A 5-minute odor-identification test may help determine if a patient's mild memory problems indicate early-stage Alzheimer's disease. Researchers believe that the inability to identify smells is one of the first signs of Alzheimer's disease.

In a study of 213 older adults (mean age, 68) with minimal to mild memory impairment, researchers asked each subject to "scratch and sniff" 40 odors and identify each odor via multiple-choice questions. They found that an inability to identify certain odors (see box) predicted the development of Alzheimer's disease. Subjects who never developed Alzheimer's disease typically identified about 35 scents. Those eventually diagnosed with Alzheimer's disease identified only 20 to 30 scents.

Researchers reported their findings at the American College of Neuropsychopharmacology annual meeting in December.

Most patients in early-stage Alzheimer's disease failed to identify these odors:

* clove

* leather

* lemon

* lilac

* menthol

* natural gas additive

* pineapple

* smoke

* soap

* strawberry.