Diminished Sense of Smell May Indicate Onset of Alzheimer's Disease

The loss of smell may be an early indicator of Alzheimer's disease, according to results from a recently released five year study funded by the National Institute on Aging and the Illinois Department of Public Health and reported on by the Associated Press (AP).

Individuals were asked to identify smells. Researchers found that difficulty identifying odors also was associated with a higher risk of progressing from mild cognitive impairment to Alzheimer's disease. Those who misidentified or made at least four errors of smell were 50 percent more likely to develop problems than individuals who made one error or less, according to the AP.

Link to smell
A key method for reaching individuals with Alzheimer's disease and other forms of dementia is tapping into familiar routines and deep-rooted values. The sense of smell is one of the most powerful methods of tapping into memories.

Researchers believe that the microscopic hallmark lesions of Alzheimer's disease first appear in a brain region important to the sense of smell, as reported by the AP. Doctors at the Rush University Medical Center in Chicago asked participants to identify the following familiar smells: onion, lemon, cinnamon, black pepper, chocolate, rose, banana, pineapple, soap, paint thinner, gasoline and smoke. Over the course of the five year study, 600 participants ages 54 through 100 took 21 cognitive tests. The AP reports about one-third of the people developed at least mild trouble with memory and thinking, and lower scores predicted higher risk of cognitive decline, regardless of age, gender, education and a history of strokes or smoking.

Future impacts
Findings like those from the smell study could be important to slowing or stopping the progression of Alzheimer's disease and the severe memory loss associated with it. Currently Alzheimer's disease has no cure, and more than 5 million Americans (representing about 13 percent of Americans over the age of 65 and nearly 50 percent over the age of 85) are affected by the disease, according to statistics from the Alzheimer's Association. Since scientists predict that the number of individuals with Alzheimer's or some other form of dementia could reach 8 million by 2025, any and all information about Alzheimer's is valuable for research and practical purposes.

Scientists are looking for ways to detect the disease in its early stages in order to start treatment sooner. According to data from the Rush University Medical Center in Chicago, increased levels of mental activity such as crosswords and reading, physical exercise, and heart-healthy eating habits are all associated with reduced risk of mild cognitive impairment. Current treatments are limited to drugs and mental exercises that simply prolong the onset of severe symptoms.
As the study indicates, in the future a simple "scratch and sniff" test may help indicate the onset of Alzheimer's disease. And with Alzheimer's, early knowledge and treatment will lead to a higher quality of life for a longer period of time.

Sources:

Carla K. Johnson, Associate Press, Poor sense of smell may be Alzheimer's, July 3, 2007 at http://fe42.news.sp1.yahoo.com/s/ap/20070702/ap_on_he_me/alzheimer_s_sense_of_smell_2

Robert S. Wilson, PhD; Julie A. Schneider, MD; Steven E. Arnold, MD; Yuxiao Tang, PhD; Patricia A. Boyle, PhD; David A. Bennett, MD, Archives of General Psychiatry, Vol 64, p. 802-808, July 2007, Olfactory Identification and Incidence of Mild Cognitive Impairment in Older Age at http://archpsyc.ama-assn.org/cgi/content/short/64/7/802

Alzheimer's Association Fact Sheet

Rush University Medical Center