Losing your sense of smell may seem like a minor inconvenience—making food taste bland or reducing your enjoyment of fragrances—but emerging research suggests it could signal far more serious health concerns.
According to a review published in Frontiers in Molecular Neuroscience, olfactory dysfunction (loss of smell) is linked to at least 139 different medical conditions. This revelation underscores the importance of our sense of smell, not only for daily experiences but also for maintaining overall health.
Conditions Associated With Loss of Smell
The study identified numerous diseases and disorders that correlate with olfactory dysfunction. These range from neurological disorders to mental health conditions, as well as metabolic and inflammatory diseases. Some of the most notable include:
- Neurodegenerative diseases: Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, multiple sclerosis, and frontotemporal dementia
- Mental health disorders: Anxiety disorder, bipolar disorder, depression, schizophrenia, obsessive-compulsive disorder (OCD), and post-traumatic stress disorder (PTSD)
- Chronic conditions and systemic diseases: Fibromyalgia, menopause-related issues, long COVID, and heavy metal exposure
- Cancer: Glioblastoma, an aggressive type of brain cancer
Given the wide-ranging impact of olfactory dysfunction, researchers believe that losing one’s sense of smell could serve as an early warning sign of underlying health issues.
What Causes Loss of Smell?
Many factors can contribute to a diminished sense of smell, including sinus infections, exposure to air pollution, smoking, and certain medications. However, researchers are now finding strong connections between olfactory dysfunction and brain health.
According to Michael Leon, PhD, lead author of the study and professor emeritus of neurobiology and behavior at the University of California Irvine, inflammation may play a key role.
He said, “The loss of the sense of smell is accompanied by an increased level of chronic inflammation, which has been shown to increase the risk of many medical conditions.”
Inflammation affects the brain in different ways, but one consistent finding is that olfactory dysfunction often precedes the onset of neurological conditions. This means that losing your sense of smell could be an early symptom of diseases like Alzheimer’s, Parkinson’s, and even certain types of cancer.
A “Canary in the Coal Mine” for Brain Health
Medical experts emphasize that changes in olfactory function should not be ignored.
According to Zara M. Patel, MD, professor of otolaryngology at Stanford University School of Medicine, olfactory dysfunction serves as a crucial indicator, “The sense of smell is like the ‘canary in the coal mine,’ with any deficit or disorder signaling that something in your brain has gone awry.”
In the past, doctors often viewed loss of smell as an unfortunate but harmless symptom of aging or sinus issues. However, the growing body of research suggests that it may be an early marker of serious brain deterioration.
The Link Between Smell and Mood Disorders
One particularly intriguing aspect of olfactory dysfunction is its strong connection to mental health conditions such as depression, anxiety, and bipolar disorder.
Jayant Pinto, MD, a surgery professor and vice dean of faculty affairs at the University of Chicago, explains how the olfactory system is deeply intertwined with emotional regulation:
“This would be one reason decreased smell function is associated with mental health problems like anxiety and depression.”
The olfactory bulb, responsible for processing smells, is directly linked to brain regions that regulate emotions and memory. When this system is disrupted, it can lead to or exacerbate mood disorders.
This connection is particularly concerning given the rise of long COVID, where many individuals report a lingering loss of smell and increased rates of depression and anxiety. The implications of this research suggest that addressing olfactory dysfunction could also support mental health and cognitive function.
Can Loss of Smell Be Treated?
Given the serious consequences associated with olfactory dysfunction, researchers are actively investigating ways to restore or improve the sense of smell. One promising approach is olfactory enrichment therapy, a method that involves exposing individuals to various scents to stimulate the olfactory system.
According to Dr. Leon, this method holds potential beyond just restoring smell, “Olfactory enrichment not only improves the sense of smell, but by stimulating that sense, you activate the memory and emotional areas of the brain, keeping them healthy.”
How Olfactory Enrichment Works
Olfactory enrichment typically involves:
- Aromatherapy: Using essential oils such as eucalyptus, rose, lemon, and clove to stimulate the olfactory nerves
- Scent training exercises: Smelling and identifying different scents to improve neural connections
- Exposure to diverse odors: Encouraging the brain to rewire itself and regain sensitivity to smells
Early studies suggest that olfactory enrichment could help slow cognitive decline and even reduce inflammation in the brain, making it a potential therapeutic tool for neurological and mental health conditions.
The Bigger Picture: Why This Research Matters
The findings from this research review challenge the common perception that losing your sense of smell is merely a minor inconvenience. Instead, it may be one of the earliest warning signs of serious health conditions—from Alzheimer’s disease to schizophrenia and even brain cancer.
Given its connection to inflammation, brain function, and mental health, olfactory dysfunction should be taken seriously as a biomarker for overall well-being.
When to Seek Medical Advice
If you notice a persistent loss of smell, experts recommend seeking medical attention—especially if there’s no obvious cause, such as a cold or allergies. Given its links to neurodegenerative diseases and mood disorders, early intervention could make a significant difference in preventing or delaying serious health issues.
A Path Forward: The Future of Olfactory Research
With growing awareness of olfactory dysfunction’s role in early disease detection, scientists are now exploring innovative ways to use smell testing as a diagnostic tool. In the future, routine olfactory screenings may become as common as vision and hearing tests, providing doctors with an early window into a patient’s brain health.
By recognizing the importance of our sense of smell, medical science is opening new doors to understanding, preventing, and treating a wide range of diseases.