‘Scratch and Sniff’ Test Sheds Light on Depression

Long Beach, Calif. (April 21, 2023)—A five-minute test commonly used to evaluate olfactory function (sense of smell) could also help doctors screen for depression, according to new research out of King George’s Medical University, India. The research will be presented this week at the American Physiology Summit, the flagship annual meeting of the American Physiological Society (APS), in Long Beach, California.

“BSIT-12 as a validated test for olfaction may be useful in diagnosing depression severity and prognosis with treatment.” —Manish Bajpai, MD

According to the World Health Organization, depression is a leading cause of disability, affecting 1 in 20 adults around the globe. There is a known correlation between loss of smell and depression, often assessed by comparing depression diagnosis with the results of the University of Pennsylvania Smell Identification Test (UPSIT).

The UPSIT is a commercially available, standardized and trusted screening tool of 40 scratch-and-sniff samples that require the user to identify scents using corresponding multiple-choice questions. The Brief Smell Identification Test (B-SIT) is a rapid version of the UPSIT that uses 12 smells instead of 40. Identifying eight or fewer smells on the B-SIT is considered abnormal.

The current study screened 35 people diagnosed with depression and 32 age- and sex-matched healthy controls. All the members of the depression group identified fewer smells than the control group. Twenty-seven participants in the depression group scored below the cutoff score of eight. Participants with recurrent depressive episodes had a mean BSIT score of 5.20.

“To our surprise, we found that the degree of olfactory dysfunction was directly proportional to the severity of depression,” said lead study author Manish Bajpai, MD.

“The easy and rapidity of the B-SIT could make a useful addition to clinical screening,” researchers wrote.

NOTE TO JOURNALISTS: The American Physiology Summit will be held April 20–23, 2023, in Long Beach, California. To schedule an interview with the researchers, conference organizers or presenters, contact APS Media Relations or call 301.634.7314. Find more highlights from the meeting in our Summit Newsroom.

Physiology is a broad area of scientific inquiry that focuses on how molecules, cells, tissues and organs function in health and disease. The American Physiological Society connects a global, multidisciplinary community of more than 10,000 biomedical scientists and educators as part of its mission to advance scientific discovery, understand life and improve health. The Society drives collaboration and spotlights scientific discoveries through its 16 scholarly journals and programming that support researchers and educators in their work.