Sense Of Smell May Predict When You’ll Die


Researchers from Salk Institute for Biological Studies found a correlation between declining ability to smell and lifespan in worms.

“We’re not saying that your ability to smell is going to make you live longer,” Sreekanth Chalasani, an assistant professor in Salk’s Molecular Neurobiology Laboratory, said in a statement. “But this odor behavior is likely indicative of some kind of underlying physiology.”

For the study, researchers conducted an experiment with nematodes (Caenorhabditis elegans) that examined how they process information about the environment and how circuits in the brain change as an animal ages.  They worms have 12 pairs of specialized neurons in its brain that detect stimuli in the environment.

Researchers measured the responses of all 24 neurons as C. elegans was exposed to benzaldehyde, a chemical that gives off a pleasant, almond-like smell. Scientists had previously identified individual pairs of these neurons as required for the animals to respond to attractive odors.

Researchers also divided the cells into primary and secondary neurons.

“Primary neurons showed activity in response to the benzaldehyde,  while secondary neurons responded to signals sent by the primary neurons. By having a neural circuit structured like this, the team hypothesizes, the worm can get better information on the strength or concentration of a smell,” researchers said in the study.

The researchers next measured how the circuit composed of primary and secondary neurons changed as C. elegans gets older. While the primary neurons don’t show a decline in activity, they found, secondary neurons become less active with age.

Chalasani said this findings suggests that communication between neurons could be degraded as animals age.

“There are a lot of questions that remain about what exactly is changing as an animal ages,” Sarah Leinwand, first author of the study, said in a statement. “We want to keep looking at what is changing to cause some animals to have better functioning nervous systems and to live longer.”



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