Scientists have discovered that the nose could hold the key to diagnosing a variety of health conditions. A recent study suggests that problems with your sense of smell could be more than just an inconvenience – they might be an early sign of a wide range of medical conditions.
The research, published in Frontiers in Molecular Neuroscience, reveals that impaired smell is associated with at least 139 different medical conditions, including Alzheimer’s disease and cardiovascular problems. The findings suggest that your sense of smell could be one of the first systems to warn you when something’s wrong in your body.
In many cases, the loss of smell actually precedes the development of other symptoms, sometimes by years. The team from the University of California found that people who later develop Parkinson’s disease often report a reduced sense of smell long before they exhibit any movement-related symptoms.
Similarly, individuals who eventually develop Alzheimer’s disease frequently cite issues with their sense of smell as one of their earliest symptoms, even before they notice any memory problems. They also highlighted an apparent link between loss of smell and inflammation throughout the body.
Researchers have made a startling revelation that all 139 conditions known for causing loss of smell also share a connection with inflammation. This ground-breaking study categorises these health issues into three main types: neurological, which affects the brain and nervous system; somatic, which influences the body; and congenital/hereditary, which individuals inherit or are present at birth, exemplifying the broad scale of this tie-up.
Conditions range from mental health concerns such as depression and anxiety to physical ailments like diabetes and heart disease. On a positive note, the investigation disclosed that “olfactory enrichment” – basically, exercises revolving around smelling various odours – might act as a protective measure against some of these effects.
In a hopeful stride forward, fresh research showed that dementia patients who sniffed 40 different scents twice daily over two weeks displayed boosted memory, concentration, and language abilities. Professor Michael Leon, leading the charge on this innovative approach, shared: “The data are particularly interesting because we had previously found that olfactory enrichment can improve the memory of older adults by 226 percent,” adding that “We now know that pleasant scents can decrease inflammation, potentially pointing to the mechanism by which such scents can improve brain health.”
If you’re experiencing a diminished sense of smell, it could be wise to mention it to your GP.
The medical conditions linked to both smell loss and inflammation are listed below.
Neurological conditions
- Alzheimer’s disease
- Parkinson’s disease
- Multiple sclerosis
- Depression (both unipolar and bipolar)
- Anxiety
- Autism
- Epilepsy
- Chronic fatigue syndrome
- Memory loss with ageing
- Long Covid
- Migraine headaches
- Sleep disorders (including narcolepsy and sleep apnea)
- PTSD (Post-traumatic stress disorder)
- Schizophrenia
- Traumatic brain injury
- Stroke
- Cluster headaches
- Fibromyalgia
- Various types of dementia
- And many others related to brain and nerve function.
Body-wide conditions
- COVID-19
- Cardiovascular disease
- Diabetes
- Obesity
- Cancer (head and neck)
- HIV/AIDS
- Allergies
- Asthma
- Arthritis
- Celiac disease
- Crohn’s disease
- Cirrhosis
- Heart failure
- Kidney disease
- Malnutrition
- High blood pressure
- Thyroid problems
- Vitamin B12 deficiency
- Vitamin D deficiency
- And dozens more affecting various body systems.
Inherited/genetic conditions
- Down syndrome
- Fragile X syndrome
- Cystic fibrosis
- Wilson’s disease
- Various rare genetic disorders affecting metabolism and development.
Additional notes:
- Some conditions have stronger evidence than others
- COVID-19, Alzheimer’s, Parkinson’s, depression, and rhinitis (nasal inflammation) have particularly extensive research backing the connection
- Some connections are based on single studies and need more research
- The complete list includes many more specific conditions within each category.