By the time Alzheimer’s symptoms rear their head, brain degeneration is often irreparable. But while the disease has no cure, simple eye tests and smell tests could be used to catch the risks early, according to new research.

Other research also shows exercising both body and mind can work to prevent the disease, although the cause of this most common form of dementia is still mostly unknown.

But while the disease itself isn’t properly understood, people like Sharon Roszel understand its effects too well. Roszel lost her mother and father to Alzheimer’s, and she worries she’s also at risk.

“I don’t want to go through what my parents went through,” she told CTV News. “They were pretty healthy right up to the very end, and they both got Alzheimer’s.”

With the prevalence of Alzheimer’s disease expected to quadruple by 2050, the need for inexpensive and non-invasive tests is becoming important. Research presented Sunday at the Alzheimer’s Association International Conference demonstrated ways to identify the disease at an early stage without having to use brain scans.

Two studies at the Copenhagen gathering showed a link between a weakened sense of smell and loss of brain cell function, while two others showed researchers were able to identify people with Alzheimer’s based on levels of a certain molecule found in the eye.

The smell tests

Two studies, one from Harvard Medical School and one from Columbia University, examined the connection between cognitive degeneration and an inability to correctly identify odours.

Matthew E. Growdon and the rest of his Harvard team found that poor smell identification and worse memory were associated with certain parts of the brain being thinner. He said the research, which involved giving a scent-identification test to more than 200 people from the Harvard Aging Brain Study, could be used for testing older individuals who are at risk of developing Alzheimer’s disease.

"For example, it may prove useful to identify proper candidates for more expensive or invasive tests,” said Growdon in a press release.

In a separate study, researchers at the Columbia University Medical Centre followed the progress of more than 1,000 people who originally showed no signs of the disease. In 2004, the team administered the same smell test that was used in the Harvard study to a group with an average age of about 80 years old.

Psychiatry professor Davangere Devanand said lower scores on the smell test were correlated with those who later developed Alzheimer’s disease and dementia.

"If further large-scale studies reproduce these results, a relatively inexpensive test such as odour identification may be able to identify subjects at increased risk of dementia and Alzheimer's disease at a very early stage,” said Devanand in a release.

The eye tests

Alzheimer’s disease is associated with a build-up of something called beta-amyloid plaques in the brain. Researchers have found similar plaques in the retinas of people with the disease, and in preliminary research presented by the Commonwealth Scientific and Industrial Research Organization in Australia, researchers were able to differentiate between Alzheimer’s patients and healthy patients based on retinal scans.

"If further research shows that our initial findings are correct, it could potentially be delivered as part of an individual's regular eye check-up,” said Shaun Frost, a researcher at the CSIRO, in the release.

A similar study with comparable results was carried out by Massachusetts-based research company Cognoptix, which found a correlation between beta-amyloid levels in the lens of the eye with levels found in the brain through PET scans.

Diagnosis, but no cure

While new research might provide tools for early and reliable diagnosis, Alzheimer’s is still a disease that leads to death 100 per cent of the time. And for those who’ve had to witness the symptoms first hand, identifying the risks isn’t enough.

“Until they find a cure, or find out what causes Alzheimer’s, I just take everything with a grain of salt,” said Roszel.

Ian Cohen, a doctor with the Toronto Memory Program, understands the frustration.

"There have been many trials that have taken place over the last number of years, and unfortunately we haven't had a new breakthrough in medication for this disease," Cohen told CTV News. “So what we’re left with are a few drugs that help with symptoms only.”

Cohen said tests for biological markers of the disease, like beta-amyloid plaque, could work to inform or reassure those with a family history of Alzheimer’s. Those at risk can also take steps to either prevent or delay the onset of the disease, said Cohen.

Physical activity can work to control hypertension and obesity, which are both risk factors for the disease. Depression and obesity have also been identified as increasing the chances of developing the symptoms of Alzheimer’s, he said.

Low levels of education are also correlated with higher chances of developing the disease, which Cohen said has to do with brain “fitness.”

“The more you learn, the stronger the connections are in your brain,” he said.

“If you don’t use a muscle, you lose it. If you don’t use your brain, you put yourself at risk.”

With a report from CTV News' Peter Akman