Getting Old Sux

[Churak]

Alzheimer's linked to poor sense of smell

Study finds those who do poorly on odour tests more likely to show mental decline over time

Jul 03, 2007 04:30 AM
Associated Press

CHICAGO–Difficulty identifying common smells such as lemon, banana and cinnamon may be the first sign of Alzheimer's disease, according to a study that could lead to scratch-and-sniff tests to determine a person's risk for the progressive brain disorder.

Such tests could be important if scientists find ways to slow or stop Alzheimer's and the memory loss associated with it. For now, there's no cure for the more than 5 million Americans and estimated 300,000 Canadians over 65 with the disease.

Researchers have long known that microscopic lesions considered the hallmarks of Alzheimer's first appear in a brain region important to the sense of smell. "Strictly on the basis of anatomy, yeah, this makes sense," said Robert Franks, an expert on odour perception and the brain at the University of Cincinnati. Franks was not involved in the study, appearing in yesterday's Archives of General Psychiatry.

Other studies have linked loss of smell to Alzheimer's, Franks said, but this is the first one to measure healthy people's olfactory powers and follow them for five years, testing for signs of mental decline.

In the study, 600 people between the ages of 54 and 100 were asked to identify a dozen familiar smells: onion, lemon, cinnamon, black pepper, chocolate, rose, banana, pineapple, soap, paint thinner, gasoline and smoke. For each mystery scent, they were given a choice of four answers. A quarter of the people correctly identified all the odours or missed only one. Half of them knew at least nine of the 12. The lowest-scoring quarter correctly identified eight or fewer of the odours.

The subjects took 21 cognitive tests annually over the next five years. Those who made at least four errors on the odour test were 50 per cent more likely to develop memory problems than people who made no more than one error. Difficulty identifying odours also was associated with a higher risk of progressing from mild cognitive impairment to Alzheimer's.