For predicting Alzheimer’s, the nose may know

For predicting Alzheimer’s, th...
A declining sense of smell may be an earlier indicator of Alzheimer's disease
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When it comes to medications that are being designed to treat Alzheimer's disease, it is widely believed that they may only work if they're administered before dementia sets in. This means that it's vitally important to detect the onset of Alzheimer's as early as possible, and a new test could help doctors do just that. It involves getting patients to smell things.

Previous research has already suggested that a decrease in the sense of smell is linked to Alzheimer's. Led by Dr. David R. Roalf, a team from the University of Pennsylvania decided to put that theory to the test.

In order to do so, they assessed a total of 728 seniors using both the standard Montreal Cognitive Assessment test, along with the commercially available Sniffin' Sticks Odor Identification Test – in the latter, participants have to correctly identify 16 scents.

All of the seniors had been previously evaluated at the university, using "an array of neurological methods." Each one was thus placed in one of three categories: healthy older adult, mild cognitive impairment [MCI], or Alzheimer's dementia.

Based only on the cognitive test, Roalf's team was able to correctly identify approximately 75 percent of the MCI group. When the results of the sniff test were factored in, however, that amount increased to 87 percent. The MCI group is an important one, as mild cognitive impairment is known to occur a few years before actual Alzheimer's follows.

That said, combining the results of the cognitive and sniff tests also increased the accuracy of identifying subjects belonging to the other two groups.

Roalf is now trying to streamline the sniff test, so that it becomes widely adopted.

"We're hoping to shorten the Sniffin' Sticks test, which normally takes five to eight minutes, down to three minutes or so, and validate that shorter test's usefulness in diagnosing MCI and dementia," he says. "We think that will encourage more neurology clinics to do this type of screening."

Source: University of Pennsylvania

As the olfactory sense wanes with the process of aging, the author should be cautious about causing unnecessary worry. See, for example: "As we get older, our olfactory function declines. Not only do we lose our sense of smell, we lose our ability to discriminate between smells. It has been reported that more than 75% of people over the age of 80 years have evidence of major olfactory impairment, and that olfaction declines considerably after the seventh decade". (Effects of ageing on smell and taste J M Boyce and G R Shone Postgrad Med J. 2006 Apr; 82(966): 239–241
amazed W1
Not having read the paper, it is vital to know whether it is attempting a simple correlation or looking at causation. This is the old medical argument about when to treat symptoms or when to try the latter as it is more than likely that the Boyce and Shone paper simply reports what Roalfs team have observed whereas Roalf's team go further and point out that the loss of smell is a sympton, yes, but that the cause has much more serious effects, so that the sympton should initiate a deeper investigation and even automatic treatment for Alzheimers.
Don Duncan
Why wait for a test? Why not treat all elderly? If I knew of a cure I would start it immediately at 76 rather than wait. What's the advantage both ways? We don't ever get a thorough analysis.