A simple “sniff” test to evaluate an individual’s sense of smell is gaining credence as a means of diagnosing early Alzheimer’s disease.

Neurologists have been eager to find new ways to identify people who are at high risk of Alzheimer's dementia but do not yet show any symptoms. There is a widespread consensus that Alzheimer's medications now under development may not work after dementia has set in

Although no such test for early diagnosis is as yet available, there is increasing evidence that a loss that the sense of smell declines sharply in the early stages of Alzheimer’s disease.

Now a study from the Perelman School of Medicine at the University of Pennsylvania confirms that administering a simple "sniff test" can enhance the accuracy of diagnosing this dreaded disease.

The researchers administered a simple, commercially available test, known as the Sniffing' Sticks Odor Identification Test, is one in which subjects must try to identify 16 different odors.

The team also gave the study’s participants a cognitive test to evaluate their thinking ability.

The subjects had already been evaluated by doctors at Penn with an array of neurological methods, and according to expert consensus had been placed in one of three categories: "healthy older adult," "mild cognitive impairment," or "Alzheimer's dementia."

The researchers used the results from the cognitive test alone, or combined with the sniff test, to see how well they identified subjects in each category.

As researchers report, the sniff test added significantly to diagnostic accuracy when combined with the cognitive test.

The study appears in Journal of Alzheimer’s Disease.