Even with more recent technologies, such as brain imaging, the rate of misdiagnosis in DOC [disorders of consciousness] patients could be as high as 40%.
Besides the fact that we do not even have a full understanding of what consciousness is, one of the challenges in diagnosing DOCs is that it’s difficult to distinguish between people in persistent unresponsive states, and minimally responsive ones (who have inconsistent but present responses).
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New research by Anat Arzi and colleagues at the Weizmann Institute of Science [in Israel] … presents a new technique that might allow us to use the sense of smell as an indicator of consciousness. … The scientists took advantage of something called sniff response — basically the way our brain automatically sniffs in response to a certain stimulus. For example, if you open your garbage and there is something spoiled in it, you will almost reflexively reduce the amount of air you inhale. On the other hand, when walking into your favorite coffee shop, you might inhale more than the normal amount of air to take everything in.
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About 90 percent of the patients with a positive sniff-response survived the following years, while for the patients without any response that number was closer to 35 percent. Overall, this suggests strong correlations between how DOC patients respond to different smell stimuli, and their diagnoses and outcomes.
