Understanding Alzheimer’s

In Depth Mental Health
Understanding Alzheimer’s
Last Updated Jan. 10, 2007

CBC News

Alzheimer’s is the most common form of dementia and affects one in 20 Canadians over 65 — about 290,000. The number rises to one in four in those over 85.

The disease slowly leads to memory impairment, behavioural changes and dementia, affecting how people understand, think, remember and communicate.

There is currently no cure for Alzheimer’s, but researchers say they’ve made progress in finding out more about the disease. They believe Alzheimer’s begins to attack the brain years before the symptoms appear, so determining what causes the disease and who’s susceptible to it are critical to researchers in the field.

“We definitively know that genes are involved — familial transmission of defective genes, and also some less obvious but very interesting findings recently suggest that what we traditionally viewed as risk factors for heart disease also happen to be risk factors for Alzheimer’s,” said Dr. Judes Poirier, director of the McGill Centre for Studies in Aging, in an interview with CBC-TV in September 2006.

Poirier said early studies suggest people in mid-life with uncontrolled hypertension, high cholesterol levels and even diabetes that’s not treated are at risk of developing Alzheimer’s disease.

Researchers gave anti-diabetic drugs to Alzheimer’s patients with surprising success, said Poirier. They also saw some effect from anti-cholesterol and anti-hypertensive drugs.

“What we have are real drugs, used for other purposes that may have a tremendous impact in Alzheimer’s disease as well,” said Poirier.

Possible Alzheimer’s ‘fingerprint’?

In December 2006, researchers at New York’s Weill Cornell Medical College discovered what they described as a “fingerprint” of Alzheimer’s disease. They identified a pattern of 23 proteins floating in spinal fluid that, in preliminary testing, seems to indicate Alzheimer’s with some accuracy.

Currently the only definitive way to diagnose Alzheimer’s is through autopsy. But the finding could pave the way for a test to determine whether a person may develop Alzheimer’s later in life.

Using a technology called proteomics, the researchers examined 2,000 proteins found in the spinal fluid of 34 people who died with autopsy-proven Alzheimer’s, comparing it with the spinal fluid of 34 non-demented people.

What emerged as a difference were 23 proteins, many that by themselves had never been linked to Alzheimer’s, but that together formed a fingerprint of the disease.

The researchers then looked for the same protein pattern in 28 more people. Some had symptoms of Alzheimer’s or other dementia. Others were healthy. The test indicated Alzheimer’s in nine out of 10 patients that doctors suspect have it. But it also incorrectly pointed to Alzheimer’s in three people who were healthy.

Diet and Alzheimer’s

Drinking fruit and vegetable juice frequently may help delay the onset of Alzheimer’s disease, a finding that reinforces the importance of a healthy diet.

Research released in August 2006 in the U.S suggests something as simple as a glass of freshly squeezed juice three or more times a week seemed to dramatically reduce the developing signs of Alzheimer’s.

As in diabetes, the disease makes the body produce more nasty oxygen radicals — damaging chemicals produced during metabolism.

Recently, researchers in California concluded Alzheimer’s is a disease of aging because part of the brain’s cleanup crew that clears away the toxic buildup of free radicals becomes less efficient, increasing susceptibility to the disease.

Our bodies use anti-oxidants in foods to neutralize the damage.

Delaying onset

To look at the effect of diet on the risk of developing Alzheimer’s, researchers in the U.S. followed almost 2,000 dementia-free people for up to 10 years, collecting information on their diet and assessing their cognitive function every two years.

They found the risk of developing signs of Alzheimer’s was 76 per cent lower among people who drank three or more servings of juice per week compared with those who drank it less than once per week.

“Fruit and vegetable juices may play an important role in delaying the onset of Alzheimer’s disease,” Dr. Qi Dai of Vanderbilt University Medical Center in Nashville, Tenn., wrote in the September issue of the American Journal of Medicine.

The researchers originally suspected anti-oxidants such as vitamin C in the juice might be protective, but clinical studies did not support the idea.

“What this new study showed is in these juices, it isn’t the vitamins that’s protective, it’s these polyphenols, and that’s the surprising thing,” Dr. Jack Diamond, scientific director of the Alzheimer’s Society of Canada, told CBC News.

Animal and cell culture studies suggest polyphenols in juice pressed from whole, fresh fruits and vegetables show a stronger neuroprotective effect than the vitamins, the team noted. Protective polyphenols are mostly found in the skin or rind of fruits and vegetables. They tend to disintegrate when heated, Diamond said.

Population differences

Dai’s study was part of a larger research project comparing Alzheimer’s disease and dementia in older Japanese populations living in Japan, where incidence of Alzheimer’s is low, to Japanese people living in Hawaii and Seattle, Wash. The difference in incidence rates suggests environmental factors including diet and lifestyle may be important.

Even when different populations consumed the same vitamin content, it was the people who drank more fruit and vegetable juice that gained the greatest protection.

The protective effect won’t necessarily stop Alzheimer’s, but it reduced the chances, after controlling for other factors such as smoking, education, physical activity and fat intake that could also play a role.

The benefit was enhanced in people who carried a genetic marker called apolipoprotein E that is linked to late-onset Alzheimer’s, as well as those who were not physically active.

Although the large number of people studied across populations over a long time are assets of the study, Dai cautioned it’s important for people not to jump the gun on the potential protective value of juice, and they can’t say what type of juice might help or how long it needs to be consumed.

Previously, clinical trials, a more rigorous form of research, did not pan out for using antioxidant vitamins or hormone replacement therapy to prevent or slow Alzheimer’s, Dai said.

While some dieters may be told to avoid the excess calories in juice, the research adds to evidence on how fruits and vegetables improve health. The foods help blood pressure and keep blood vessels healthy.

Canadian researchers are also looking at non-dietary strategies for curbing the nerve damage of Alzheimer’s.

Researchers at the Centre for Research in Neurodegenerative Diseases at the University of Toronto discovered a protein blocks the creation of nerve toxins in Alzheimer’s.

If scientists can understand how the protein prevents the toxic build-up, it could lead to more specific treatments with fewer side-effects, according to Dr. Georges Levesque, chair of the biomedical review panel at the Alzheimer Society of Canada.

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