A critical sense linked to a whole host of diseases has long lurked right under—or rather within—our noses.
While doctors often check patients’ hearing and eyesight, it’s far less common to test people’s sense of smell. But one’s “smell health” is potentially linked to more than 139 conditions that manifest throughout the body, including Alzheimer's disease, congestive heart failure, and Parkinson's disease, according to a review recently published in Clinical Otolaryngology.
The COVID-19 pandemic has drawn more attention to olfactory dysfunction, which refers to smell loss or an altered sense of smell, but the authors noted that cases are likely underdiagnosed. “The sense of smell has lagged behind the senses of sight and hearing in terms of its perceived importance and remains the Cinderella sense,” they wrote.
The authors cite the fact that olfactory dysfunction currently affects around 22 percent of people globally, and it’s particularly prevalent among men and people over the age of 60. Most often associated with aging, olfactory dysfunction can also be caused by upper respiratory infections like COVID-19, head trauma, or chronic sinus inflammation. Some sufferers report it as a side effect of certain medications, like some drugs that treat high cholesterol.
Read more: “The Doctor Will Sniff You Now”
Regular screening for olfactory dysfunction is crucial because it can lead to early detection of certain diseases. For example, partial or full loss of smell can occur more than four years before the motor symptoms of Parkinson’s disease, the paper points out. The nose may signal neurodegenerative conditions years before other signs emerge because damage may commence in parts of the brain associated with smell before such deterioration causes more systemic problems.
Olfactory dysfunction might also be linked to a 10-year risk for stroke and long-term risk for congestive heart failure, a finding in older adults who reported they were otherwise in good health. More broadly, smell health seems to strongly predict mortality in older adults.
A good sense of smell is also essential for healthy eating: People with smell and taste disorders tend to have diets higher in calories, fat, and added sugar, which can lead to nutritional deficiencies and obesity.
Ultimately, scents are crucial for our overall well-being, the paper emphasized. Individuals with olfactory dysfunction experience high rates of eating disorders, depression, and social isolation. That’s because smell is inextricably linked to our enjoyment of food, social communication, and avoiding harms like spoiled food and smoke.
The authors urged that smell “should be promoted as an essential pillar of health.” They recommend educating healthcare providers around the globe on olfactory dysfunction, ramping up related research to identify treatments, and increasing access to smell testing.
After all, the nose knows a lot more about our health than you might think. 
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Lead image: Rijksmuseum / Wikimedia Commons
