What Your Nose Knows: How Smell Loss Reveals Parkinson’s Long Before Diagnosis

People living with Parkinson’s often look back and realise their sense of smell began to fade long before diagnosis. Scientists have been interested in this link for years, and new research offers more insight into how early smell loss might help spot Parkinson’s sooner. A team of UK researchers studied over 1,400 people aged between 60 and 80 who did not have Parkinson’s. Everyone completed a short scratch-and-sniff smell test at home, filled out online surveys about sleep and movement, and took a simple keyboard-tapping test to measure hand speed. The study found that smell tends to decline with age and that men usually score lower than women. People who showed signs of a sleep disorder linked to Parkinson’s, where they move or shout during dreams, also had a poorer sense of smell. Those who were slower on the tapping test — showing subtle motor changes — did worse on the smell test too. Interestingly, when people were asked how well they could smell, their answers didn’t match the actual test results. Many didn’t realise how much their sense of smell had faded. This suggests that relying on self-awareness alone isn’t enough to pick up early changes. For people who already have Parkinson’s, these results underline how important smell loss is as part of the disease process. It reinforces the idea that changes in smell can appear many years before diagnosis, alongside early sleep or motor symptoms. While the study focused on people without Parkinson’s, its findings could help researchers design better screening tools and track how the condition develops. A simple smell test done at home could one day help identify those at risk or monitor changes in those already diagnosed. The research doesn’t yet prove that smell loss causes Parkinson’s, and the participants will need to be followed over time to see who develops the condition. But for people living with Parkinson’s, it’s another reminder that the loss of smell isn’t just a small detail — it’s a key part of understanding the disease from its earliest stages.