New Scent Recognition and Recall Test Could Better Predict Onset of Alzheimer’s Disease

If you are wondering about your risk of developing Alzheimer’s disease, the answer may be found right under your nose.

A Mass General research team has developed a series of four tests designed to measure early indications of Alzheimer’s disease based on an individual’s ability to recognize, remember and distinguish among odors.

The 30-minute scent test was given to 183 people between 60 and 80 years old – some with mild cognitive impairment or possible Alzheimer’s disease—and of those, about 20 percent showed signs of olfactory deficiencies.

Genetic and imaging testing revealed that that these same individuals had other deficiencies that have been linked to the illness, including thickening of certain brain structures and a mutation in a gene associated with increased risk of Alzheimer’s disease.

While Alzheimer’s disease is known to affect brain structure involved in odor perception, previous tests have not been effective screening tools since the natural ability to identify and distinguish among scents varies greatly among individuals.

The new test developed by Mark Albers, MD, PhD, of the Center for Alzheimer’s Research, takes a four-part approach that includes identification, emotional association, memory and differentiation.

For example in one test, participants were presented with a series of 10 odors—menthol, clove, leather, strawberry, lilac, pineapple, smoke, soap, grape or lemon. They were asked if they could recognize the scent and if they could identify it from a list of four options.

In a subsequent test, the participants were presented with 20 odors, 10 of which were repeats from the first test and 10 that were new. The participants were not only asked to identify each odor, but also to recall if it was included in the first test.

It is estimated that there is a 10-year gap between the start of Alzheimer’s disease in the brain and the first outward manifestation of symptoms. If researchers can better identify individuals in the very early stages of the disease, they may be able to develop therapies that will slow or halt its progression.