Practice Smelling
What do we know?
It’s been known for a while that loss of smell is associated with age-related cognitive decline, Dementia and Parkinson’s Disease (plus a wide range of other neurological conditions caused by inflammation)[i].
We also know that a waft of a particular scent can bring a strong reminder of particular events, even from our childhood. The smell (olfactory) nerve is linked straight to the olfactory bulb, the part of the brain immediately above the nose which has strong connections to memory and emotion centres in the brain[ii].
[i] Inflammation and olfactory loss are associated with at least 139 medical conditions. M Leon at al. Frontiers of Molecular Neuroscience. Oct 2024.
[ii] Why honing your sense of smell could keep you sharp as you age. D Robson. New Scientist; May 2025
So what’s new
New genetic studies show that gene variants (APOe4) that are associated with Alzheimer’s, are also linked to smell loss well before memory loss is noted[i].
Damage to the olfactory nerve causes shrinkage in connected parts of the brain.
Some researchers are now suggesting that the loss of smell may be contributing to the cognitive decline. Damage to the olfactory nerve causes shrinkage in connected parts of the brain – parts linked to cognition (frontal cortex) and emotion (hippocampus). Some putrid smells increase inflammatory response, whereas others reduce inflammatory markers. It may be that a healthy nose helps keep the immune system in balance[ii]. The best news is that training the sense of smell can slow or reverse some signs of cognitive decline, with growth of areas in the brain such as the hippocampus[i].
[i] Does Olfactory Training Improve Brain Function and Cognition? A systematic review. DE Vance. Neuropsychologcal Review. March 2024
[i] Association of APOE4 Status with long-term declined in Smell and Cognition. M GoodSmith et al. Neurology Sept 2023.
[ii] Disgusting Odors trigger the oral immune system. M Olsson et al. Evolotion, Medicine and Public Health, Dec 2022.
What should we do?
Sense of smell can be trained and reinvigorated. This has been a treatment for people who suffered from loss of smell after Covid infections, but is now being used to improve memory.
It is possible to buy “smell training kits” - clove, lemon, eucalyptus and rose: smell each vial for 10 to 20 seconds each and do this twice a day. These scents were used in the studies above and seem to lessen inflammation along the nerve and into the brain, and stimulate mood and cognition.
A wider range of scents can be used as your nose is retrained. Enjoy a walk after spring shower, smell the flowers and enjoy the aroma from cooking and wine!
It is possible to train your sense of smell to stimulate cognition and improve mood.
