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A simple scratch-and-sniff test could flag the first signs of Alzheimer's disease. As this ScienCentral News video reports, the memory researcher who's developing the test hopes to give doctors a jump on curtailing the devastation.
Sniffing Out Early Alzheimer's
Memory slipping, Thelma Walton strains to read, something she had no trouble with five years ago. Her husband, Jim, prompts her every morning with simple math equations and writing tasks, constantly repeating patterns laid in her brain long ago. Now hard at this work, the promise of retirement and a leisurely everyman's every day is no longer theirs to enjoy. For Thelma and Jim, her Alzheimer's disease is fresh at every waking.
"It's a frustrating disease," says Jim, a seventy-something retiree living in Raleigh, North Carolina. "You see a whole body and you expect that whole body to perform like it always did and it's not going to do that. The mind's not going to function that way."
Slowly, as Alzheimer's creeps through the brain, it's likely to first affect something we take for granted: our library of smells. "Identifying smells involves not only perceiving the smell but comparing against your bank of smells in the brain," explains D.P. Devanand, a memory disorder researcher and co-director of the Memory Disorders Center at the New York State Psychiatric Institute. "People lose their memories for the smells that they had all their lives."
Now, Devanand and a team of researchers have developed a simple scratch and sniff smell test aimed at detecting Alzheimer's early on, when olfactory memory wanes as a small brain area beneath the medial temporal lobe—it directs smell—starts accumulating tangles of stringy protein strands.
Devanand's five-year study tracked 150 people with mild memory loss and Alzheimer's disease and 63 healthy adults. Both groups scratched, sniffed and tried at least once a year to identify ten smells—lemon, strawberry, smoke, soap, menthol, clove, pineapple, natural gas, lilac and leather. People with mild memory loss who score lower on the test are much more likely to develop Alzheimer's, says Devanand, who spent over ten years researching memory loss and smell before presenting his latest findings to colleagues at the 2004 meeting of the American College of Neuropsychopharmacology.
To be sure of the test's effectiveness, Devanand compared his study results with MRI scans that show brain volume loss and are being refined to detect early Alzheimer's. "In terms of accuracy and prediction, one could think of detailed memory and neuropsychological testing as being more than 80 percent accurate in predicting who will develop Alzheimer's, and the smell test seems to have comparable predictive ability," he says.
Because there isn't a test that definitively nails down an Alzheimer's diagnosis, any new tools moving in that direction draw attention in professional circles that treat some of the estimated 4.5 million Americans that the Alzheimer's Association reports suffer from the disease. Starting to combat Alzheimer's early, "can help in terms of planning for the future for the patient and family," Devanand says. And though he adds that current treatments are only mildly effective, on the horizon are trials of new drugs that "may be much more powerful."
One promising approach is to target the genes that trigger Alzheimer's. Thelma Walton has given her DNA to researchers at the Center for Human Genetics at Duke University Medical School in the hope that they can develop such a drug: "I think others will be working on it too, all over the country, no question," she says. "It's going to be better and better for the next generation."
Until then, the burden the disease brings will fall onto the shoulders of one in ten American families, reports the Alzheimer's Association, which has recorded more than double the number of cases since 1980, with new cases expected to climb to as many as 16 million. That puts a lot of pressure on researchers like Devanand who are trying to pull through with new diagnostic tools. Will his simple scratch and sniff test live up to its promise? Not standing alone, says Devanand: "Because Alzheimer's is a complex condition with many things going wrong in the brain, it's unlikely that any one test will be sufficient for a foolproof diagnosis." Instead, the smell test could serve as one more way to pinpoint the disease in its early stages, he says.
Still, any extra confirmation that Alzheimer's has started its slow march buys families like the Waltons more time to devise ways to stall the disease as researchers slowly unravel what lurks behind the devastation that is Alzheimer's.
This research was presented at the 2004 American College of Neuropsychopharmacology meeting and was funded by the National Institute on Aging.
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