As the Mind Slips, So May Sense of Smell
Loss might serve as an early sign of cognitive decline

(HealthDay News) -- Losing the ability to identify odors might be more than just annoying: It could also be an early sign of cognitive decline.

Robert S. Wilson, a senior neuropsychologist at the Rush Alzheimer's Disease Center in Chicago , told HeathDay that "people who already have mild cognitive impairment have difficulty with odors." But how the timing of sensory loss might relate to the start of cognitive impairment was unclear, he said.

To investigate that, Wilson and a group of researchers enlisted 589 people who were not cognitively impaired and who averaged about 80 years old. They were given a test in which 12 common odors were placed under their noses and, based on their ability to identify each odor, they were given points, from one to 12. Also, annually for the next five years, the participants were given neurological and cognitive function tests.

In that time, 177 participants developed the kind of mild cognitive impairment that can be a warning sign of future Alzheimer's disease.

The researchers found that the development of mental impairment was associated with a decrease in the ability to identify odors. Those who scored below average on the odor identification test were 50 percent more likely to develop mild cognitive impairment than those who scored above average.

That finding is in line with a leading theory about the development of Alzheimer's, Wilson said. The theory centers on the idea that Alzheimer's begins with trouble in certain areas of the brain, then spreads more widely until it involves the major thinking areas.

Although medical experts are still working on ways to detect and treat the disease, 10 warning signs have been identified, according to the Alzheimer's Association:

• Memory loss. Forgetting recently learned information is one of the most common early signs of dementia.
• Difficulty performing familiar tasks. People with dementia often find it hard to plan or complete everyday tasks.
• Problems with language. Forgetting simple words or substituting unusual words can make people's speech or writing hard to understand.
• Disorientation to time and place. People with Alzheimer' can become lost in their own neighborhood, forget where they are and not know how to get back home.
• Poor or decreased judgment. Signs include inappropriate dressing, such as wearing several layers on a warm day or little clothing in the cold.
• Problems with abstract thinking. A person might have difficulty performing complex mental tasks, such as forgetting what numbers are for or how they should be used.
• Misplacing things. Possessions frequently are put in unusual places.
• Changes in mood or behavior. Rapid mood swings, from calm to tears to anger, can occur for no reason.
• Changes in personality. People with dementia often exhibit dramatic personality changes.
• Loss of initiative. People often become very passive, sitting in front of the TV for hours, sleeping more than usual or not wanting to do usual activities.

On the Web

To learn more about dementia, visit the National Institute of Neurological Disorders and Stroke.

SOURCES: HealthDay News ; Robert S. Wilson, Ph.D., professor of neuropsychology, Rush Alzheimer's Disease Center , Chicago ; Alzheimer's Association (www.alz.org)
Author: Anne Thompson
Publication Date: July 31, 2008
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