documenting its various symptoms. TCM attributes its causes to the exhaustion of the kidney and consumption of brain marrow.
"The principles of (TCM) treatment are tonifying the kidney and activating blood circulation," said Zhu Zhuangzhuang, a gerontics doctor of Wuhan General Hospital of Guangzhou Military Command Zone.
Based on the disease's symptoms, TCM doctors have given combinations of herbs such as shudi (Radix Rehmanniae Praeparata), fuling (Poria), gouqi (Fructus Lycii) and shanyurou (Fructus Corni).
In recent years, extracts of gingko have been tried as a more experimental method to help treat Alzheimer's disease. The resulting data has been positive.
"As of now, scientists cannot clearly explain all of the mechanisms relating to the onset of Alzheimer's, but one thing is clear: It is a result of a combination of factors including the environment, aging, lifestyle and food intake. TCM has an advantage in comprehensively considering the different factors together," Zhu wrote in her review articles.
(China Daily November 28, 2006)