Are you at risk of developing Alzheimer’s disease? It appears your nose may know.
In a growing body of research, an inability to identify common scents has been associated with the development of mild cognitive impairment – a precursor to Alzheimer’s disease. Older adults who have difficulty identifying odors such as lemon or cinnamon are more likely to have problems with thinking, learning and memory, according to one such study by Chicago researchers.
That may sound a bit far-fetched. But scientists know that protein deposits called tangles begin to appear in a region of the brain responsible for smell before symptoms of Alzheimer’s disease manifest themselves. An inability to identify some scents has been linked to other neurological disorders, including Parkinson’s disease, and scientists are still attempting to understand why this is.
The findings are raising hopes that doctors may one day be able to administer a sort of “scratch ‘n sniff” test to gauge olfactory abilities as part of determining a person’s risk of Alzheimer’s disease.
This line of research “may in combination with other diagnostic tests help to improve early detection” of Alzheimer’s disease, stated researchers from the New York State Psychiatric Institute in a separate study. The scientists analyzed more than three dozen common scents and the ability of people with Alzheimer’s disease or mild cognitive impairment to smell them. They determined the scents that are the best predictors of Alzheimer’s disease are strawberry, smoke, soap, menthol, clove, pineapple, household natural gas, lilac, lemon and leather.
“Olfactory deficits, which have been observed consistently in Alzheimer’s disease, occur early, are predictive of a future diagnosis of Alzheimer’s disease and increase with disease severity,” they concluded.
Note, however, that there are many other causes of altered smell including nasal allergies, sinus problems, and even certain tumors.
At Navigenics, which offers assessment of Alzheimer’s risk as part of our genetic health service, we are tracking this line of Alzheimer’s research as part of the prevention and detection strategies we suggest to our members. Knowing your Alzheimer’s risk may encourage you to make lifestyle changes that might reduce that risk, as was shown in an important study. While there is no foolproof way to prevent the onset of the disease, exercising your body and your mind may improve blood flow to the brain and help compensate for the brain’s degeneration. It may even generate new brain cells.
A smell test for patients might prove to be useful, but there are some limitations. “Not all low scorers went on to have cognitive problems,” Chicago study author Robert Wilson told the Associated Press.
In other words, a diminishing sense of smell shouldn’t be reason to panic, but it should be noted and brought to the attention of your physician.
Kathy Golla Mar 16, 2009
What an interesting article! Thanks!