Researchers have developed a novel smell test that is easy to use in patients with Parkinson's and Alzheimer's, and could also be helpful in diagnosing COVID-19.

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The smell testing kit, developed by Queen Mary University of London researchers, includes capsules of aromatic oils placed between two strips of single-sided tape. To take the smell test, the capsules are simply crushed between the fingers and the tape strip peeled to release the aroma contained within the capsules. Based on a person's ability to recognise these smells, a score would be generated that can be sent to doctors if they are experiencing a loss of smell.

"Our capsule-based smell test can assist in the rapid diagnostic of various diseases linked to the loss of smell. These include chronic neurological conditions such as Parkinson's and Alzheimer's disease, as well as COVID-19, which is known to affect the sense of smell", said lead researcher Ahmed Ismail from Queen Mary's School of Engineering and Materials Science. "Being non-invasive and less stressful, the capsule-based smell test has benefits over the nose swab in diagnosing COVID-19. This is an advantage for testing children in particular, as they are typically horrified if they need to do a nose swab, and the test can be done in the comfort of their own home", Ismail added.

The study, published in the journal Royal Society Interface, showed that, in a small group of eight patients with Parkinson's disease, the smells from the tests were detectable. The participants also cited the relative ease process of rupturing the capsules, particularly for those with tremors, compared to the standard scratch and sniff smell test available on the market. Moreover, in the capsule-based smell test, "the amount of odour released is controlled by the amount of oil precisely encapsulated. The mass-production of our new test would also be cheaper than a scratch and sniff test", Ismail noted.