Ever wonder what causes "old person smell" -- and if such a thing is just your imagination or actually exists? Yup, the very old do smell different from you and me, according to research by the Monell Chemical Senses Center and elsewhere. The Japanese call this odor, kareishuu. Scientific American, reporting on the new research, dubs it "eau de elderly."
Blame the process of natural decay. Sweat glands secrete an odorless, salty liquid through life, but as bacteria break down the chemicals in the liquid into smaller, more odorous molecules, a body odor can be detected.
Animal studies have shown that many species can differentiate old from young by scent, possibly as a way to identify the sick and dying. In humans, researchers speculate we may be smelling underlying cell decay, a long-term process, rather than actual imminent demise.
The Monell scientist divided volunteers into three age groups: 20 to 30, 45 to 55, and 75 to 95. For five nights, they wore the same shirts, into the armpits of which absorbent nursing pads had been sewn. Another group then gave the pads a sniff test while blindfolded to rate the odors' intensity and appeal, and to categorize them as "young," "middle-age" or "old-age."
The older-person's smell was the easiest to identify. But it was also rated as less offensive than any other. The study is reported in the May 30 PLoS ONE.
"I think it's true that old people smell a certain way," researcher Johan Lundström says, "but the idea that the smell is negative may largely be social stigma." Other work has found that the compound contributing to a distinctive elderly adult odor has also been linked to the scent of cucumbers and aged beer.
And if you're not crazy about aged beer, luckily there are caregiving secrets to [making your house smell better](http://www.caring.com/articles/home-care-make-the-house-smell-better
Image by Flickr user Josh_Lowe, used under a Creative Commons license.