Our sense of smell can sometimes come and go, especially when a clogged nose from a cold or flu prevents air from moving through. But new research is showing that sustained changes in a person’s sense of smell could be an early indicator of how likely they are to die.
While the connection might seem like a strange one, the link is based on good data from prior studies. Loss of smell occurs in many diseases towards the end of life, including Alzheimer’s and Parkinson’s. Dementia, frailty, and even mild cognitive impairment can also be accompanied by loss of smell. Our sense of smell relies heavily on a healthy brain because both the receptors in the nose and the smell neurons in the brain turn over often and frequently need to be regenerated. The idea is that as a person’s health starts to decline, their brain’s ability to maintain itself also starts to deteriorate, leading first to a loss of smell before other functions slowly stop working.
To test that hypothesis, the researchers recruited 3,005 individuals in the community between the ages of 57 and 85 and tested their sense of smell with a variety of scented felt-tip pens. Five scents (rose, leather, orange, fish and peppermint) were presented at once and the participants had to identify at least four of the scents that were present to be normal. Five years later, the researchers followed up with each participant to see how many were still alive and what their overall health was.
The results were striking. Those who had completely lost their sense of smell were more than three times as likely to have died after five years than those who made no mistakes. But it wasn’t just those who couldn’t smell. With each additional mistake, the risk for death increased, with those making three mistakes about 50% more likely to have died and those making four mistakes about two and a half times more likely to have died.
The authors say they think our sense of smell is the canary in the coal mine when it comes to brain health. As such, testing smell could become a part of regular exams as people age, especially given how simple the test is. It would give doctors an early warning sign that someone’s health is deteriorating, allowing them to take steps to try and boost their health by addressing possible causes of decline.
It also provides individuals with an early warning sign that something might be wrong with their health. It’s important to note that there can be other, reversible causes of loss of smell that may have nothing to do with how likely you are to die in the future. If you experience any change in your smell or find yourself unable to sense smells that you could previously, you should see a doctor and get it checked out.