Poor Sense of Smell May Signal Alzheimer’s Risk

A person’s sense of smell may help predict their risk for Alzheimer’s disease, a new study suggests.

The researchers included 183 older people, and 10 had possible or probable Alzheimer’s disease, the researchers said.

Study volunteers were tested on their ability to recognize, remember and distinguish between odors. These odors included menthol, clove, leather, strawberry, lilac, pineapple, smoke, soap, grape or lemon. The study participants were then asked to complete another test of odors. The second test included 10 new odors in addition to those from the original test. These tests were developed at Massachusetts General Hospital in Boston.

The participants also underwent genetic, imaging and memory tests. Those with a reduced sense of smell seemed to be at increased risk of Alzheimer’s, the researchers said.

“There is increasing evidence that the neurodegeneration behind Alzheimer’s disease starts at least 10 years before the onset of memory symptoms,” principal investigator Dr. Mark Albers, from the department of neurology at Massachusetts General, said in a hospital news release.

“The development of a digitally enabled, affordable, accessible and noninvasive means to identify healthy individuals who are at risk is a critical step to developing therapies that slow down or halt Alzheimer’s disease progression,” he added.

Sense of Smell May Predict Longevity

A defective sense of smell appears to be a good predictor of longevity, a new study has found.

Researchers tested a nationally representative sample of 3,005 men and women age 57 to 85 on their ability to identify five smells: rose, leather, orange, fish and peppermint. The study appears online in PLOS One.

They controlled for many factors – age, sex, socioeconomic status, smoking, alcohol intake, education, body mass index, race, hypertension, diabetes, heart attack, emphysema, stroke and diet. But still, people who could not detect the odors were more than three times as likely to die within five years as those who could. The lower their scores on the odor test, the more likely they were to die. Only severe liver damage was a better predictor of death.

The researchers believe that the decline in the ability to smell is an indicator of some other age-related degeneration, and is not itself a cause of death.

The lead author, Dr. Jayant M. Pinto, an associate professor of surgery at the University of Chicago, said that loss of smell should not be ignored. “There are treatable causes of olfactory loss,” he said, “so if people have problems, they should get evaluated. This is a gross indication of your health, so if you’re having some trouble, you should see a doctor.”