'Sniff test' may help reveal if you're at Alzheimer's risk

Soon, diagnosing early Alzheimer's disease may be as simple as measuring a person's sense of smell.

A new 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 sniff test also appears to be useful for diagnosing a pre-dementia condition called mild cognitive impairment (MCI), which often progresses to Alzheimer's dementia within a few years.

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.

"There's the exciting possibility here that a decline in the sense of smell can be used to identify people at risk years before they develop dementia," said principal investigator David R. Roalf.

Roalf and his colleagues used a simple, commercially available test known as the Sniffin' Sticks Odour Identification Test, in which subjects must try to identify 16 different odours. They administered the sniff test, and a standard cognitive test (the Montreal Cognitive Assessment), to 728 elderly people.

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

"These results suggest that a simple odour identification test can be a useful supplementary tool for clinically categorizing MCI and Alzheimer's, and even for identifying people who are at the highest risk of worsening," Roalf said.

"We're hoping to shorten the Sniffin' Sticks test, which normally takes 5 to 8 minutes, down to 3 minutes or so, and validate that shorter test's usefulness in diagnosing MCI and dementia--we think that will encourage more neurology clinics to do this type of screening," Roalf added.

Roalf and his laboratory also plan to investigate whether protein markers of Alzheimer's, which are present in the olfactory region of the brain before dementia occurs, can be detected in nasal fluid to provide an even earlier warning of the disease process.

Studies suggest that a high proportion of older adults who have cognitive impairment are not identified as such, in part due to lack of adequate screening.

The study is published in the Journal of Alzheimer's Disease.