3-D imaging among tools in fight against Alzheimer's
The Canadian Press Mon. Sep. 26 2011

MONTREAL ? Like an ancient explorer discovering the world, Alan Evans plots courses for the future as he maps the brain in 3D.

And one of the paths the scientist at the Montreal Neurological Institute and Hospital hopes to chart is how Alzheimer's makes its steady, devastating advance. "What we're trying to understand is the mechanisms of the disease," said Evans, director of the McConnell Brain Imaging Centre's ACE NeuroImaging Laboratory. His research is one of the many patient and meticulous efforts going on in laboratories around the world as scientists try to crack the mystery of the human brain. Evans said 3D imaging enables researchers to measure the thickness of the brain's cortex, "the mantle around the outside of the brain where the thinking goes on" without taking it out of the skull. The mantle has a typical thickness of three to four millimetres, he said.

"In Alzheimer's disease, it starts to waste away in specific brain areas and it's that wasting away that underlies the memory deficits or the other forms of cognitive deficits." Evans' efforts help researchers to see the differences in the measurements of a normal brain and a diseased brain. In his study, 1,000 normal brains were compared to 1,000 Alzheimer's-affected brains. "What you derive from that kind of computational, statistical analysis is much more reliable, how it is in the population," he said. "This is how Alzheimer's disease changes over time differently from how the normal brain changes over time."

While a major advance, Evans points out it's a long way from helping cure the disease, which currently has no remedy.
"We were able to look non-invasively at the Alzheimer's brain and understand where it starts, how it changes over time in the typical Alzheimer's disease progression. "That starts us into the realm of 'Can we also monitor how well particular therapies do and whether they can either reverse or prevent that deterioration?' That's some way from giving us the mechanism that a drug can interfere with."

Evans noted that it is tricky to get a full understanding of the pathology of a disease like Alzheimer's, saying it's not like a tumour which shows up on an MRI or CT scan or the lesions associated with multiple sclerosis. The "kind of computational, analytic, objective tools" offered by the 3D research not only enables scientists to identify the disease but measure it in potentially hundreds of thousands of subjects.

He explained that the technique has wider applications than solely in Alzheimer's research and that it is used to investigate other forms of dementia and brain development, such as that experienced by children as they grow. But as enthralling as it is to see a baby's brain develop, Evans said it is shocking to see the wasting brought about by Alzheimer's. "You look at it and you think, 'Oh, my God.' This is heartstopping, it's so dramatic," said Evans, who also contributes to an international network that links brain-mapping laboratories.

Dr. Jack Diamond, the scientific director of the Alzheimer Society of Canada, said the research being done by Evans provides a valuable tool in the fight against the disease. "Different areas of the brain shrink more than others in the disease and what he's got here is a sophisticated way of picking up on these early on," Diamond said in an interview. Imaging is but one frontier that is being explored in the battle against Alzheimer's, which Diamond said is being waged on many fronts. He pointed out, for example, that the appropriate imaging can show if a brain is using oxygen and glucose normally. "This is very useful because when the brain's different regions are affected they tend to be affected adversely in the sense that they can no longer metabolize properly . . . it's not using the oxygen and glucose normally."

A recent study released by Minnesota-based doctor Kejal Kantarci also suggested advanced imaging has been able to spot chemical changes in the brain. People with high levels of amyloid-beta deposits and choline / creatine scored lower in memory and language tests than subjects with lower levels. However, researchers said more investigation is needed. Diamond said many researchers are also working on detecting blood markers that could provide information about the disease. Lumbar punctures are now done because changes in the protein levels in spinal fluid can be a warning sign.

But the lumbar puncture is not routine and while generally safe it does carry risks of side effects and infections. The ability to detect changes through blood would be ideal because it is easy to draw, he noted. Diamond also encouraged researchers to get a better hold on what repair mechanisms in the brain can do as well, for example how nerve cells can resist the disease. "We always look at the enemy, the thing that we can correlate as a bad news change," he said. "What we don't have a handle on yet is the other aspect, the defence." Diamond acknowledged that with all this information being amassed, basic public education about Alzheimer's remains a big challenge.

The Alzheimer Society says there are now 500,000 Canadians with the disease, with that number doubling in a generation. Memory loss is a symptom but so are sudden mood swings, repeating words or statements and difficulty in everyday tasks such as getting dressed. Alzheimer's usually strikes people in their 60s but has shown up in some in their 40s.

Diamond said that risk factors include lack of exercise and not using your brain, chronic stress, diabetes, depression, repeated blows to the head, high blood pressure, high cholesterol, cardiovascular disease and an unhealthy diet. "The healthier the lifestyle you have, the less likely you are to get Alzheimer's, but you've got to keep at it," he said. And it can be easier than you think. Take the stairs instead of the elevator, for example. "An hour of gardening is the equivalent of an hour in the gym."