Smell Test

Olfactory bulb (Yale School of Medicine image)

One symptom of Parkinson's Disease is the loss of the sense of smell, and Yale researchers may have discovered the connection.

Using buried food tests, the researchers found that the mice with later stage symptoms of Parkinson’s disease exhibited olfactory impairment. They found that those mice with olfactory deficits exhibited severe pathology in projection neurons of the olfactory pathway.

They also found these mice showed reduced neurogenesis in the olfactory bulb. In contrast, studies have shown that healthy aging brains continue to form new neurons in the olfactory bulb throughout life.

The Parkinson's finding on the degradation of olfactory cells may also provide a clue about why some COVID patients experience "brain fog" and the loss of their sense of smell.

A Dog Knows

(Image from pet poo skiddoo)

Acting calm before a threatening dog won't fool it if you're fearful inside. A dog knows: [bold added]

Dogs are champion sniffers, equipped with 100 to 300 million olfactory receptors in their noses—compared with a mere 6 million in our own—and an olfactory cortex 40 times as large as ours. They can be trained to detect disease in human beings, including cancer cells, a latent epileptic seizure, or a Covid infection, just by sniffing—no blood samples, biopsies, MRIs, antigen or PCR tests required.

In a study published in September in the journal PLoS One, Ms. [Clara] Wilson and colleagues tested whether dogs can read and respond to our emotional states, without the benefit of facial expression, tone of voice, or social context...The results offered overwhelming confirmation that dogs can smell psychological states as well as physical ones. On average, the four dogs picked out the stress sample 94% of the time, with individual dogs ranging between 90% and 97% accuracy.

A barking dog can smell your fear. Acting lessons won't help you, and neither, probably, will psychological self-trickery (e.g., meditation).

As for me, I plan to have liquid courage close at hand.