Seems the left nostril begins to lose its ability to detect an odor (doesn't have to be peanut butter) in the early stages of Alzheimer's disease:
"One of the first places in the brain to degenerate in people with Alzheimer’s disease is the front part of the temporal lobe that evolved from the smell system, and this portion of the brain is involved in forming new memories."How they conducted the test:
"In the study, patients sat down with a clinician, 14 grams of peanut butter — which equals about one tablespoon — and a metric ruler. The patient closed his or her eyes and mouth and blocked one nostril. The clinician opened the peanut butter container and held the ruler next to the open nostril while the patient breathed normally. The clinician then moved the peanut butter up the ruler one centimeter at a time during the patient’s exhale until the person could detect an odor. The distance was recorded and the procedure repeated on the other nostril after a 90-second delay.Handedness mattered:
The scientists found that patients in the early stages of Alzheimer’s disease had a dramatic difference in detecting odor between the left and right nostril — the left nostril was impaired and did not detect the smell until it was an average of 10 centimeters closer to the nose than the right nostril."
"This was not the case in patients with other kinds of dementia; instead, these patients had either no differences in odor detection between nostrils or the right nostril was worse at detecting odor than the left one."Everyone I know will be smelling peanut butter.