A strong response to a particular smell can help doctors determine the best treatment for patients who are unconscious, unconscious, or in areas of limited consciousness, known as Disorders of consciousness (DoC).
Diagnosing which disease a patient has can be difficult, however. We’ve used words or pictures to test for DoC, and new research suggests that smell can help, too. With proper control of the research, these conditions can be detected by a well-chosen scent that is placed under the patient’s nose.
“Sweet responses should be considered a sign of knowledge,” write the researchers in their published paper. “The fat response can help in cognitive control and can help in the treatment of diseases.”
A test involving 28 patients in different cognitive categories was conducted by a team at Southern Medical University in China. Various fragrances, including vanillin and decanoic acid, were tested in experiments, while electroencephalograms (EEG) were used to monitor brain activity.
A higher level of consciousness meant a response to smell.
Indeed, after three months, of the 16 patients who had a sense of smell, 10 recovered. This compares to only 2 out of 12 patients from the group that had no response to fat stimulation.
Even in this last group, there were interesting brain patterns, though: in particular, higher theta connections in the brain, which are associated with sleep and relaxation, and lower alpha and beta connections with healthy regulation, brain waves associated with alertness, and effective thinking. .
This was observed with the smell of vanillin, however – and the researchers think that there may be some kind of relationship between the smell of the smell and how people with DoCs will respond.
“Theta connectivity may be a neural correlate of olfactory perception in patients with DoC, which may aid in cognitive assessment and support therapeutic strategies,” the researchers wrote.
Our sense of smell works differently than other senses by not involving the thalamus part of the brain, a type of sensory processing center. Smell has a direct connection with the forebrain, which may be useful in this case, the researchers say.
All of this plays into our understanding of consciousness, how the brain affects smell, and how the two may be connected. However, there is much work to be done on larger populations and more sniffing.
The next step is to find out why the link exists. It’s possible that with less knowledge, we lose our ability to create good smells, researchers suggest – but at the moment, we don’t know.
“Future research should follow cognitive recovery after short-term evaluation,” write the researchers.
“Future research should also include time-related cues or factors that may trigger the smell, which will increase our understanding of how smell is processed.”
Research has been published in Frontiers in Neuroscience.
